Planets, planets, everywhere! Astronomers have announced the discovery of 32 new planets orbiting distant stars, bringing the list of known exoplanets up to more than 400. The batch of freshly discovered worlds include four that are only five or six times the mass of Earth, an encouraging sign in the quest for a truly Earth-like world that could support life. Researcher Stephane Udry says the discovery is exciting because it suggests that low-mass planets could be numerous in our galaxy. “From [our] results, we know now that at least 40% of solar-type stars have low-mass planets. This is really important because it means that low-mass planets are everywhere, basically” [BBC News].
The discovery was made with the HARPS telescope at the European Southern Observatory’s facility in Chile. HARPS uses the so-called wobble method to detect planets, in which researchers look for the slight quiver in a star’s regular movements that indicates the gravitational tug of an orbiting planet.
Planets were found around a surprising variety of star types. Gas giant planets were found orbiting “metal-poor” stars — those lacking in elements other than hydrogen and helium — which until now had been considered unlikely places for planets to form [Washington Post]. Researchers also located four exoplanets around relatively cool, small stars known as M-class red dwarfs, and will continue to examine such stars for signs of Earth-like planets. The team expects to keep spotting planets by the dozen, says Udry: “Nature doesn’t like a vacuum so if there is space to put a planet it will put a planet there” [Reuters].
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Image: European Southern Observatory. Artist’s impression of a newly discovered planet orbiting the star Gliese 667 C, which is part of a triple star system.
With much fanfare, NASA’s lunar probe smashed into the moon this past Friday in an attempt to excavate and study hypothetical traces of lunar water ice. As planned, the probe slung an empty rocket hull into a crater at the moon’s south pole. The LCROSS probe itself then followed behind the rocket hull, snapping photos and beaming them back to Earth before smashing into the very same crater. The impact appears to have gone off without a hitch, however the crash left many disappointed since the expected 6.2-mile-high cloud of dust, which was to be analyzed for traces of ice, never materialized. So far, astronomers using ground-based telescopes and the Hubble Space Telescope in orbit have not reported seeing any ejecta plume, but have cautioned that more time is needed to be sure [SPACE.com].
At a post-impact briefing, many in the press expressed concern about the mission’s success. In response, LCROSS project scientist Anthony Colaprete outlined several reasons why the impacts may not have thrown up plumes immediately visible after the impacts, including the [impact] hitting the inner walls of the crater at an angle that ejected the impact pit dust sideways instead of straight up. “Luck plays a part in this,” he said, adding. “We have the data we need to address the questions we have and that’s the bottom line” [USA Today]. The researchers also say it’s possible that the rocket hull hit bedrock instead of loose, gravelly soil as expected, and therefore kicked up only a small debris cloud that wasn’t visible to LCROSS.
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Astronomers have found an enormous and diffuse new ring of Saturn that lies far, far beyond the rest of the planet’s famous circlets. Researchers say the new ring is comprised of debris ejected from Saturn’s outlying moon Phoebe during impact. The new discovery also solves a puzzle regarding the curious two-faced appearance of Saturn’s moon Iapetus, whose leading hemisphere is much darker than its trailing side [New Scientist].
The ring, which has claimed the title of largest known ring in the solar system, starts about 3.7 million miles from Saturn and extends outward another 7.4 million miles. Its diameter is equivalent to 300 Saturns lined up side to side. And its entire volume can hold one billion Earths…. “This is one supersized ring” [CNN], says Anne Verbiscer, coauthor of the study published in Nature. The ring has the same orbital tilt as the moon Phoebe–both are tilted at a 27 degree angle from Saturn’s main ring plane–which supports the theory that Phoebe’s ejected dust feeds the ring.
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The exoplanet Corot-7b has earned a reputation as one of the most interesting planets yet spotted outside our solar system, mostly because of its similarities to Earth: Astronomers have determined that it’s rocky, like Earth, and it’s only about five times more massive than our home planet. But the dissimilarities are just as fascinating. In the latest twist, a new study has suggested that storm fronts on Corot-7b may bring a rain of pebbles.
The alien planet is extraordinarily close to its parent star, and researchers think that it’s tidally locked so that one hemisphere always faces the star’s blasting heat. On that side, temperatures are thought to reach about 4,220 degrees Fahrenheit—hot enough to vaporize rock. So unlike the much cooler Earth, COROT-7b has no volatile gases (carbon dioxide, water vapor, nitrogen) in its atmosphere. Instead it’s atmosphere consists of what might be called vaporized rock. “The only atmosphere this object has is produced from vapor arising from hot molten silicates in a lava lake or lava ocean” [SPACE.com], says study coauthor Bruce Fegley Jr.
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Today in the innermost region of our solar system, NASA’s Messenger space probe will swoop past Mercury for the third and final time. The maneuver will give scientists a close look at the dense, iron-rich, oddball planet, and will also alter the probe’s trajectory and prepare it to begin orbiting Mercury in March 2011.
As Messenger travels within 142 miles of Mercury at 12,000 miles per hour, the spacecraft’s camera will swivel to stare at a succession of craters and other geological features…. One target will be an old 90-mile-wide crater. Another will be young 13-mile crater and a splash of light-colored soil surrounding it. A third crater of interest has materials of unusual color perhaps produced by violent volcanic eruptions [The New York Times]. When this third flyby is complete, 95 percent of the planet will have been mapped in high resolution.
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Mars has quite a bit more water than previously thought, according to a new report in the journal Science. NASA said its Mars Reconnaissance Orbiter spotted ice at five new Martian craters, likely kicked up by meteor impacts [Reuters]. It’s no surprise that the NASA orbiter found water, it’s the size of the find—twice as much as in Greenland’s ice sheet—that surprised scientists. The ice is just under the surface, so it was only visible after the recent meteor impacts.
The ice was found half way between the north pole and the equator, which is the farthest south ice has been found on Mars. Scientists believe that water once flowed across the planet, but most thought the surface had been largely dry and parched, with planet-wide dust storms, for billions of years. They had long known that water ice and carbon dioxide ice accumulated at the poles in winter, but until now, they had no idea how far from the poles the underground ice sheet extended [Los Angeles Times].
This image shows two craters with blueish ice, which—when exposed to the Martian atmosphere—sublimates over the course of 15 weeks.
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Image: NASA/JPL-Caltech/Malin Space Science Systems
While it’s not quite time to build the first lunar swimming pool, scientists do report that they’ve found the chemical signature for water all over the moon’s surface, not just in the permanently shadowed craters near the poles that recent studies suggested might harbor ice. The findings give new hope to people dreaming of a lunar settlement where astronauts could live off the land.
Evidence of both both water and a closely related molecule called hydroxyl was detected by India’s first lunar probe, Chandrayaan-1, which scientists later lost contact with. The findings were then backed up by measurements from NASA’s Deep Impact and Cassini probes, and the three teams’ papers have been published in Science.
Chandrayaan-1 scientist Carle Pieters explains that the water was easy to miss. “When we say ‘water on the moon’, we are not talking about lakes, oceans or even puddles. Water on the moon means molecules of water and hydroxyl that interact with molecules of rock and dust specifically in the top millimetres of the moon’s surface” [The Times], she says. The scientists say their measurements indicate that the moon has the equivalent of one quart of water per ton of material.
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NASA’s new Lunar Reconnaissance Orbiter has only been on the job for three months, but even while researchers were calibrating its instruments it was already making new discoveries about our moon. The orbiter swooped down above the moon’s mysterious south pole, and measured temperatures in the permanently shadowed craters that are the lowest ever detected in our solar system. It has also detected traces of hydrogen in various lunar locations, which may indicate buried water ice.
The extent of the deep freeze in the southern lunar craters surprised scientists, says lunar scientist David Paige: “Right here in our own backyard are definitely the coldest things we’ve seen in real measurements.” Temperatures there were measured at 397 degrees below zero. That’s just 62 degrees higher than the lowest temperature possible. Pluto is at least a degree warmer even though it is about 40 times farther away from the sun [AP].
Such temperatures probably allowed for the preservation of ices of water, methane, or ammonia from ancient comet collisions…. Such ices could be valuable resources that human lunar explorers could use. And they would help answer questions about the arrival of such “volatiles” to the Earth-moon system – evidence that Earth’s geological processes have largely erased from its own surface [Christian Science Monitor]. Researchers scheduled the LRO to scrutinize the moon’s south pole in particular because of this combination of potentially useful resources and scientifically interesting sites.
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The presidential panel that recently evaluated the U.S. plan for manned spaceflight declared that “Mars is the ultimate destination for human exploration,” but stressed the financial and technical difficulties that must be overcome before a boot can be planted on that red soil. Now, the New Scientist calls attention to the greatest technical hurdle: protecting astronauts from radiation during their trips to Mars.
The radiation comes in the form of cosmic rays, which are actually speeding protons and heavier atomic nuclei that rain onto our solar system from all directions. They can slice through DNA molecules when they pass through living cells and the resulting damage can lead to cancer [New Scientist]. The residents of Earth and the temporary lodgers at the International Space Station are protected from the rays by the Earth’s magnetic field, but astronauts heading to Mars would have no natural protection. Aluminum or plastic shielding on a spacecraft would have to be impractically thick to safeguard astronauts, and other solutions, like the creation of a miniature magnetic field around the spaceship, are still being developed.
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Astronomers have conclusive evidence that a planet spotted in a star system 500 light years away is rocky and solid, just like Earth. Scientists have long figured that if life begins on a planet, it needs a solid surface to rest on, so finding one elsewhere is a big deal. “We basically live on a rock ourselves,” said co-discoverer Artie Hartzes…. “It’s as close to something like the Earth that we’ve found so far. It’s just a little too close to its sun” [AP].
Yes, for while the exoplanet, Corot-7b, is rocky like Earth and is only about five times more massive than our home planet, it’s hardly our twin. Its close proximity to its star means that it completes an orbit (its “year”) in just 20 hours, and the climate extremes are punishing. Temperatures soar above 2,000 degrees on its day side and sink to minus 200 degrees on the night side. It means the surface could be covered with molten lava or boiling oceans and it certainly could not hold any form of life as we know it [Scientific American].
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The mighty planet Jupiter has 63 official moons, but it turns out there’s always room for more. Researchers used computer models to map the past trajectory of the comet 147P/Kushida-Muramatsu, and determined that for about 12 years it circled Jupiter as a temporary moon. At the ongoing European Planetary Science Congress, astronomers declared that the comet completed two complete orbits of the gas giant, and remained in orbit from 1949 to 1961.
The 1,300-foot-wide comet had a happier fate than other comets that got too close to Jupiter, and were dragged all the way in for a crash landing. Only one temporary satellite has been observed falling prey to a planet’s pull: comet Shoemaker-Levy 9, which broke apart and crashed into Jupiter in 1994…. Unlike [Shoemaker-Levy], comet Kushida-Muramatsu eventually escaped Jupiter’s gravity. It currently circles the sun in the solar system’s asteroid belt, between the orbits of Mars and Jupiter [National Geographic News].
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The Northrop Grumman Lunar Landing Contest, a competition designed to get private space companies more involved in helping replace NASA’s aging fleet, just began its second phase on Saturday with three teams vying for a $1 million prize.
Scorpius, a 1,900-pound, rocket-powered craft, built by Armadillo Aerospace, ascended 50 meters (164 feet) into the air, flew over to land on a simulated rocky lunar surface 50 meters (164 feet) away, and then rose and flew back to land where it started. The flight included a requirement of at least 180 seconds of flying time [SPACE.com].
The successful landing puts Armadillo in a comfortable position as it waits to see if the other teams can complete the takeoffs and landings. If they can’t, Armadillo will walk home with the cash. The team also won the $350,000 phase 1 competition, a similar mock landing that only required 90 seconds of flight time.
The competition is part of the X Prize Foundation, which funds projects that benefit humanity and has already forked over $10 million to achieve a privately funded manned spaceflight. Peter Diamandis, founder and chairman of the foundation, called Saturday’s flight “a stepping stone toward suborbital tourism, rocket racing and landing on the moon” [Dallas Observer]. The two other teams are scheduled to attempt the phase 2 landing in October.
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Image: Armadillo Aerospace
In an experiment that might be classified more as a cool party trick than a scientific breakthrough, researchers levitated a mouse using a powerful superconducting magnet. Other scientists have previously levitated frogs and bugs using the same technique, but the floating mouse was the first mammal to have the honor. The trick works because the magnet generates a strong magnetic field, and because the water in the mouse’s body is weakly diamagnetic–it generates a magnetic field of its own that pushes back against the external field. Since the researchers had a strong enough magnet, the repulsive force generated by the water in each mouse cell combined to make its whole body float.
The researchers used a tiny three-week-old mouse that was only as heavy as a stack of four pennies. When the scientists levitated the youngster it appeared agitated and disoriented, seemingly trying to hold on to something. “It actually kicked around and started to spin, and without friction, it could spin faster and faster, and we think that made it even more disoriented,” said researcher Yuanming Liu…. They decided to mildly sedate the next mouse they levitated, which seemed content with floating [LiveScience].
The technique will be a boon for space research, the scientists say. “We’re trying to see what kind of physiological impact is due to prolonged microgravity, and also what kind of countermeasures might work against it for astronauts,” Liu said. “If we can contribute to the future human exploration of space, that would be very exciting” [LiveScience].
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Image: Da-Ming Zhu et al.
After months of meetings, the panel of space experts appointed by President Obama to evaluate NASA’s manned spaceflight program has returned with a dire assessment: lack of financing has put the program on an “unsustainable trajectory.” The executive summary (pdf) of the report, released yesterday, puts forth a number of ideas for how the space agency can live within its means, but the final decisions on whether to act on the ideas rests with President Obama and Congress.
Among other recommendations, the panel suggested that NASA shelve its goal of rapidly returning to the moon and instead focus on nurturing a robust commercial space industry that can handle short-term objectives of the nation’s space program, such as ferrying cargo and crew to the international space station [The Wall Street Journal]. By canceling a return to the moon (which had been scheduled for around 2020) and outsourcing routine resupply missions, the panel suggested that NASA would be able to work towards more ambitious, deep space missions like a trip to an asteroid or an expedition to Mars.
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