Recently in Planetary and space science Category

BBC: Due to financial woes, NASA may be forced to withdraw from its partnership with the European Space Agency (ESA) on the dual ExoMars robotic space missions. NASA expects to know more after 13 February, when President Obama announces his 2013 budget. The US agreed to provide equipment and launch rockets for an orbiter and a rover to go up in 2016 and 2018, respectively. Because ESA has already invested heavily in the ExoMars project, it has started looking for other partners, foremost of which is the Russian space agency Roscosmos. This is not the first time the US has reneged on a project with Europe, so the decision may have "grave implications for transatlantic relations," writes Jonathan Amos for the BBC.

Nature: Small fission reactors may be used to power future NASA manned space missions. With twice the efficiency of chemical rockets, the reactors could send astronauts farther into space and at a much higher rate of speed, writes Eric Hand for Nature. Although researchers have been exploring the technology for years, funding has been problematic—until now. In a National Research Council report released 1 February, nuclear power and propulsion were ranked high on a list of the most important areas of technology development. And public opinion regarding nuclear power may be changing. Whereas the 1997 launch of Cassini–Huygens, with a radioisotope generator, was protested by antinuclear activists, the November 2011 launch of the Mars Science Laboratory, which also has a radioisotope generator, did not generate the same level of public concern.

BBC: Yesterday an international team of astronomers and engineers succeeded in linking all four of the large telescopes that make up the European Southern Observatory's Very Large Telescope, located on Cerro Paranal in Chile's Atacama Desert. Each of the four has been up and running since at least 2000. However, when linked together via interferometry, they form the biggest ground-based optical telescope on Earth, which offers very high spatial resolution and zooming capabilities. "From now on we'll be able to observe things we were not able to observe before," said Frederic Gonte, head of instrumentation.

Telegraph: Researchers at Imperial College London have determined that life could not exist on the surface of Mars because of a super drought that lasted hundreds of millions of years, writes Nick Collins for the Telegraph. Experts spent three years studying individual soil particles collected in 2008 by NASA's Phoenix spacecraft. Despite a warmer and wetter period in Mars's distant past, the 5000 years or so that it lasted was simply too brief for life to have established itself on the surface. "Future NASA and ESA [European Space Agency] missions that are planned for Mars will have to dig deeper to search for evidence of life, which may still be taking refuge underground," said Tom Pike, lead author of a paper published in Geophysical Research Letters.

Florida Today: NASA isn't adequately prepared to evacuate the International Space Station (ISS) in an emergency, says a new report from the Aerospace Safety Advisory Panel (ASAP). The report recommends that the agency improve its emergency drills and consider alternative "lifeboat" options for ISS. There is a greater than 30% chance that a crew might have to abandon ISS between now and 2020, the planned end of ISS operations, as a result of the failure of critical systems or a deadly space debris strike, says ASAP. The panel also found NASA lacks an adequate plan to safely send the station to a remote spot in the Pacific Ocean at the end of its useful life. ASAP was created by Congress after the loss of three astronauts in the 1967 Apollo 1 launch pad fire. The group is made up of aerospace safety experts and reports to the vice president, the Speaker of the House, and the NASA administrator each year.

Financial Times: Madhavan Nair, former head of the Indian Space Research Organisation (ISRO), has been banned from government employment because of allegations that he was involved in the underpriced leasing of space spectrum to the private sector, write James Fontanella-Khan and James Lamont for the Financial Times. Nair, who supervised 25 space missions during his tenure from 2003 to 2009, earned international recognition for his efforts to put India's space program on a par with those of China and Japan. Since 2009, when he retired from ISRO, he has served as president of the Paris-based International Academy of Astronautics. Regarding the allegations, Nair claimed he was not given any opportunity to defend himself, and one space expert suggested that they were politically motivated. No criminal charges have been filed.

Washington Post: A solar storm on Sunday was expected to send streams of radiation toward Earth today, which could affect satellite communications and GPS signals, as well as the electrical grid. The storm, the biggest since 2003, began with a burst of x rays shooting out of a sunspot; that event was followed by a coronal mass ejection that pushed a cloud of plasma and charged particles toward Earth. Although space weather experts were not anticipating any catastrophic effects, they alerted several groups, including satellite operators, the Electric Power Research Institute, and the White House's Office of Science and Technology Policy. In addition to any inconveniences the storm may cause, North America could see some vivid auroras at lower latitudes.

Telegraph: Two British amateur astronomers, Chris Holmes and Lee Threapleton, may have discovered a new planet. Inspired by Brian Cox’s Stargazing Live TV series, they studied time-lapse images of stars posted online at Planethunters.org. The site, which is part of the Zooniverse citizen science project, encourages users to identify extrasolar planets from data recorded by the Kepler space telescope. Holmes and Threapleton looked for anomalies in light patterns and found that a planet appeared to be orbiting a sun called SPH10066540, which lies 600–3000 light-years away. Thought to be gaseous and about the size of Neptune, the new planet will be named Threapleton Holmes B, provided the discovery is authenticated.

National Geographic: Phobos-Grunt, the failed Russian Mars probe that has been stuck in low Earth orbit for more than two months, is expected to re-enter the atmosphere around Sunday. The Russian space agency Roscosmos expects about 20–30 satellite fragments to reach the ground; the rest should burn up when the craft re-enters the atmosphere. The craft is already visible as a rapidly moving starlike object in the night sky; as it descends into the denser layers of the atmosphere, it will form a long plasma tail and resemble a brightly glowing comet. When it breaks up, it will leave a debris trail that should be visible for up to two minutes. The pieces that fall to Earth should pose very little risk to people, and Roscosmos expects the 11 tons of fuel carried by the satellite to be consumed during reentry.

New York Times: The Russian spacecraft Phobos-Grunt, launched this past November, wound up stranded in low-Earth orbit shortly after launch instead of heading for Mars's larger moon Phobos as planned. It's expected to re-enter Earth's atmosphere this Saturday. In an interview with the newspaper Izvestia, Vladimir Popovkin, chief of the Russian Federal Space Agency (Roscosmos), said that the craft may have failed as a result of sabotage, via an antisatellite weapon or interference with the craft while it was on the ground. He did not state who he thought the saboteur might be; his remarks have been taken as most probably referring to the US. Roscosmos spokesman Alexei Kuznetsov has refused to elaborate on Popovkin's comments, which contrasted sharply with the cooperative spirit of recent Russian civilian space endeavors carried out in partnership with NASA, the European Space Agency, and other foreign partners.

Science: Representing five years of work in imaging 10 million galaxies at distances of about 6 billion light-years, the new dark-matter map is 100 times larger than the largest one to date, writes Govert Schilling for Science. Although dark matter, which represents 98% of the mass of the universe, cannot be seen directly, it exerts a gravitational pull on normal matter, including light. By measuring that pull on starlight, astronomers were able to map its distribution. The new map shows that dark matter is concentrated in huge clumps and filaments, with large empty regions in between. Astrophysicist Ludovic Van Waerbeke of the University of British Columbia in Vancouver, Canada, and colleagues presented their results at the 219th meeting of the American Astronomical Society. Scientists hope that by plotting the distribution of dark matter throughout space, they will come closer to understanding what it is.

Daily Mail: A plutonium-powered pilotless aircraft, Aviatr, has been designed to fly around Saturn’s largest moon, Titan. It would take three-dimensional photos of the moon’s surface, which is hidden from Earth’s view by Titan’s cloudy atmosphere, and even try to land on it. Although a rival balloon project has also been proposed, Aviatr’s designers maintain that the plane would do the best job because its altitude could be controlled more precisely and its plutonium-powered generator could keep Aviatr on the day side of Titan to make the most of its photographing time. With a projected cost of $715 million, Aviatr did not make NASA’s last round of funding. However, Jason Barnes, a scientist at the University of Idaho and one of the craft’s designers, remains optimistic that it will make the next round.

New York Times: The Chinese government has announced a five-year space-exploration plan that calls for launching a space laboratory and collecting samples from the Moon, all by 2016, along with a powerful manned spaceship and space freighters. The plan includes a major expansion of the Beidou Navigation Satellite System, which on Tuesday began providing navigation, positioning, and timing data on China and surrounding areas. China intends to expand Beidou from its current 10 satellites to 35 satellites in orbit by 2020.

NPR: Traveling at 636 miles per minute, Voyager 1 is headed toward interstellar space . Right now, the craft is in the outermost layer of the heliosphere, the bubble of charged particles the Sun forms around itself. The solar wind in that area is nil, but the 100-fold greater intensity of high-energy electrons in elsewhere in the galaxy indicates an approaching boundary. Voyager 1 is expected to cross that boundary sometime in the next three years.

SF Gate: A pair of spacecraft known as Grail-A and Grail-B are set to enter orbit around the Moon over the New Year’s weekend. They launched from the Florida coast in September and are independently traveling to their destination. Over the next two months they will fly in formation around the Moon until they’re approximately 56 kilometers above the lunar surface and about 200 kilometers apart. At that point, regional changes in the Moon’s gravity field will cause them to accelerate or slow down, which will change the distance between them; the changes in distance will allow mapping of the gravity field. With that information, it will be possible to deduce features at or below the Moon’s surface and may help explain why the far side of the Moon is more rugged than the side that faces Earth.

BBC: Yet another Soyuz rocket launch has failed. After liftoff from Russia’s Plesetsk spaceport on Friday, 23 December, the Soyuz-2 vehicle was unable to put a communications satellite into orbit. It is one of several failed attempts this year, including Phobus-Grunt in November and the Progress cargo spacecraft, which was to take supplies to astronauts aboard the International Space Station, in August. Russia’s problems could severely impact the US, which depends on Russian rockets to carry astronauts to the International Space Station, writes Will Englund for the Washington Post. In his overview article, Englund notes how Russia has tripled its science spending over the past 10 years, “but innovation is losing out to exhaustion, corruption and cronyism.” Twenty years after the collapse of the Soviet Union, Russia is still struggling to bounce back.

Talking Points Memo: The Mars rover Curiosity, which launched 26 November aboard NASA’s Mars Science Laboratory, has switched on one of its instruments in flight. During Curiosity’s eight-month trip, its radiation assessment detector (RAD) will monitor high-energy atomic and subatomic particles from the Sun, distant supernovas, and other sources. The rover also will monitor radiation on the surface of Mars after its August 2012 landing. One of 10 precision instruments on board, “RAD is serving as a proxy for an astronaut inside a spacecraft on the way to Mars,” according to a NASA news release from RAD’s principal investigator Don Hassler, from the Southwest Research Institute in Boulder, Colorado. “The instrument is deep inside the spacecraft, the way an astronaut would be. Understanding the effects of the spacecraft on the radiation field will be valuable in designing craft for astronauts to travel to Mars.”

Nature: Out of the 2326 exoplanets identified so far by NASA's Kepler space telescope, between one-third and one-half of them are in the emerging and perhaps most numerous "super-Earth" category. Bigger than Earth but smaller than Neptune, they contradict conventional models of planet formation. Early planet-formation models used our own solar system as an example and were based on the idea of core accretion. Dust in a star's protoplanetary disk aggregates into small cores of rock and ice. Whereas the inner part of the disk doesn't contain enough material for the cores to grow much larger than Earth, cores farther out can form planets 10 times as massive as Earth. Those outer planets attract large volumes of gas to become Jupiter-like gas giants. After the detection of Jupiter-sized exoplanets with orbits as short as a few Earth days, the model was revised to allow those planets to move closer to their star after forming farther out. But that modification still doesn't account for super-Earth-sized planets that have not become gas giants or gotten swallowed up by their star. No current theory can explain how super-Earths can orbit so close to their stars.

National Geographic: The ions that make up the solar wind can collide with the Moon's surface, essentially sandblasting it in a process called sputtering. During coronal mass ejections (CMEs), the Sun throws off intense bursts of plasma at up to a million miles per hour in a cloud that's several times the size of Earth. Normal solar wind consists mostly of lightweight protons from hydrogen atoms that have been stripped of their electrons, but CMEs contain a much higher percentage of heavier ions such as helium, oxygen, and iron. The heavier atoms collide with the Moon with much greater momentum than protons do, and they can dislodge more material from its surface. William Farrell, leader of the Dynamic Response of the Environment At the Moon (DREAM) team at NASA's Goddard Space Flight Center in Maryland, and colleagues created a model of the process that predicts that between 100 and 200 tons of lunar material could be blasted off the lunar surface by a large CME.

Washington Post: The search for Earth-like planets circling other stars is escalating, with NASA’s $600 million Kepler mission having found 2326 candidate planets, of which 207 are similar in size to Earth. Ten of those, which includes the latest find—Kepler-22b—orbit their stars in the so-called habitable zone, a balmy band of space where water can be liquid. With a surface temperature of about 22 °C, Kepler-22b, located some 600 light-years from Earth, looks to be the best candidate so far. It orbits a star very similar to our own Sun and its year is almost the same length as Earth’s, said Natalie Batahla, a Kepler scientist. Whether Kepler-22b has a surface and an atmosphere is yet to be determined, however; more observations need to be made with other, ground-based telescopes. According to Batahla, “We are getting really close; we are really homing in on the true Earth-sized habitable planets.”

Nature: Astronomers have discovered the two most massive black holes known in the universe to date, writes Ron Cowen for Nature. Using instruments on the Keck II and Gemini North telescopes on Hawaii’s Mauna Kea, Chung-Pei Ma (University of California, Berkeley) and colleagues found that a cluster galaxy called NGC 3842 houses a black hole with a mass equivalent to 9.7 billion Suns and that another galaxy, NGC 4889, has a black hole with an estimated mass of at least 20 billion Suns. The previous record holder has a mass of 6.7 billion Suns. The galaxies are about 300 million light-years from Earth—relatively close by cosmic standards. Because supermassive black holes formed early in the universe, the team’s findings, published this week in Nature, suggest that the two newly discovered black holes could represent a missing link to the brightest quasars from early cosmic times. Also, because of their unusually large mass, they may have evolved differently from smaller black holes.

Space.com: Scientists have been puzzled by the discovery of a number of ancient stars that contain unusually high levels of heavy elements such as gold, platinum, and uranium, because the heaviest elements are usually found at those levels only in much later generations of stars. Helium, hydrogen, and lithium were the first elements to form in the early universe. Heavier elements, up to iron in the periodic table, formed later inside stars. And the heaviest elements formed in supernovae. After a few hundred million years, all the known chemical elements existed, but the oldest stars that are still around today should contain only a fraction of the amount of heavy elements seen in the Sun and younger stars. Using data from the Nordic Optical Telescope (NOT), astronomers from the Niels Bohr Institute in Copenhagen and Michigan State University have found evidence to support one of two theories that seek to explain the anomaly. In one theory, the anomalous enrichment came from the stars' binary companions. In the other theory, which is more consistent with the NOT data, the enrichment comes from a previous generation of stars that seeded the local interstellar medium. “What this tells is how new elements and new stars formed in infant galaxies and why the sun, planets and we ended up having the chemical composition we do,” said Terese Hansen, lead author on a paper published in Astrophysical Journal Letters.

BBC: A colony of Caenorhabditis elegans survived for six months aboard the International Space Station, produced 12 generations of offspring, and have now returned to Earth. The millimeter-long worms were the subjects of a study, by Nathaniel Szewczyk of the University of Nottingham and colleagues, on physiologic changes caused by low-Earth-orbit conditions. An automated chamber allowed for remote observation and kept the worms alive and healthy in a liquid environment without human intervention. Automated experimental systems like this one could be used in unmanned expeditions to study the effects of interplanetary travel on physiology, with the eventual goal of finding out whether human colonization of other planets is possible.

Space.com: Researchers studying the black hole Cygnus X-1, which is part of a binary-star system, have reported the most detailed look yet at one of the strongest x-ray sources seen from Earth. Using data collected by the Very Large Baseline Array and other instruments, the team has calculated the distance to Cygnus X-1, the mass of the black hole, and its extreme spin. Fifteen times as massive as the Sun, the black hole spins quickly yet progresses slowly through the galaxy. From such information, the team is beginning to piece together information about the black hole’s state today and draw conclusions about its origins, writes Nola Taylor Redd for Space.com.

Washington Post: Not only does Jupiter’s smallest moon, Europa, have a massive global ocean beneath its icy surface, but it could also have huge lakes, according to new research. One of the geological mysteries of the solar system, writes Brian Vastag for the Washington Post, has been the number of icebergs strewn across the surface of Europa. Now researchers have found that they are probably the tips of subsurface lakes that well up and warm the surface. That is good news for scientists hoping to find signs of life on Europa because it means that there could be channels through the ice for life forms to travel between the surface and the ocean. If such subsurface lakes exist on Europa, they would hold more water than all five Great Lakes, said Britney Schmidt from the University of Texas at Austin and a coauthor of a recent paper published in Nature. It may be a while, however, before funding for another probe to Europa comes through, since much of the US space budget is being earmarked for the James Webb Space Telescope.

BBC: China’s Shenzhou 8 spacecraft returned to Earth today, after a 17-day mission in which it performed the nation’s first docking maneuvers with China’s mini space lab, Tiangong 1. Beijing sees the dockings as the next phase in its step-by-step approach to acquiring the skills of human spaceflight operations, writes Jonathan Amos for the BBC. China aims to launch a manned mission in 2012. By 2020 it hopes to start building a 60-ton space station, considerably smaller than the 400-ton International Space Station but a remarkable achievement for a single country nevertheless.

New York Times: Today a Soyuz TMA-22 rocket carrying one American and two Russian astronauts began the two-day flight to the International Space Station (ISS). Now that its space shuttle program is over, NASA is going to utilize other sources of transport for space travel, among them Russia and, eventually, commercial enterprise. Today's launch was originally scheduled for September, but was delayed after the failure of a Russian unmanned cargo rocket in August. Another crew of three astronauts is scheduled to travel to the ISS on 21 December.

Discovery News: The largest cluster of sunspots since 2005 is now visible from Earth. Known as AR (active region) 1339, it's 100 000 kilometers wide, and several of the spots in the cluster are bigger than Earth. On 3 November it erupted in a large flare that created waves of ionization in Earth's upper atmosphere and disrupted radio communications on Earth about 45 minutes later. The cluster has since begun to lose magnetic complexity, and any flares it produces will probably be moderate in size. AR 1339 will be facing Earth for approximately two weeks.

Space.com: Despite a successful launch yesterday, Russia’s Phobos-Grunt spacecraft is stuck in Earth orbit after its thrusters failed to fire and send it on toward Mars. Engineers now have about three days to figure out what went wrong and fix the problem. After that time, Phobos-Grunt’s batteries will run out and the spacecraft will become just another piece of space debris orbiting Earth. China also has a stake in the venture because its first Mars probe, Yinghuo 1, is attached to Phobos-Grunt. This is Russia's third attempt to send a probe to the Martian moons; the other two missions, launched by the USSR in the 1980s, ended in failure.

NPR: Over the past half century, plutonium-238 has powered such NASA robotic spacecraft as Voyager 1 and 2, Cassini, and New Horizons, which have traveled to Jupiter, Saturn, and beyond. Although not the same plutonium isotope that is used for bombs, plutonium-238 was only produced in the US during the cold war years. Now the US, whose supply of ²³⁸Pu made it the only country to have sent spacecraft beyond Mars, is running out of the fuel and has not made plans to produce more. In the past, NASA, which uses ²³⁸Pu, has split the bill with the Department of Energy, which makes and handles the material. But Congress is balking at allocating the requested funding to DOE. Little time remains: The supply is expected to run out by 2022, and experts predict that production of new plutonium won’t be fully up and running before 2020.

Nature: After some 15 years, Russia is attempting to reignite its space program with the 8 November launch of its Phobos-Grunt spacecraft. The mission is two-pronged: to carry out scientific measurements on the surface of Phobos, the larger of Mars's two moons, and to bring back to Earth a few hundred grams of pebbles and dust collected from the moon’s surface. From the soil sample, scientists hope they will also find particles of material from Mars that they think could have been ejected from the planet’s surface by asteroid bombardment some 4 billion years ago. They also hope to use the material to determine Phobos’s age and origin and to see whether it contains any organic matter. "The major outcome is that Russia might establish its credibility again," said Roald Sagdeev, a former director of the Space Research Institute in Moscow who is now at the University of Maryland in College Park.

BBC: Astronomers using the Fermi Gamma-ray Space Telescope have spotted the youngest and brightest millisecond pulsar ever. Located about 27 000 light-years away in the Sagittarius constellation, the pulsar lies within a globular cluster, a dense spherical field of hundreds of thousands of old stars held together by gravity, writes Jason Palmer for the BBC. Because of the amount of light given off by the cluster, the single pulsar had to be very bright to be seen, which is unusual as pulsars tend to be very weak. This one was shining in the highest-energy light we know of: gamma rays. The researchers predict a short lifetime for J1823−3021A, however, as it is spinning down quickly—meaning the pauses between its beam pulses are growing longer and longer. Because this is the first gamma-ray pulsar that scientists have seen, it's not yet known whether they are rare or whether their detection simply awaited the right equipment—gamma-ray telescopes. The Fermi collaboration published its results online yesterday in Science.

BBC: The third and final stage of the 520-day Mars500 experiment has concluded, with all six members of its international crew in good health. The experiment was conducted to gather data on the physiological and psychological effects of the extended isolation involved in a flight to Mars. The crew lived and worked in a mockup windowless spacecraft and had limited contact with the outside world; to simulate the actual communications lag between Mars and Earth, a time delay of up to 25 minutes was imposed on all communications. The crew's hormone levels, sleep patterns, and moods were monitored. Tentative discussions have begun between the partners of the International Space Station about doing an isolation experiment in orbit.

MSNBC: Researchers have proposed a novel way of detecting extraterrestrial life: looking for artificial illumination. They hypothesize that if humans light up their cities at night, perhaps other beings do as well. In a paper submitted to the journal Astrobiology, Abraham Loeb of Harvard University and Edwin Turner of Princeton University suggest looking at the change in light from an exoplanet as it moves around its star; if the orbit is elliptical, the amount of reflected light will change with the distance from its star, but the amount of artificial light should remain constant. Unfortunately, at present, Earth’s day side is some 600 000 times brighter than its night side. For the method to work, any artificial brightness of the night side would have to be comparable to the natural brightness of the day side. Nevertheless, as radio-based searches have yet to turn up any sign of intelligent life on other worlds, and as new and better telescopes are being deployed, searching for brightly lit alien cities may one day prove viable.

Baltimore City Paper: Yesterday the US Senate approved full funding of the James Webb Space Telescope through its 2018 launch. As reported earlier, the JWST project, the successor to the Hubble Space Telescope, has been plagued with cost overruns and delays. Although the Republican-dominated House of Representatives had proposed cutting its funding, Senator Barbara Mikulski (D-MD) has proven its biggest advocate and pushed hard to keep it in the Senate's version of the budget. “The Webb Telescope supports 1200 jobs and will lead to the kind of innovation and discovery that have made America great,” she said. “It will inspire America’s next generation of scientists and innovators that will have the new ideas that lead to new products and new jobs.” The next hurdle will be keeping JWST funding alive as part of reconciling the Senate and House versions of the 2012 budget.

Guardian: With the successful launch of its prototype space-delivery vehicle, Shenzhou 8, China has taken another step toward building its own space station. Within the next two days, Shenzhou 8 should dock with the Tiangong 1 module, which was launched about a month ago. The docking involves some difficult maneuvers that will prove a further test of China’s space readiness. "Mastering the technology of rendezvous and docking will lay a firm foundation for China to build a space station," said Zhou Jianping, the chief designer of China's manned space engineering project.

Astronomy: A new study has found that dark matter in dwarf galaxies is distributed smoothly rather than being densely clumped at their centers as the standard cosmological model had predicted. Dwarf galaxies are believed to be about 99% dark matter. Matt Walker from the Harvard–Smithsonian Center for Astrophysics and Jorge Penarrubia from the University of Cambridge determined the positions and velocities of thousands of stars in two Milky Way neighbors, the Fornax and Sculptor dwarf galaxies. From their measurements, the researchers inferred the dwarf galaxies' dark matter distributions and concluded that either normal matter affects dark matter more than scientists thought, or dark matter isn’t as cold and slow-moving as previously predicted. Their findings will be published in an upcoming issue of the Astrophysical Journal.

Science: Space weather forecasters have begun using a new system that improves their ability to predict solar storms and reduces the potential timing error of their predictions from 15 hours to 6. The new system was developed by a consortium of 11 institutions led by Boston University, and was refined by the National Oceanic and Atmospheric Administration's Space Weather Prediction Center (SWPC) in Boulder, Colorado. It includes a computer simulation that calculates how a coronal mass ejection (CME) will move out from the Sun and interact with interplanetary conditions on its way to Earth. Solar storms can degrade GPS navigation, induce blackouts, and disable or damage satellites; more accurate forecasting allows for better preparation in advance.

New Scientist: As a potential cost-cutting measure, the US Defense Advanced Research Projects Agency (DARPA) has proposed recycling parts of dead satellites that are in graveyard orbit. The agency estimates that billions of dollars’ worth of satellites, many of them retired due to obsolescence or failure, are currently orbiting Earth. DARPA’s Phoenix program would draw on diverse techniques, such as remote operating procedures and remote imaging, gleaned from non-space-related activities like surgery and offshore drilling, to harvest parts that could still be useful. A first test mission is planned for 2015 during which a robot would use remote sensing to collect parts and reconfigure them for a new purpose. However, old satellites are not necessarily just up for grabs—according to the Outer Space Treaty dating from the late 1960s, any object launched into space remains the property of the country that launched it.

ABC News: Astronomers using the W. M. Keck Observatory's telescopes on Hawaii’s Mauna Kea have taken the first direct image of a planet being formed, writes Audrey McAvoy for the Associated Press. Until now young planets had been difficult to detect because the stars they orbit are so bright. Adam Kraus of the University of Hawaii and Michael Ireland of Australia’s Macquarie University overcame that obstacle by altering the shape of the telescope’s mirror and masking most of its surface. According to Kraus and Ireland, the planet is being formed from dust and gas circling a 2-million-year-old star, about 450 light-years from Earth. Their observations should help further the study of planetary science by determining when and where planets form in relation to the stars they orbit.

Nature: The European Space Agency (ESA) will begin testing the Galileo navigation system on 20 October with the launch of two navigation satellites. Galileo will eventually consist of 27 operational and 3 spare satellites in three orbital planes and will broadcast on a wider range of frequencies than either the US GPS system or the Russian GLONASS system. It's anticipated that Galileo will augment information from the other two systems, with its wider bandwidth providing more accurate measurements of Earth's surface features. ESA anticipates that enough satellites will be in orbit to provide some services by 2015, with the full constellation in orbit by the end of the decade.

Nature: The European Space Agency (ESA) has begun negotiations with Russia for a rocket to launch the first stage of ExoMars, in 2016, in exchange for Russian participation in the mission. The first stage of the mission will carry an orbiter designed to find possible sources of methane and other trace gases that could indicate the presence of microbial life on Mars. The orbiter would serve as a data relay for a rover, launched in 2018, that would collect Martian soil samples. A separate mission would carry those samples back to Earth for study. NASA officials had initially promised an Atlas V rocket for the 2016 launch, but they informed ESA earlier this year that budget problems would prevent them from doing so. They still intend to provide a rocket for the mission's second stage in 2018.

Ars Technica: When Earth first formed, it was dry; water came from meteorites and other bodies that collided with Earth afterward. Until recently only one type of meteorite had been found to have hydrogen and oxygen isotopes that matched those found in our oceans. Now, however, Paul Hartogh of the Max Plank Institute and colleagues have found a comet that has the same isotopes in the same ratio as Earth's oceans. Named 103P/Hartley 2, it currently orbits Jupiter, but probably originated in the Kuiper belt just outside the orbit of Neptune. The discovery greatly increases the number of candidates that could have brought ocean-like water to Earth.

New Scientist: Four apps have won a place on a satellite called Strand-1. The winning apps were announced today by mission planners at the UK's Surrey Satellite Technology Ltd and the Surrey Space Center. The nanosatellite, measuring just 30 x 10 x 10 cm and weighing only 4 kg, features an Android-based smartphone. The phone's accelerometers and GPS receivers will form the heart of the satellite's guidance system, writes Paul Marks for New Scientist. One app, Scream in Space, which will run videos of people screaming on the phone’s display, aims to see whether vibrations from the phone’s loudspeaker can be picked up through its chassis by a microphone. Other apps will take pictures of Earth using the phone’s camera, measure variations of Earth’s magnetic field with the satellite’s onboard magnetometer, and use the phone’s screen to display telemetry data on the satellite’s progress through space. Designers hope to piggyback Strand-1 on a rocket launch sometime between January and April 2012.

MSNBC: NASA has announced its next voyage of discovery, not into space but 18 meters beneath the surface of the Atlantic Ocean. That neutral-buoyancy environment approximates the near-weightless conditions astronauts would encounter on an asteroid. Shannon Walker, a NASA astronaut who lived and worked on the International Space Station for five months in 2010, will lead the crew.

The main objective of the 13-day mission, set to start 17 October, is to test the techniques needed to explore near-Earth asteroids, such as anchoring to an asteroid's surface, moving around on a surface without gravity, and deploying data-collecting instruments. This will be the 15th trip of NASA's extreme environment operations group; previous missions have rehearsed moonwalking, assembling space station modules, and making visits to Mars.

Science: Space weather is expected to become more severe over the next few decades, partly as the Sun's activity changes. Frequent flyers and astronauts will face greater radiation hazards as a result.

In times of higher activity, the Sun emits solar energetic particles (SEPs) more consistently, but at the same time generates a strong magnetic field that shields Earth against galactic cosmic rays (GCRs). Right now, the Sun has been declining to a new minimum, from a peak in about 1920. At this minimum more GCRs will reach Earth. However, although there are fewer SEP events, those that do occur are more intense. Frequent fliers are at increased risk because the thin air at high altitudes doesn't give much protection from space weather. Astronauts, especially those traveling to the Moon or beyond, would face more potential problems; expected radiation doses from a roundtrip to Mars would increase at least twofold. This may limit space travel to Mars until 2050 at the earliest.

MSNBC: The Tiangong 1, or "Heavenly Palace," is an eight-ton unmanned space lab that will function as a test bed for China's developing space technologies. The main task of the lab will be to experiment with rendezvous and docking between spacecraft; it's scheduled to rendezvous and dock with an unmanned Shenzhou 8 spacecraft a few weeks after launch. China's space program has been compared, in its level of technological development, to that of NASA's Gemini program, which launched 10 manned flights between 1965 and 1966.

Tiangong 1 will launch from a site in the Gobi Desert around September 27–30.

Science: At the end of their lives, massive stars much larger than our Sun tend to detonate as supernovae. Smaller stars, called main-sequence stars, prolong their leave-taking, by changing from small, yellow, hot stars to larger, cooler, reddish-colored stars more commonly known as red giants.

A red giant is a fate scheduled for our star, the Sun, about five billion years from now. At that time the Sun's expansion will engulf at least Mercury and Venus.

Whether Earth will survive is open to question. If the Sun loses enough of its outer layers, then Earth will be in a wider and therefore (temporarily) safer orbit. However, the changing gravitational tides caused by the Sun's expansion could draw Earth close enough to get swallowed up and eventually broken into pieces.

Although that may be the end of Earth, it will not be the end of the Sun. Red giants eventually collapse into dense small stars called white dwarfs.

As the Sun passes from red giant to white dwarf, it will shed its outer atmosphere. Again with the changing gravitational fields, planets formerly too distant to support life could migrate closer, to within the so-called habitable zone, the point at which water can be liquid and conditions are suitable for life.

Some white dwarf stars show evidence of having disks of rocky debris that may be the remains of planets; those disks could eventually coalesce to form a second generation of rocky planets close enough to the dying star to have habitable temperatures for billions more years—enough time for life to potentially evolve again.

Universe Today: Early this morning a Soyuz spacecraft returned three astronauts to Earth from the International Space Station (ISS). After nearly six months in space, Alexander Samokutyaev, Andrey Borisenko, and NASA flight engineer Ronald Garan touched down safely in the southern steppes of Kazakhstan. For the next two months the ISS will be maintained by the three remaining astronauts, until the next three-person crew will arrive. Flights to and from the ISS were disrupted after a freighter carried by a Soyuz rocket crashed to Earth in August. Russia has been working to determine exactly how and why the rocket crashed.

The Guardian: The European Southern Observatory's High Accuracy Radial Velocity Planet Searcher (HARPS) aided in the recent discovery of 50 new exoplanets, and one of them could support life. Named HD85512b and situated in the constellation Vela about 35 light-years away, the exoplanet orbits a star at a distance that should allow liquid water to exist on its surface. The planet's mass is 3.6 times that of Earth's, and estimated temperatures range from about 30 °C to 50 °C. More than 50% of the planet would need cloud cover to be habitable. HD85512b is the second exoplanet discovered so far that could support terrestrial life.

National Geographic: On a recent close flyby of Saturn's moon Dione, NASA's Cassini spacecraft revealed traces of the moon's passage left in Saturn's magnetic field—evidence of the moon's atmosphere. Dione doesn't have sufficient mass to retain an atmosphere on its own, so the thin layer of air exists only because it's constantly being replenished. The moon resides within Saturn's belt of highly energetic particles and those particles cause Dione's surface ice to break apart chemically, which releases molecules that become the moon's atmosphere. Since that ice is mostly water ice, the atmosphere may be mostly oxygen. Existing data from other Cassini instruments, as well as data gathered during the next flyby on 12 December, may provide clues to whether this is so.

NPR: On Saturday NASA launched a pair of probes to measure the Moon’s gravity and core. Grail-A and Grail-B, part of the Gravity Recovery and Interior Laboratory mission, were launched together aboard a small Delta II rocket but will travel independently to the Moon. The probes will take a leisurely four months to reach their destination in order to save fuel, protect their instruments, and reduce the spacecraft's velocity on arrival. The Grail spacecraft, each of which is the size of a washing machine, won't land on the Moon but will conduct their research from low lunar orbit of about 55 km above the surface. "We will learn more about the interior of the moon with Grail than all previous lunar missions combined," said Ed Weiler, head of NASA's science mission directorate.

Space.com: NASA does not have enough astronauts, according to a report released yesterday by the National Research Council. The agency has advised that NASA step up its recruitment to be sure to have enough trained personnel to anticipate attrition due to illness or injury and to accommodate possible new missions. The American astronaut program has been steadily decreasing in size since 1999, from 150 members to the current 61, partly due to the retirement of the space shuttle. However, the US still needs astronauts to fly missions to the International Space Station. The ISS training regime is extensive and requires years of preparation, including training for spacewalks, learning software systems, and mastering docking procedures.

New York Times: Zinc and bromine in a rock that was collected from the rim of Mars’s Endeavour crater and examined by NASA’s Opportunity rover suggest that Mars’s geology may have been formed with heat and water, writes Kenneth Chang for the New York Times. Opportunity, one of a pair of rovers of NASA’s Mars Exploration Rover Mission, has been searching for signs of past water on Mars’s surface since 2004. The crater’s rim consists of rocks that were lifted up from below its surface as the result of a long-ago impact. The scientists are especially interested in using Opportunity to get a close-up look at clay deposits there that were detected from orbit by NASA’s Mars Reconnaissance Orbiter. Such deposits could lend further support to the theory that Mars used to be warmer and wetter. Opportunity—“a very senior rover that’s showing her age,” according to project manager John Callas—has far outlived its original mission and covered much more ground than it was designed to do.

MSNBC: With the use of a powerful supercomputer, a team of researchers has produced the first realistic simulation of the formation of the Milky Way galaxy. Researchers at the University of California, Santa Cruz and the University of Zürich took advantage of 1.4 million processor-hours on NASA's Pleiades supercomputer, as well as additional supporting simulations at the Swiss National Supercomputing Center. The simulation, which took 9 months, involved tracing the motions of some 60 million particles over more than 13 billion years. According to the research team, the difficulty is in getting the simulations to match up exactly with observations. "Our result shows that a realistic spiral galaxy can be formed based on the basic principles of the cold dark matter paradigm and the physical laws of gravity, fluid dynamics, and radiophysics," said Lucio Mayer of the University of Zurich, coauthor of a paper describing the simulation, to be published in the Astrophysical Journal.

Space.com: A newly discovered galaxy 1.7 billion light-years away has captured astronomers’ attention because of its unique combination of characteristics. Speca is only the second spiral, as opposed to elliptical, galaxy known to generate large, powerful jets of subatomic particles that rush from its center at nearly the speed of light. It is also one of only two galaxies to have shown such activity in three separate episodes. The jets are produced by a supermassive black hole at Speca’s center. "This is probably the most exotic galaxy with a black hole ever seen. It has the potential to teach us new lessons about how galaxies and clusters of galaxies formed and developed into what we see today," said the study's principal investigator, Ananda Hota, of the Academia Sinica Institute of Astronomy and Astrophysics in Taiwan. Hota and colleagues have published their results in the Monthly Notices of the Royal Astronomical Society.

New Scientist: Researchers at Swinburne University of Technology in Melbourne, Australia, have detected a pulsar with an orbiting object that may be composed of diamond. Using the CSIRO Parkes radio telescope in New South Wales, Matthew Bailes and coworkers detected the pulsar in December 2009. From follow-up observations taken with the Lovell radio telescope in the UK, they surmise that the orbiting object has a mass comparable to Jupiter’s but less than half its width. The extremely fast rotation of the pulsar and the size and density of the companion object led the researchers to conclude that the object is all that's left of a star whittled down by the pulsar. Because the core of a stripped-down star would be mostly carbon, and because it would be under high pressure due to its own gravity, they believe the carbon would crystallize—most likely into diamond, much as carbon does deep inside Earth. The researchers published their results yesterday in Science.

Los Angeles Times: For the first time, astronomers say they've borne witness to a supermassive black hole consuming a star, writes Amina Khan for the Los Angeles Times. On 28 March a detector on the Earth-orbiting Swift observatory picked up a sudden burst of radiation from a point in the constellation Draco, 4.5 billion light-years away. Typically the gamma-ray bursts that Swift was designed to detect are one-time events caused by an exploding star. In this instance, however, subsequent bursts were detected from the same spot, which convinced the researchers that the origin was not a supernova exploding. David Burrows of the Pennsylvania State University and colleagues have proposed instead that a star about the same size as our Sun ended up too close to the black hole, which caused the side of the star nearest the black hole to stretch toward it, in much the same way that the Moon causes the tides on Earth. As the gravitational forces shredded the star, chunks of its plasma streamed toward the black hole, and some of the material was expelled into a jet of high-energy radiation. That jet was likely responsible for the mysterious burst detected in March. The astronomers say they were lucky to witness the event—the jet of radiation just happened to blast straight toward Swift, like a flashlight beamed in the face. Their results were published yesterday in Nature.

BBC: According to vast computer simulations of debris thrown up from asteroid impacts on Earth, more life-bearing particles could have been scattered to Mars, Jupiter, or even beyond our solar system than previously thought. Mauricio Reyes-Ruiz of the National Autonomous University of Mexico and his colleagues have carried out the largest-ever simulations of the process, which considered impacts of varying intensity. Because of new and better computing systems, the researchers were able to study the effects over much longer time periods, up to millions of years. The most important question, however, is whether any ejecta could carry living cargo. The researchers think so, as such small, hardy organisms as water bears have already demonstrated their ability to survive the harsh conditions of space. Preliminary results were presented at January’s American Astronomical Society meeting.

Space.com: NASA’s Dawn spacecraft, launched in September 2007, arrived last month at the asteroid Vesta and will spend a year circling it before moving on to arrive at the even larger asteroid Ceres in 2015. The first spacecraft to visit an asteroid in the asteroid belt between Mars and Jupiter, Dawn will study Vesta in four phases from different orbits. Each orbit should yield surface images in visible and IR wavelengths from the mapping spectrometer on board; the images will allow the science team to produce geologic and compositional maps of Vesta’s surface. Ultrasensitive measurements of the spacecraft’s motion, made using radio signals, will help researchers better understand Vesta’s gravity field. Ceres and Vesta were chosen because they are two contrasting protoplanets, Ceres being icy and Vesta rocky. Ultimately, by studying those two large bodies in the asteroid belt, researchers hope to gain more information about the formation of the solar system.

National Journal: Tuesday’s solar flare may be responsible for knocking out high-frequency radio-communications systems in the Middle East, according to Joe Kunches, a scientist with the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center. NASA, which eyeballed Tuesday's solar flare with its Solar Dynamics Observatory satellite, described it as the largest of the current 11-year solar cycle and said it was three times bigger than the previous large flare in February, writes Bob Brewin for National Journal. The Space Weather Prediction Center uses a number of satellites to develop its forecasts, which can alert people to the flares and allow them to take action to preserve power grids and other high-tech assets. Kunches, who said Tuesday’s was the largest flare since 2006, declined to predict what space weather would be like in 2013, when the current solar cycle is expected to peak.

New York Times: As scientists report today in Science, Mars may have liquid water flowing on its surface. They base their theory on the observation of fingerlike streaks up to five yards wide on some of the planet’s steep slopes. The streaks, which appear to grow and shift in summer and fade in winter, showed up on high-resolution photographs taken by NASA’s Mars Reconnaissance Orbiter, which arrived at Mars in 2006. Principal investigator Alfred McEwen of the University of Arizona and colleagues surmise that any water on Mars’s surface would have to be extremely salty in order to stay liquid at such cold temperatures. The possible presence of liquid water is certain to revive speculation that Mars is teeming with microbial organisms, writes Kenneth Chang for the New York Times.

NPR: To explain why the two sides of the Moon are so different from each other—the near side is low and flat and the far side is mountainous and deeply cratered—two researchers have made a novel proposition. They propose that Earth originally had two moons, the one familiar to us now and a smaller, sister moon. At some point before life on Earth began, the smaller moon collided with the larger one at a relatively low speed, which caused the smaller one to break up and spread out over the Moon’s surface, forming mountains on the far side. Erik Asphaug and Martin Jutzi of the University of California, Santa Cruz, who conducted computer simulations to test their theory, have published their results in Nature. "I think this idea is going to get a lot of attention because it's very novel, it's very clever, and people are going to be interested in testing to see whether it's right or wrong," said Maria Zuber from MIT.

Science: On 18 July the Russian orbital radio telescope Spektr-R was finally launched, writes Daniel Clery for Science. Originally designed in 1982, the satellite was put on hold following the collapse of the Soviet Union. The goal of the Russian satellite is to work with ground-based radiotelescopes to create images of unprecedented precision. Spektr-R aims to study the structure and dynamics of radiosources both inside and beyond our galaxy, shedding light on the structure of galaxies, star formation, black holes, dark matter, and interstellar space.

NASA: Scheduled to launch late this year, NASA's next Mars rover, Curiosity, will land at the foot of a mountain inside the planet's Gale crater sometime in August 2012. “Curiosity not only will return a wealth of important science data, but it will serve as a precursor mission for human exploration to the Red Planet,” said NASA administrator Charles Bolden. Researchers will use the rover's tools to study whether the landing region had favorable environmental conditions for supporting microbial life and for preserving clues about whether life ever existed. To choose the site, more than 100 scientists considered the safety concerns and scientific attractions of some 30 different locations.

NPR: When the space shuttle was first proposed more than 40 years ago, NASA told Congress and the public that it would put payloads into orbit at a significantly lower cost than any other launch vehicle. In reality—because of the technology of the time, the size of the vehicle, and design compromises that increased the complexity of the shuttle—each shuttle launch cost more than $1.5 billion, and the program required 35 000 people to service and maintain the vehicles. This morning as the space shuttle program came to a close with Discovery’s final landing in Florida, NPR's David Kestenbaum investigates how much it really costs to put a payload into orbit. Elon Musk, founder of a new launch competitor, SpaceX, claims its rockets can launch payloads into near-Earth orbit at a cost of $1000–$3000 per pound. Although the cost is significantly lower than the shuttle's, which was about $10 000 per pound, Musk believes it is still too expensive and is working to bring it down to $100 per pound.

NASA: Some 5 billion km from Earth, a fourth moon has been found orbiting Pluto. Using the Hubble Space Telescope, astronomers discovered it while they were searching for rings around the icy dwarf planet. The new moon, temporarily designated P4, is Pluto’s smallest, with an estimated diameter of 13–34 km. By comparison, Pluto’s largest moon, Charon, is 1043 km across, and Nix and Hydra are each 32–113 km across. "This is a fantastic discovery," said Alan Stern of the Southwest Research Institute in Boulder, Colorado. Stern is principal investigator of NASA’s New Horizons mission, scheduled to fly through the Pluto system in 2015. "Now that we know there's another moon in the Pluto system, we can plan close-up observations of it during our flyby," he said.

Space.com: The final space shuttle launch took place this morning. NASA's Atlantis began its 12-day mission to the International Space Station with a successful lift-off from Florida's Kennedy Space Center around 11:26am EDT. Some 750 000 to 1 million eager spectators showed up for the historic event. The four-astronaut crew will deliver about 9500 pounds of cargo and several science experiments to the station. "Good luck to you and your crew on the final flight of this true American icon. Good luck, Godspeed, and have a little fun up there," shuttle launch director Mike Leinbach told the astronauts just before launch.

New York Times: With the aid of the European Space Agency’s Herschel Space Observatory, researchers have studied a massive cosmic dust reservoir created by a supernova almost 25 years ago, writes Sindya Bhanoo for the New York Times. “We are looking at the sky at wavelengths that have never been observed before,” said Mikako Matsuura, an astronomer at University College London and lead author of a study published in Science. The supernova occurred some 160 000 light-years away when an aging star’s core collapsed. Matsuura and her team reported that the explosion generated enough cold dust to form more than 200 000 Earths. By studying the dust using Herschel and other telescopes, the researchers hope to better understand how galaxies, including the Milky Way, are formed.

New Scientist: Yesterday, in a draft 2012 budget for NASA and other government agencies, a congressional committee proposed canceling the James Webb Space Telescope. The Commerce, Justice, Science, and Related Agencies Subcommittee, which creates a draft budget for NASA each year, announced in a press release that it proposed to terminate funding because the telescope "is billions of dollars over budget and plagued by poor management." To go into effect, the draft budget will need to be approved by the entire Appropriations Committee, the House of Representatives, the Senate, and President Obama.

Daily Mail: Earlier this month a robotic lander successfully flew up to 7 feet for 27 seconds during testing at NASA's Marshall Space Flight Center. The lander, about the size of a golf cart, is powered by a green propellant, hydrogen peroxide. The test proved the lander could execute commands autonomously, such as hover for an extended period, control its position and orientation, and land successfully. Such unmanned vehicles are being designed to perform science and exploration research on the surface of the Moon and other airless bodies, including near-Earth asteroids, where aero-braking and parachutes won't work.

Science: Many planets with an atmosphere have a faint illumination or glow that can be seen on the horizon. Apollo 8 astronaut James Lovell saw something similar when his spacecraft went around the Moon in 1968, but the Moon has no atmosphere to catch the Sun's rays and create such a spectacle. Data collected by the Lunar Ejecta and Meteorites (LEAM) experiment, placed on the Moon in 1972, suggested that lunar dust was picking up an electric charge from cosmic rays or the solar wind to drive it high into the lunar sky and cause the glow. But now former Apollo physicist Brian O'Brien, who helped design dust monitors for several of the Apollo spacecraft, argues in Planetary and Space Science that much of the LEAM data were not detections of charged lunar dust particles but instead electrical interference generated by the Apollo Lunar Surface Experiments Package (ALSEP) instruments parked 7.5 meters away from LEAM. A final answer may be provided by NASA’s Lunar Atmosphere and Dust Environment Explorer, which launches in 2013.

Washington Post: Scientists now believe that Saturn's moon Enceladus may have a vast ocean beneath its surface. Measurements taken by the Cassini-Huygens spacecraft during 2008 and 2009 flybys have shown large grains of ice with substantial amounts of salt spewing from the bottom of the moon. Frank Postberg of the University of Germany, lead author of a study published today in Nature, and colleagues think the ice grains are coming from surface fractures at the moon's southern pole, areas that have been deemed "tiger stripes." That the stripes are the apparent source of salty ice is considered a significant breakthrough with implications for understanding planets and moons and for detecting possible sites hospitable to life, writes Marc Kaufman for the Washington Post.

CNN: Using NASA's Chandra X-ray Observatory, scientists have determined that at least 30 million black holes had formed before the universe was 1 billion years old, quite early in the universe's 13.7-billion-year history, writes Elizabeth Landau for CNN. Black holes are dense regions in space that have collapsed in on themselves; material in their vicinity gets drawn in, and as they devour that matter, they emit x-ray radiation. No one knows how the first black holes were formed after the Big Bang, nor which came first: the galaxy or the black hole. The Chandra observations indicate that proto-galaxies already had central black holes, but black holes and their galaxies appear to be growing together. In addition, "all the black holes we see at the centers of galaxies today are in a way descended from those baby black holes we see at the dawn of the universe," said Kevin Schawinski of Yale University and coauthor of a study published in Nature. He and his coworkers plan to push even further into the early universe to gain more insights into the early black holes.

Space.com: Launched in 2007 to study Vesta and Ceres, the two most massive members of the asteroid belt, NASA’s robotic spacecraft Dawn is already sending back scientifically significant photos of Vesta, even though the spacecraft is not scheduled to enter the second largest asteroid’s orbit until next month. The images reveal several intriguing features, including a dark blotch about 97 km wide near the equator of the 530-km-wide Vesta. Dawn will orbit and study Vesta for one year, then move on to investigate the dwarf planet Ceres. Dawn will be comparing the two giant bodies, which were shaped by different forces, and scientists hope it will help unlock the secrets of our solar system’s early history.

Nature: Saturn's icy moon Enceladus has some of the chemical ingredients for life—liquid water, organic carbon, and nitrogen—plus a source of energy in its tectonically active crust. As Nature's Richard Lovett reports, a recent workshop held at the SETI Institute in Mountain View, California, attendees brainstormed ideas for finding life on Saturn's sixth-largest moon. Although the Cassini spacecraft is currently in orbit around Saturn and has flown by Enceladus 27 times so far, it lacks the instruments to detect the molecular signatures of life. One promising approach is to look for differences in the concentrations of carbon-12 and carbon-13 in methane and other molecules. Whereas biochemical reactions favor the lighter isotope, nonbiochemical reactions favor neither isotope.

BBC: Mars grew to its present size in about three million years, which may explain why it is about one-tenth the mass of Earth, writes Jennifer Carpenter for the BBC. It probably stayed relatively small because it avoided colliding with planetary building material during the development of our solar system. Nicholas Dauphas of the University of Chicago and Ali Pourmand of the University of Miami in Florida used the ratio of the radioactive elements hafnium-176 and hafnium-177 to estimate how long it took Mars to form: between two million and three million years—a short time compared with the tens of millions of years it took Earth to reach its current size. They think that Mars was already at its current size before dissipation of the nebular gas, when Earth was just beginning to form.

Washington Post: Six years ago, the Japanese spacecraft Hayabusa landed on the near-Earth asteroid 25143 Itokawa and retrieved a sample. A capsule containing the sample landed on Earth last summer. NASA has just announced plans for a similar mission. In 2016 the billion-dollar OSIRIS-REx spacecraft will begin its four-year journey to the near-Earth asteroid RQ36. Once OSIRIS-REx is in orbit around the asteroid, mission planners will identify a suitable landing site. As the Washington Post's Brian Vastag explains, planetary scientists want to analyze asteroid material because of its possible relevance to the origin of life on Earth. Ground-based spectroscopic measurements indicate that RQ36 contains carbon-bearing materials. If the same materials made it through the asteroid belt and landed on Earth, they might have provided a key ingredient for life, carbon.

BBC: An international team of astronomers has used the results from a major astronomical survey to confirm the existence of dark energy, estimated to make up about 74% of the total mass–energy of the universe. The WiggleZ Dark Energy Survey, which was carried out August 2006–January 2011, used data from NASA’s Galaxy Evolution Explorer and the Anglo-Australian Telescope to map the distribution of some 200 000 galaxies and look back in time about 8 billion years. The astronomers used two separate kinds of observation to provide an independent check on previous dark-energy results, writes Paul Rincon for the BBC. The concept of dark energy was first invoked in the late 1990s to reconcile the measured geometry of space with the total amount of matter in the universe and to explain why the universe appears to be expanding at an accelerating rate.

Nature: Today a team of scientists in Europe released the results of a €3 million ($4.3 million) design study on the Einstein Telescope (ET), writes Eugenie Samuel Reich for Nature. The telescope, scheduled to be constructed around 2025, would represent the third generation of gravitational wave detectors. The first generation includes the US's Laser Interferometer Gravitational-Wave Observatory (LIGO), already in operation, and the second includes Advanced LIGO, which will not go online until around 2015. The €1 billion ($1.4 trillion) ET observatory will continue the search for gravitational waves and their sources, thought to include such dramatic astrophysical events as the merger of black holes or neutron stars. Such large ripples in spacetime, which were first predicted by Einstein's theory of general relativity, have yet to be directly detected. The new telescope, which will be 10 times as sensitive as Advanced LIGO, also offers the potential to probe the earliest moments of the universe just after the Big Bang.

Science: A long-running debate on whether free-floating planets really exist and how common they are may now be resolved, writes Jon Cartwright for Science. A new study by Takahiro Sumi of Osaka University in Japan and colleagues lists 10 objects in our galaxy that are very likely "homeless" planets and posits that such planets are more common than main-sequence stars, outnumbering them by nearly two to one. The team used a technique called gravitational microlensing to measure changes in the brightness of distant stars, whose light is bent and magnified by the gravity of planets passing in front of them. Smaller planets create shorter magnification times. The team found 474 incidents of microlensing, just 10 of which were brief enough to be planets of around Jupiter's size, while the other 464 microlensing events were due to bigger objects such as brown dwarfs. One question arising from the study is how the free-floaters formed. According to one explanation, they used gravity to draw in nearby material such as the asteroids and protoplanets in our solar system. Sumi and his colleagues think it's more likely that they began their lives in planetary systems and were subsequently thrown out of orbit.

Ars Technia: The red dwarf Gliese 581, only 20 light years from Earth, is host to at least five planets, three of which have been considered potentially habitable. The latest addition to this list is GJ581d, writes John Trimmer for Ars Technica. The planet is a super-Earth that was previously thought to support neither liquid water nor enough of an atmosphere to produce a significant greenhouse effect. Although GJ581d lies at the far edge of the star's habitable zone, it's still close enough for tidal locking to ensure that only one side of the planet ever faces the star. The planet's poles and far side are therefore extremely cold; below a certain temperature an atmosphere collapses as its constituents freeze out. Robin Wordsworth of the Institut Pierre Simon Laplace in Paris and colleagues have developed a general circulation model (GCM) that can be applied to a range of planets. In the case of a planet like GJ581d, the team found that denser atmospheres lead to horizontal heat transport and a greenhouse effect strong enough to keep the atmosphere intact and allow for surface temperatures above the melting point of water. Although it's not known whether GJ581d has a dense atmosphere, Wordsworth and his team have devised a test. Using their model, the team synthesized emission spectra that could be compared to real spectra once they become available.

Nature: The hole in the ozone layer over Antarctica is starting to heal, say researchers in Australia, who have published their findings in Geophysical Research Letters. Thanks to the Montreal Protocol of 1989, which banned the use of chlorofluorocarbons and other ozone-destroying chemicals, levels of anthropogenic ozone depleters detected in the region's stratosphere have been falling since around the turn of the millennium, writes James Mitchell Crow for Nature. Before Murry Salby, an environmental scientist at Macquarie University in Sydney, Australia, and his colleagues could investigate manmade ozone depletion, however, they first had to account for the naturally occurring annual fluctuation in ozone levels. The researchers found that average springtime levels are linked to changes in a particular pattern of stratospheric weather known as dynamical forcing. Once they figured that out, they were able to detect the gradual recovery of the ozone levels, which had declined precipitously until the late 1990s before beginning a slow rebound. A complicating factor in predicting future ozone levels will be the influence of climate change, said David Karoly, a climate scientist at the University of Melbourne, Australia.

BBC: Io, one of Jupiter's moons, is the most volcanic body in the solar system; it erupts 100 times more lava a year than does Earth, writes Jonathan Amos for BBC News. A reassessment of data from NASA's Galileo probe suggests that this is due to a reservoir of magma at least 50 kilometers thick that probably makes up at least 10% of the moon's mantle by volume. Unlike Earth, where volcanoes tend to collect at the boundaries of tectonic plates, Io has volcanoes all over its surface. Jupiter drives this volcanism by producing tides on the moon that squeeze and pull Io's body, melting its rocks. In turn, Io dramatically distorts Jupiter's magnetic field, although it wasn't until several years after Galileo made its passes of the moon that physicists were able to determine why. The conductivity of rocks high in magnesium and iron increases by orders of magnitude when they melt; that conductivity was what allowed Io to influence its parent planet's magnetic field so strongly.

Nature: Vesuvius has been dormant since a small eruption in 1944, writes Katherine Barnes for Nature, but it could be more dangerous than previously assumed. Seismic imaging studies have detected an unusual layer 8–10 kilometers deep under the mountain's surface. Giuseppe Mastrolorenzo and Lucia Pappalardo, of the Vesuvius Volcano Observatory in Naples, Italy, think this is an active magma reservoir, which could produce large-scale explosions even larger than the one that destroyed Pompeii, with pyroclastic flows traveling up to 20 kilometers. Geological evidence shows that such a blast occurred about 3800 years ago and covered the whole of present-day Naples. The Vesuvius observatory team has therefore urged Neapolitan authorities to base their emergency plan on a worst-case eruption. However, Bruno Scaillet, of the University of Orléans in France, and colleagues believe that Vesuvius has become less explosive over time, with magma chambers migrating upward. The 1944 eruption came from a relatively shallow level 3 kilometers below the surface; magma stored there is probably less viscous and therefore less prone to causing large explosions.

Science: Rumors have been circulating for several months via the internet, Italian media, and word of mouth that Italian scholar Raffaele Bendandi had predicted the destruction of Rome today by a catastrophic earthquake. Rome is not a city prone to earthquakes, and there is no evidence that Bendandi—who did accurately predict an earthquake in central Italy in January 1924—ever made such a prediction. Nonetheless, growing apprehension has led thousands in the city to stay home from work or travel to the countryside. An estimated 20% more city employees have called in sick or requested vacation time today when compared with the same day last year. Italy's National Institute of Geophysics and Volcanology has attempted to allay residents' fears by posting educational videos on YouTube and by pointing out that scientists are not able to predict when and where an earthquake of a certain magnitude will strike. Gabriele Scarascia Mugnozza, director of the department of Earth sciences at Sapienza University of Rome, will hold a meeting on earthquakes today in his department in an attempt to convince secondary school students and other members of the public that improved construction techniques and detailed geological investigations, rather than pinpoint prediction, are the best ways of dealing with earthquakes.

Space.com: Next August, if all goes to plan, NASA's car-sized rover Curiosity will touch down on the Martian surface and begin its mission: to determine whether Mars is or was ever hospitable to life. The person responsible for the mission's success is project manager Peter Theisinger of the Jet Propulsion Laboratory in Pasadena, California. In a Q&A with Space.com's Mike Wall, Theisinger describes the technical challenges he and his colleagues had to contend with, notably ensuring that the rover lands safely and upright. Comparing Curiosity with its two famous predecessors, Theisinger answered,

Spirit and Opportunity were geology missions. They were looking for signs of water, and they found it. This is taking the next step forward: to look at more detailed chemistry and mineralogy, and to see if there were true habitability possibilities, and to search for organics as well.

Wired: A swarm of earthquakes, all below two on the Richter scale and many too small to feel, hit Maine's eastern coast between 30 April and 5 May. Residents called local authorities to report the sound of gunshots and unexpected blasting, but what they had heard was the sound of Earth's crust buckling. The region is in the middle of a tectonic plate; although it experiences several earthquakes a year, swarms are rare. The last two took place in 2006 and 1967. They, along with the most recent one, were caused by Earth's crust springing back from the Laurentide ice sheet—between one and two miles thick, it pressed the crust underneath down 500 feet. Although the ice sheet has long since melted, the crustal rebound process is still taking place.

National Geographic: A study by Robert Jackson, of Duke University, and colleagues, has found evidence that methane has escaped into ground and drinking water in areas where shale gas drilling was under way. Shale gas is extracted via hydraulic fracturing, or "fracking"; water is pumped into rock deep underground until the resulting pressure causes the rock to crack, which in turn releases the natural gas within. The researchers found methane in the majority of water wells they sampled. They analyzed methane concentrations in 60 ground-water wells across Pennsylvania and New York and found explosive concentrations of the gas as far away as 3200 feet from an active drilling site. Average methane concentrations in wells near drilling sites were 17 times those in wells where shale gas drilling had not occurred. Methane isn't regulated in drinking water because it doesn't alter color, taste, or odor, nor does it affect water's potability. However, it is an asphyxiation and explosion hazard in confined spaces.

Science: The thick nitrogen-rich atmosphere of Saturn's largest moon, Titan, may have been blasted into existence 3.8–4 billion years ago, during the appropriately named Late Heavy Bombardment period. Most planets and moons in the solar system were pounded by large numbers of comets, asteroids, and other large objects at that time, and they may have impacted Titan's surface with enough energy to chemically strip apart the ammonia-rich ice there. Yasuhito Sekine, a scientist at the University of Tokyo in Kashiwa, Japan, and colleagues tested this hypothesis by firing tiny, laser-accelerated particles of gold, platinum, and copper at various speeds into mixtures of frozen ammonia and ice. Their experiments suggest that the heat and pressure generated at impact speeds greater than 5.5 kilometers per second are enough to break down ammonia ice into nitrogen, hydrogen, and water vapor. If Titan had a primordial atmosphere, it would have been destroyed by the bombardment and replaced with ammonia-derived nitrogen. If it had no atmosphere to begin with, the number and size of impacts expected for the moon would have been sufficient to generate the amount of nitrogen that exists in its atmosphere now.

National Geographic: A planet close to Earth's size and in orbit around a Sun-like star, 55 Cancri e has the density of lead and is the hottest known rocky world. Residing in a five-planet system within the constellation Cancer, 55 Cancri e is 42 light-years away. First discovered in 2004 via ground-based telescopes, the planet's orbit has now been shown to be 17 hours and 41 minutes long, one-quarter of the original estimate of 2.8 days. This February, Jaymie Matthews of the University of British Columbia and colleagues used Canada's Microvariability and Oscillations of Stars (MOST) space telescope to measure the tiny dips in starlight as the planet passed in front of its star. Its 17-hour orbit means that it's about 20 times closer to its star than Mercury is to Sol. The brightness of the host star meant that MOST was able to determine the planet's size and mass—60% larger and eight times more massive than Earth. Astronomers' understanding of the planet is still developing; just this week, a second team independently reported that the planet's radius may be up to a third larger than the value reported by the MOST team. Both teams agree that whatever its actual radius, 55 Cancri e is a new class of planet.

Guardian: Agricultural practices evolved over a period of about 11 000 years of stable climate, but now they will need to adapt to a changing climate and an increase in global population, writes Damian Carrington for the Guardian. In a recent study, David Lobell, Wolfram Schlenker, and Justin Costa-Roberts found that global productivity of crop plants has dropped, increasing food prices by 18.9% over recent decades. The drop in productivity was not due to changes in rainfall; rather, higher global temperatures caused dehydration, prevented pollination, and slowed photosynthesis. The researchers used computer models to separate the effects of climate change from natural variations in weather and other factors. Between 1980 and 2008, wheat production was 5.5% lower than it would have been without global warming, and corn production was 3.8% lower. Some countries' production dropped far more; Russia lost 15% of its potential wheat crop, and Brazil, Mexico, and Italy all suffered above-average losses.

Chronicle of Higher Education: Oceanographers used to rely on military submarines to gather data on the salinity, temperature, and other properties of the seawater beneath Arctic ice. Now, a new means has been developed: instrument-laden robotic submarines known as seagliders. About the size and shape of a car-top cargo box, seagliders can determine their own courses to sample a range of depths and locations. The data they collect are transmitted back to the lab via satellite when the seagliders surface. Each unit costs about $150 000.

Science: The National Geophysical Research Institute (NGRI) in Hyderabad, India, will launch a 30-month project to create an earthquake observatory in Koyna, a region in western India that experiences frequent small to moderately sized earthquakes. An 8-kilometer-deep borehole will be drilled and laced with sensors that measure chemical, electrical, and gravitational perturbations. Koyna's borehole will be unique because it will be the first intraplate borehole—three similar ones drilled thus far are all on the boundaries of tectonic plates—and because it will be near a large dam, where the rise and fall of reservoir water levels often induces earthquakes. Concerns that drilling could increase regional seismicity and thus pose a risk to the nuclear power plant in Maharashtra, 64 kilometers away, have been dismissed as unrealistic: Earthquakes in the region are triggered by water in the many thousands of water-filled cracks in the earth, and seismologists believe that one more hole will not have any significant effect.

Space.com: A liquid-water ocean may lie beneath the icy surface of Saturn’s moon Titan, according to new evidence collected by NASA’s Cassini spacecraft, writes Mike Wall for Space.com. In orbit around Saturn since 2004, Cassini has provided considerable data, including information about Titan’s rotation and orbit. The new data reinforce earlier suppositions about a possible below-surface ocean. In a new study that will appear in the journal Astronomy and Astrophysics, lead author Rose-Marie Baland of the Royal Observatory of Belgium in Brussels and colleagues theorize that Titan is not a completely solid body, but rather that it has a solid interior surrounded by a liquid-water ocean and all enclosed in an icy shell. In addition, the possible presence of water leads the researchers to believe that Titan could support some form of life. "Astrobiologists do not really know yet what are the necessary conditions for life to emerge, but it seems that the presence of water is a requirement," said Baland.

Nature: Since the 1960s, probes with heated tips have been used to bore through ice, but they have their problems and limitations: Dirt and sediment would often build up at the head of the probe and impede the transfer of heat, and most of the probes could only move downward through layers of ice. After two years of work, Bernd Dachwald, of Aachen University of Applied Sciences in Germany, and colleagues have developed IceMole, a new type of ice-melting probe that is capable of pulling itself through ice layers—not only downward but also horizontally and upward. A 6-cm screw at its head allows the probe to keep in contact with the ice it is trying to melt. The probe easily penetrates dirt and should also be able to function where the ice is in a near vacuum. A French team has already expressed interest in using the probe to search for micrometeorites in ice; it could prove useful for everything from sampling Antarctic subglacial lakes to searching for indications of subsurface water on icy outer moons such as Europa.

New Scientist: Four science teams—from Europe, Australia, China, and the US—are racing to retrieve the first million-year-old sample from Antarctica’s ice. Ancient ice could hold clues to past changes in Earth’s climate. Using such ice samples, scientists could study the concentration of carbon dioxide in the ancient atmosphere by analyzing the air trapped in tiny bubbles within the ice. A decline in carbon dioxide concentration could explain the advent of an ice age, for example. One researcher, Robin Bell of the Lamont-Doherty Earth Observatory of Columbia University, and her colleagues have come across a potential problem with the hunt, however. They have found that ice sheets in Dome A, one of the drilling sites, is growing from the bottom up. This could mean that any ancient ice that was once there has melted and been replaced.

National Geographic: The tornado that devastated Tuscaloosa, Alabama, on Wednesday was the result of an unusual confluence of meteorological conditions. Current estimates put the twister's wind speed at about 260 mph, and it may have remained in contact with the ground for more than 200 miles. An unusually strong jet stream over the region, with wind speeds of 150 mph, caused intense upward motion in the atmosphere. The colder, drier air within combined with the warm, moist air already in place to create rotating thunderstorms known as supercells—one of the few types of storms that spawn tornadoes. A 50 mph wind closer to the ground only increased the storms' rotation. Wednesday's tornado outbreak included more than 100 twisters across 6 states and killed at least 283 people, making it the worst outbreak since 3 April 1974, when 330 people were killed in an area that stretched from Alabama to Indiana.

BBC: In 2007 the Intergovernmental Panel on Climate Change (IPCC) predicted that increased greenhouse gas concentrations would lead to a weakening of the Atlantic Meridional Overturning Circulation, which includes the Gulf Stream. The result would be cooler temperatures in Europe. A group of researchers who have just published a new study in Nature say, however, that changes to another ocean current, the Agulhas Current, could keep Europe warm even if the Gulf Stream switches off. The Agulhas Current flows southward down the eastern coast of Africa, and although most of the water heads east back into the Indian Ocean, some of it leaks around Africa’s southern tip—Cape Agulhas—and flows into the Atlantic. One of those researchers, Lisa Beal from the Rosen School of Marine and Atmospheric Science in Miami, Florida, said that research on the current to date has been sparse but that wind shifts farther south make it likely that the Agulhas Leakage is increasing. "This could mean that current IPCC model predictions for the next century are wrong and there will be no cooling in the North Atlantic to partially offset the effects of global climate change over North America and Europe," said Beal.

Science: In a recent report, an eight-member panel convened by the National Earthquake Prediction Evaluation Council, which advises the US Geological Survey (USGS), concluded that the New Madrid fault system is at significant risk for severe earthquakes. Quakes along the 150-mile-long fault can potentially threaten the US states of Illinois, Indiana, Missouri, Arkansas, Kentucky, Tennessee, and Mississippi. The panel recommended that construction in those states should continue to meet quake-resistant standards. But seismologists debate the degree of risk. Recent GPS measurements of land shifts show that very little crustal deformation has occurred in the area. Seth Stein of Northwestern University believes that the lack of crustal deformation indicates that stress in the New Madrid fault has wound down and that consequently there is little risk of earthquakes. The USGS advisory panel, however, wasn't sanguine about taking that evidence as proof of reduced risk to the area and will stick with its assessment, at least until more data become available.

Nature: A piece of space debris as small as one centimeter long can cause serious damage to vital weather, communication, or missile-warning satellites, and the amount of debris orbiting Earth is increasing. The Space Surveillance Telescope, a ground-based telescope developed by the US Defense Advanced Research Projects Agency (DARPA), took its first images in February; after it passes an evaluation, it will be added to the US Space Surveillance Network.

The telescope’s 3.5-meter aperture and three-mirror system make it more powerful and faster than other ground-based telescopes in the network; it can collect data on dimmer objects more quickly and can scan the sky several times in one night. It will focus on the region about 35 000 km from Earth, where objects in geosynchronous orbit reside. The telescope will not be available for use in scientific experiments, but a subset of the data may be made available on a website operated by US Strategic Command, and researchers may be able to get further data on request.

National Geographic: All planets in our solar system with both a magnetic field and a significant atmosphere have auroras; on Earth, Jupiter, and Saturn they give off distinct radio emissions in addition to visual displays. Jonathan Nichols of the University of Leicester in the UK and colleagues say that radio telescopes are now becoming sensitive enough to detect radio signals from auroras of planets up to 150 light-years from Earth.

He and his team found that radio signal detection would be most useful for finding rapidly spinning, Jupiter-size planets that orbit stars shining brightly in ultraviolet UV wavelengths. According to Nichols, the best chance for detecting these planets lies with the Low Frequency Array (LOFAR)—which scans the night sky in low radio frequencies—due to its large collecting area and frequency range.

Various: Powerful electrical currents flow between Saturn and its sixth-largest moon, Enceladus. The Cassini spacecraft, since its arrival at Saturn in 2004, has passed the 500-km-wide moon 14 times and has gathered more data each time. Jets of gas and ice from Enceladus's south pole become electrically charged, forming an ionosphere. The motion of the moon and its ionosphere through the magnetic bubble that surrounds Saturn acts like a dynamo, which in turn creates the currents. Cassini's UV imaging spectrograph spotted a patch of UV light in Saturn's upper atmosphere near its north pole that indicated the presence of an electrical circuit; the Cassini Plasma Spectrometer's electron spectrometer (CAPS-ELS) detected the electron beams. The process observed between Saturn and its satellite may be a universal one; Jupiter and its moon Io have a similar electrical current between them that appears to develop through a comparable process.

Science: Pluto's atmosphere has expanded dramatically since 2000, when it extended about 135 km above the surface. It now extends more than 3000 km—nearly one-quarter the distance to Charon, its largest moon. The atmosphere's composition has changed as well; carbon monoxide has been detected in addition to the methane that was previously known to surround the orb. Because instruments in previous studies could have detected carbon monoxide, its appearance probably indicates a new stage in the seasonal development of Pluto's atmosphere. The unanticipated changes may be related to Pluto's recent close approach to the Sun or to long-term variations in the Sun's ultraviolet output. Because the dwarf planet was discovered a mere 80 years ago, we have yet to observe the entirety of its 248-year path around the Sun.

BBC: The massive solar flare of 15 February was caused by five rotating sunspots working in concert. Sunspots are centers of intense magnetic activity on the Sun's surface; solar flares occur when some of that magnetic energy is released over a period of minutes to tens of minutes. The sunspots involved in February's flare rotated through as much as 130 degrees as they developed, and they injected enough energy into the Sun's atmosphere to produce the largest flare seen in more than four years. The flare and its resultant coronal mass ejection (CME) caused no significant disruption to electronic communications or other infrastructure, despite their size. CMEs can cause disruption to satellites and telecommunications, but the alignment between Earth's magnetic field and that of the CME itself dampened the potential effects.

BBC: The Yellowstone Caldera feeds the hot springs, mud pots, and geysers associated with Yellowstone National Park. Seismic images created in 2009 of the subterranean molten plume showed it dipping downward from Yellowstone at a 60-degree angle and extending about 150 miles west-northwest to a point about 410 miles underground, under the Montana-Idaho border. Michael Zhdanov and colleagues at the University of Utah in Salt Lake City have used electrical conductivity to create new images of the plume; they found that it dips less steeply, at about 40 degrees, and extends about 640 miles from east to west. The two sets of images may look different because they measure different things; seismic images highlight materials that slow seismic waves, and geoelectric images highlight fluids that conduct electricity. The difference may indicate that there are more fluids underground than previously thought, and that the smaller region imaged by seismic waves may be enveloped by a broader region of partly molten rock and other liquids.

BBC: The Intergovernmental Panel on Climate Change predicted in 2007 that sea levels will rise at least 28 cm by 2100. That is a global average, and now a Dutch team is attempting to study the possible regional variations. Ocean currents and differences in the temperature and salinity of sea water are among the factors that cause mean sea level to vary by up to a meter across the oceans—those factors do not include short-term changes due to tides or winds, writes Richard Black for the BBC. So whatever the global figure for rising sea level turns out to be, there will be regional differences. According to the team's projections, New York will see the biggest increase from the global average, with Vancouver, Tasmania, and the Maldives also experiencing above-average impacts.

Inside Science News Service: The largest earthquake on record was the magnitude-9.5 Chile earthquake of 1960. It accounts for about a quarter of the total seismic strain released worldwide since 1990. The magnitude-9.0 quake in Japan on 1 March released one twentieth of the global total. Richard Aster, of the New Mexico institute of Mining and Technology, says that we may be in the middle of a period of large earthquakes after a lull in the 1980s and 1990s. Global seismic data show periods of relative quiet, with fewer large earthquakes, as well as spikes of activity. The records only go back to the beginning of the 20th century, so there is uncertainty about what, if anything, the clusters of large quakes might mean. Andrew Michael, a geophysicist at the US Geological Survey in Menlo Park, California, has concluded that the overall pattern of large earthquake occurrences is random, once aftershocks are removed from the data.

Science: Comets were once thought to be pristine repositories of the building blocks of our solar system. The most recent challenge to that belief comes from new analyses of the comet Wild 2. Planetary scientist Eve Berger of the University of Arizona and her colleagues have found several different sulfur-containing minerals in microscopic pieces of the comet, including a form of cubanite that is created only in liquid water below 210 °C. They conclude that the alteration most likely occurred when heat—from an impact or radioactive decay—melted pockets of ice within the comet, which then refroze. Primordial material left over from the formation of the solar system may still be out there, but scientists are having some difficulty finding it. That challenge only increases their desire to obtain a piece of comet to analyze.

Science News: Although fresh water has always mixed with salt water as glaciers melt and rivers empty into oceans, researchers report that they have been studying a large expanse of the Arctic Ocean where such sea-ice melt and river inflows have effectively pooled with little mixing for the past dozen years. An unusual and persistent pattern of clockwise winds has corralled at least 7500 cubic kilometers of fresh water within the Beaufort Gyre off northern Canada, reports Laura de Steur, a physical oceanographer with the Royal Netherlands Institute for Sea Research in Texel. The freshwater pool is roughly twice the volume of Africa’s Lake Victoria, one of the largest freshwater bodies in the world. The concern is that a large release of fresh water into the north Atlantic Ocean could alter the flow of the North Atlantic Current, which could lead to a cooling of winter temperatures in portions of the Northern Hemisphere.

Space.com: Yesterday researchers announced the discovery of a new mineral, Wassonite, found in a 4.5-billion-year-old meteorite discovered in Antarctica in 1969. "Wassonite is a mineral formed from only two elements, sulfur and titanium, yet it possesses a unique crystal structure that has not been previously observed in nature," NASA space scientist Keiko Nakamura-Messenger said in a statement. The mineral’s name honors John T. Wasson, a UCLA professor known for his achievements across a broad swath of meteorite and impact research. Meteorites may contain information about the formation of our solar system.

CNN: Ozone depletion has now reached the highest level observed to date in the northern hemisphere. The World Meteorological Organization stated Tuesday that the Arctic region lost 40% of its ozone layer from the beginning of this winter to late March. The usual winter ozone loss there is about 25%; the highest ozone loss previously recorded was approximately 30%. Although cuts in the production of chlorofluorocarbons and other ozone-destroying chemicals have been made, and the concentration of them in the atmosphere is slowly falling, the chemicals stay in the atmosphere for several decades. When temperatures in the stratosphere fall below −78 °C, chemical reactions turn the ozone-destroying chemicals into highly reactive substances that break apart the three oxygen atoms of ozone, leading to an ozone hole.

Science: Daily computer simulations indicate that the radioactive water being released by the Fukushima power plants is still restricted, for the most part, to areas near the coast. The International Atomic Energy Agency asked the SIROCCO group, at the University of Toulouse in France, to run its SYMPHONIE-NH ocean model centered on the Fukushima plant. Daily simulations are posted on SIROCCO's website. The site cautions that these models are only meant to provide "scenarios of dispersion" and not quantitative data on radioactivity in the sea. However, the models thus far confirm what oceanographers thought would be the case: The highest concentrations of radionuclides in the modeling thus far are within about 5 kilometers of the shore.

BBC: Mark Showalter of California's SETI Institute, Matthew Hedman of Cornell University, and their respective colleagues have come up with an explanation for why Jupiter’s and Saturn’s rings appear rippled. Showalter's team analyzed images of Jupiter's rings taken by the Galileo and New Horizons spacecraft. Hedman's team analyzed images of Saturn's rings taken by the Cassini spacecraft. Their analyses, published yesterday in Science, suggest that the ripples were caused by debris, most likely from a comet, tilting the ring relative to the planet's equatorial plane and then leaving a spiral pattern behind as it passed through. As time goes by, the ripples become more closely spaced, providing a means to deduce when the original impact occurred.

National Geographic: For the first time, scientists are planning to drill all the way through Earth's kilometers-thick crust to the planet's deep, hot mantle and retrieve samples, writes Richard Lovett for National Geographic. The samples, they say, would rival Moon rocks for sheer scientific import—and be nearly as hard to get. Until now, suitable technology was lacking. But better knowledge of Earth's shell and technological advances—for example, a Japanese drill ship equipped with 10 kilometers of drilling pipe—have put the goal within reach, according to a commentary in this week's issue of Nature, cowritten by Damon Teagle, a geologist at the University of Southampton in the UK. Mantle rocks would tell us much about Earth’s origins and history, says Teagle.

Daily Mail: Quartz—the second most abundant mineral on Earth—could help scientists predict earthquakes and volcanic eruptions, according to a recent study. Underground quartz deposits are abundant wherever fault lines occur and indicate a weakness in Earth’s crust that is likely to lead to a geological event. Marta Pérez-Gussinyé from the University of London and geophysicist Anthony Lowry from Utah State University published their findings in Nature on 16 March.

New York Times: Besides the much-reported aftermath in Japan, last Friday’s earthquake also caused global effects: It moved Japan’s coastline, tilted Earth’s axis slightly, and shortened the length of the day. Japan is “wider than it was before,” said Ross Stein, a geophysicist at the US Geological Survey. Global positioning stations closest to the epicenter jumped 4 meters closer to the US. The earthquake also shifted Earth’s figure axis—the axis that Earth’s mass is balanced around—by 16 cm where it intersects the surface of the planet. By shifting the planet’s mass closer to its center, the earthquake also caused Earth’s rotation to speed up, shortening the day by 1.8 microseconds. None of this is unusual, however. “The Earth is always wobbling, and the length of the day is always changing,” said Richard Gross, a scientist at NASA’s Jet Propulsion Laboratory.

New Scientist: Earlier this week, a panel convened by the National Academy of Sciences issued its latest Planetary Science Decadal Survey, which lists in order of scientific priority the missions that NASA should undertake in the decade 2013–22. The top slot went to the Mars Astrobiology Explorer-Cacher (MAX-C), which seeks to land on the Martian surface and return to Earth with rock samples. The Jupiter Europa Orbiter (JEO), which would survey Jupiter's icy moon, came in second, followed by the Uranus Orbiter and Probe. Each of the top three missions is expected to cost several billion dollars. If NASA can't find the money, the panel recommends that some missions be delayed or replaced with cheaper ones.

BBC: A team led by Eric Rignot of NASA's Jet Propulsion Laboratory and the University of California, Irvine, has just published the results of a 20-year study into the extent and causes of global sea-level rise. The gradual warming of Earth's lower atmosphere raises sea levels in two ways—by warming seawater, thereby lowering its density, and by melting icecaps and glaciers, thereby increasing the amount of seawater. Until recently, the warming of seawater was the bigger contributor. Now, however, the melting of ice has taken the lead. On average, sea levels now are rising at a rate of 3 mm a year.

Washington Post: NASA has taken the unusual step of disclaiming any endorsement of a paper written by one of its scientists, Richard Hoover of Marshall Space Flight Center in Huntsville, Alabama. The paper, which appears in the online Journal of Cosmology, claims that tiny, wormhole-like cavities in the Alais, Ivuna, and Orgueil meteorites constitute evidence of extraterrestrial bacteria. As Seth Borenstein of the Associated Press reports, other scientists are skeptical, given how easily the meteorites could have become contaminated. "There has been no one in the scientific community, certainly no one in the meteorite analysis community, that has supported these conclusions," NASA Astrobiology Institute Director Carl Pilcher said of Hoover's analysis.

Independent: Scientists say that the magnetic north pole is moving. For two centuries it has been located in Canada, but it is currently relocating toward Russia at a rate of about 40 miles per year. The speed of its movement, having increased by a third in the past decade, has prompted speculation that the field could be about to "flip," which would cause compasses to invert and point south rather than north, something that happens between three and seven times every million years. Geologists believe that the magnetic north pole moves around due to changes in Earth's molten core, which contains liquid iron. Although the shift will affect compasses, it will not affect GPS systems, which rely on satellites.

Space.com: A pea-sized piece of the Allende meteorite that crashed in Mexico in 1969 is helping astronomers better understand the early days of our solar system and could shed light on planet-formation processes in general. The sample they looked at was a calcium-aluminum-rich inclusion; scientists believe such inclusions were among the first solids to condense from the swirl of gas and dust as the planets were forming. By measuring the concentrations of two different oxygen isotopes in the various layers—oxygen-16 and oxygen-17 varied from place to place while the solar system was forming—the team learned much about the inclusion’s travels. The team reports its results today in Science.

Science: Although species naturally come and go over long periods of time, a new study says that Earth’s creatures are on the brink of a mass extinction, the sixth in its history, writes Ann Gibbons for Science. A mass extinction is defined as when three-quarters of all species vanish quickly, such as the dinosaur disappearance 65 million years ago after an asteroid struck Earth. Conservationists have warned for years that we are in the midst of a human-caused extinction, with species from frogs to birds to tigers threatened by climate change, disease, loss of habitat, and competition for resources with nonnative species. The study’s lead author, Anthony Barnosky of the University of California, Berkeley, says, "This is really gloom-and-doom stuff. But the good news is we haven't come so far down the road that it's inevitable." If humans work quickly to protect endangered and threatened species and their habitats now, the mass extinction can be prevented or at least delayed by thousands of years.

BBC: Nitrogen is the fourth most abundant element in the universe, the most abundant gas in Earth's atmosphere, and an essential ingredient in proteins, DNA, and other biomolecules. But getting nitrogen into the right chemical form to give rise to life is chemically tricky. Now, Sandra Pizzarello of Arizona State University and her colleagues have found a possible answer. By using hot, pressurized water, Pizzarello was able to dissolve and subsequently analyze an otherwise insoluble organic component of a meteorite found in Antarctica. Among the molecules they found was ammonia. Unlike N₂, ammonia readily participates in organic chemistry. Pizzarello speculates that meteorites could have brought ammonia to prebiotic Earth, thereby giving life the chemical impetus needed to get going. The team reported their results in the Proceedings of the National Academy of Sciences.

New Scientist: In the four-planet system KOI-730, two of the planets share the same orbit around their star. They circle their Sun-like parent star every 9.8 days at exactly the same orbital distance, one about 120 degrees ahead of the other—called the gravitational “sweet spot.” The discovery bolsters the theory that our Moon was formed about 50 million years after the birth of the solar system, from the debris of a collision between a Mars-sized body and Earth.

Guardian: The damage caused by Tuesday’s earthquake in Christchurch, New Zealand, caught many experts by surprise. The severity of the damage appears to be due to a combination of the earthquake coming from a previously unknown fault that runs beneath the city, building weakening caused by the 2010 earthquake, and the violence of the shaking because the city rests on damp sediments. "Liquefaction is a huge problem in Christchurch because the city is built on an alluvial plain, on sediments that are vulnerable to liquefaction," said John Clague, an expert in natural hazards at Simon Fraser University in British Columbia. "When shaken, these sediments transform into a liquid, causing irregular settlement of the ground, which is extremely damaging to buildings and buried structures, like water lines."

Guardian: Electricity networks and GPS satellites are increasingly vulnerable to damage by turbulent solar weather, scientists say. "This issue of space weather has got to be taken seriously," said John Beddington, the UK government's chief scientific adviser, speaking last week at the annual meeting of the American Association for the Advancement of Science in Washington, DC. A severe solar storm could damage satellites and power grids around the world, he said, leading to a "global Katrina" costing the world's economies as much as $2 trillion. The Guardian's Alok Jha explains why.

Daily Mail: Scientists at the University of Cambridge believe they have achieved the first accurate estimate of how much faster Earth's core is rotating compared to the rest of the planet. The rate—about one degree every million years—is much slower than previously thought and arises from the complex dynamic between Earth's inner and outer core, which generates Earth's geomagnetic field. Without our magnetic field, Earth's surface would not be protected from charged particles spewing from the Sun, and life would not be able to exist. The researchers' results were published in Nature Geoscience.

BBC: Three days ago, NASA's Solar Dynamics Observatory detected an ultraviolet flare emanating from a sunspot. Hot particles associated with the flare have already reached Earth. Although observations from two other spacecraft, STEREO-B and SOHO, suggest that the stream of particles is not powerful enough to knock out power grids, it will likely affect telecommunications on Earth, brighten and enlarge the polar auroras, and qualify as the strongest in four years.

Independent: If you grew up thinking there were nine planets and were shocked when Pluto was demoted five years ago, get ready for another surprise. There may be nine after all, and Jupiter may not be the largest, says Paul Rodgers for the Independent. Scientists now believe they have proof of the existence of Tyche, a gas giant four times more massive than Jupiter and orbiting at a distance 15 000 times greater than Earth's orbital radius. The proof could lie in data that have already been gathered by a NASA space telescope, WISE, and are just waiting to be analyzed.

Nature: When the James Bond movie You Only Live Twice was filmed on the slopes of Mount Shinmoedake in 1967, the Japanese volcano had been dormant for eight years and hadn't expelled lava for three centuries. As Nature's David Cyranoski reports, the volcano's current eruptions of mud and steam have surprised volcanologists—even though the volcano and the range it belongs to were being monitored with seismometers, tiltmeters, magnetometers, thermal imagers, and other instruments. Now, Japanese authorities have increased their surveillance of the volcano. A major eruption is not out of the question.

Science News: Deep within Earth, bacteria and other tiny organisms can coax the rocks around them to produce food, say researchers whose findings appear in the March issue of Geology. They have found that the mere presence of microbes triggers minerals to release hydrogen gas, which the organisms then ingest. “It looks like the bacteria themselves have an integral role in liberating this energy,” says R. John Parkes, a geomicrobiologist at Cardiff University in Wales. The work helps explain how microbes can survive up to kilometers deep in a subterranean world far from any sunlight to fuel photosynthesis.

Guardian: The first panoramic view of the Sun has been put together from images taken by NASA's STEREO mission, launched in 2006. Twin spacecraft face each other across the Sun and take photographs of its surface. The images will be used to create a three-dimensional map of the Sun. "The sun is not the smooth yellow sphere a lot of people understand it to be. It's complex, and a three-dimensional view is essential to understanding how it works," said Richard Harrison, a scientist at the Rutherford Appleton Laboratory in Oxfordshire and principal investigator for the UK cameras aboard the spacecraft.

Washington Post: New discoveries from NASA's Kepler space mission made public Wednesday and published in Nature today reveal a large number of planets deep in space, with some almost as small as Earth and others in the "habitable zones" of their solar systems where scientists think life could potentially exist, writes Marc Kaufman for the Washington Post. With about 1200 candidate planets now cataloged, Kepler has also identified a solar system with at least six small planets orbiting their sun—all lined up on a disk-like plane similar to our own.

Scientific American: The risk of a new earthquake may have increased in an area of Chile's Pacific coast that last year suffered a massive quake and tsunamis, which killed more than 500 people, a team of scientists said on Sunday. The magnitude-8.8 quake had only partly broken stresses, deep in Earth's crust in an area south of Santiago, that have been building up since an 1835 quake witnessed by British naturalist Charles Darwin. "We conclude that increased stress on the unbroken patch may in turn have increased the probability of another major to great earthquake there in the near future," the team wrote in the journal Nature Geoscience.

Nature: A Viking legend tells of a glowing "sunstone" that, when held up to the sky, revealed the position of the Sun even on a cloudy day, writes Jo Marchant for Nature. It sounds like magic, but scientists measuring the properties of light in the sky say that polarizing crystals—which function in the same way as the mythical sunstone—could have helped ancient sailors to cross the northern Atlantic. A review of their evidence is published today in Philosophical Transactions of the Royal Society B.

The Independent: Ted Nield's essay "Meteors: What Kills Also Creates" examines the long and varied history of how humans have interpreted the sometimes destructive, even calamitous, impact of meteorites that strike Earth. Hundreds of years ago, meteorites were believed to portend momentous events. In the 1980s large meteorite strikes were linked to mass extinctions. That association remains contentious. Now, writes Nield, some scientists propose that meteorites might have led to the opposite of a mass extinction: an explosion in the number of new species known as the Great Ordovician Biodiversity Event.