You may remember back in October that NASA scientists downgraded the threat of the asteroid Apophis slamming into the Earth from remote to even more remote. Thanks to refined computation of the object’s motion, astronomers changed their estimate of the chances for a 2036 collision from an already unlikely 1 in 45,000 chance to a further long shot of 1 in 250,000. Well, that wasn’t enough to ease the head of Russia’s space program, Anatoly Perminov, who today said his nation would plan an ambitious space program to spare the Earth from certain doom, and would eventually ask other world powers to join Russia on this quest.
Without mentioning NASA findings, Perminov said that he heard from a scientist that Apophis is getting closer and may hit the planet. “I don’t remember exactly, but it seems to me it could hit the Earth by 2032,” Perminov said [AP]. Truly, Perminov didn’t remember exactly: Apophis makes a close but harmless pass of our planet in 2029, when it could come within 20,000 miles of Earth, and then swings by again in 2036 (the visit for which NASA downgraded the danger to the remote four-in-a-million).
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A panel evaluating NASA‘s goals has made some bold suggestions for the agency, including yearlong missions into deep space and even landing on Mars‘ moon, Phobos.
NASA’s current goal is to land humans on the moon once again by 2020, but the panel, which was set up by the White House, has suggested other possible ventures that could speed NASA towards another goal: a manned mission to Mars. For example, long missions to deep space would help scientists learn how to manage long-duration space missions far from Earth, which human missions to Mars would require…”It is true we need to gain experience exploring planetary surfaces, but in fact we’ve done some of that…. What we actually have almost no experience at all with is operations in deep space” [New Scientist], said committee member Edward Crawley. Missions into deep space would require further research into how to protect humans from space radiation, the harmful charged particles from which lower-orbit missions are shielded by the Earth’s magnetic field.
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The solar system’s main asteroid belt may have taken its shape when three gas giant planets were flung into more distant orbits, scattering the remote, icy objects that were lurking at the solar system’s edge. A new study, published in Nature, suggests that the event sent “space invaders” to the belt between Mars and Jupiter that seem more like primitive frozen comets than the baked rocks that make up the overwhelming majority of asteroids [AP].
The findings support a recent theory for the solar system’s formation called the Nice model (named after the city in France), which suggests that all four gas giants originally formed near to the sun, but migrated in what “we believe was a very violent event that happened roughly 700 million years after the solar system formed,” when the solar system was in “its teenage years,” [SPACE.com], explains study coauthor Harold Levison. He says the original orbits of the gas giants weren’t stable, and “the orbits really just went kablooy”. Jupiter moved inwards, while Saturn, Uranus and Neptune all moved away from the Solar System’s centre. As they did so, they catapulted icy bodies from the early protoplanetary disc into the inner Solar System [Nature News].
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NASA astronauts may not be assigned to a stint at a lunar base anytime soon. A statement by a NASA official suggested that the space agency is likely to scrap the idea of a permanent moon base, but could instead try to speed up other, more ambitious manned missions to explore our solar system.
NASA has been working towards returning astronauts to the moon by 2020 and building a permanent base there. But some space analysts and advocacy groups like the Planetary Society have urged the agency to cancel plans for a permanent moon base, carry out shorter moon missions instead, and focus on getting astronauts to Mars [New Scientist]. When the agency’s acting administrator, Chris Scolese, testified before a congressional subcommittee yesterday, he said that the agency probably won’t aim to build an outpost on the moon, suggesting that the agency may be following those advocates’ advice.
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The enormous meteor that smashed into Mexico’s Yucatan peninsula 65 million years ago didn’t deal a death blow to the dinosaurs, a new study declares. Based on a close examination of sediment layers from that epoch, a team of researchers led by Gerta Keller has previously argued that the Chicxulub impact happened 300,000 years before the mass extinction known as the Cretaceous-Tertiary extinction event. Now, Keller has found supporting evidence that the impact had little immediate effect on the planet’s biome. Says Keller: “It didn’t kill the dinosaurs. In fact, it didn’t cause much damage that we can determine from the geological record” [The Scientist].
Since the 112-mile-wide Chicxulub crater was discovered in 1978, many researchers have come to believe that the massive impact caused clouds of dust to shroud the earth, cooling the planet and killing the dinosaurs along with many other species. But Keller’s new study, to be published in the Journal of the Geological Society, offers a serious challenge to that theory.
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Astronomers are hoping to catch a glimpse of debris that could be leftover from a cosmic collision between our Earth and a Mars-sized planet called Theia–if, in fact, it existed at all. “It’s a hypothetical world. We’ve never actually seen it, but some researchers believe it existed 4.5 billion years ago — and that it collided with Earth to form the moon,” said Mike Kaiser, a NASA scientist [SPACE.com].
The research will be done with the two Stereo spacecraft that are on their way to observe the sun; on their way they’ll have a chance to do some “bonus science,” as one researcher called it. The spacecraft are passing through two regions of space, called Lagrangian points, where the gravity from the Earth and the sun combine to form wells that tend to collect solar system detritus…. Scientists think Theia may even have formed in one of these gravitational points of balance from the accumulation of flotsam that had built up there [SPACE.com].
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They saw it coming, and they got what was coming to them. For the first time, researchers not only detected an asteroid in space, but also tracked its progress and then collected its debris after it crashed to Earth [Science News].
Astronomers won the space lottery last October when they spotted a small, car-sized asteroid headed straight for Earth 19 hours before it reached our planet, and were able to study it as it plunged towards the atmosphere. When the rock exploded about 23 miles above the Nubian Desert in northern Sudan, many astronomers thought that was the end of an already remarkable story. But researcher Peter Jenniskens decided to see if any fragments had reached the Earth’s surface, and joined forces with a team of Sudanese scientists and students to comb the desert.
Small asteroids like 2008 TC3 are fairly common, with about one asteroid impacting Earth each year. But these small asteroids are usually not spotted until they enter the Earth’s atmosphere. “It’s like when bugs splatter on the windshield. You don’t see the bug until it’s too late,” says physicist and study coauthor Mark Boslough [Science News]. Researchers got lucky with this asteroid–it was spotted by chance by an observatory in Arizona.
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Left-handed people may be in the minority, but left-handed amino acids rule the Earth. Researchers have long known that the building blocks of proteins can be constructed in either “left-handed” or “right-handed” versions that are mirror images of each other, but that almost every living organism on Earth uses left-handed amino acids. Now, a new study gives weight to a theory of how that preference came to pass. NASA researchers examined meteorites that predate the Earth’s formation, and say that those early rocks also have a preponderance of left-handed molecules. “Meteorites would have seeded the Earth with some of the prebiotic compounds like amino acids that are needed to get life started, and also biased the origin of life to the left-handed amino acid form,” says [study coauthor] Daniel Glavin [New Scientist].
Researchers note that if you make amino acids from scratch in a lab using their chemical components, you inevitably get half of the right-handed version and half of the left handed version. So it might be expected that if nature makes amino acids in space using similar chemistry, you’d also get a fifty-fifty mixture [CBC]. Yet that’s not what Glavin and his colleagues found when they studied the molecular deposits in six meteorites that are more than 4.5 billion years old. Instead, they found the ratio of amino acids tilted toward left-handedness in all six specimens. In one of the rocks, the imbalance was 18%, the largest ever reported for a meteorite. “I have to admit I didn’t believe it at first,” Glavin says [ScienceNOW Daily News].
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The distinctive belt of asteroids between Mars and Jupiter may have been shaped during a game of planetary pinball almost 4 billion years ago. A new study suggests that the migration of the mighty gas giant planets tugged some asteroids into a ringed formation, and sent others spinning off. Jupiter, Saturn, Uranus, and Neptune, are thought to have been born close together before gravitational interactions with numerous pieces of rocky debris changed their trajectories. Their movement then caused the rocky debris to scatter like bowling pins, potentially explaining what battered the Earth, Moon, and Mars with so many craters some 3.8 billion years ago [New Scientist].
Astronomers have long wondered about the uneven distribution of debris within the asteroid belt, which has zones where there are far fewer asteroids than expected…. Some of those gaps, called Kirkwood gaps, are in zones where Jupiter or Saturn’s gravitational influence destabilises the asteroids so much that they are ejected from the belt, but many are in areas that are currently stable [Cosmos]. Researchers decided to test the theory that planetary migrations caused the gaps in the solar system‘s early days.
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Around 3.9 billion years ago a massive asteroid may have slammed into the moon with such force that it changed the satellite’s rotation, according to a new analysis by a pair of astrophysicists. The impact may have set the moon to spinning, so that it eventually settled down with a 180 rotation from its previous orientation. Currently, earthlings looking up at the moon always see its same side; the other “dark side” of the moon is pointed away as a result of synchronous rotation, a sort of orbital lockstep that keeps the moon rotating once for every lap it takes around Earth [Scientific American]. The new findings suggest that Earth had a different view of the moon 3.9 billion years ago, although there was probably no life on the planet to take notice.
The researchers came to this surprising conclusion by analyzing the moon’s craters. According to earlier computer simulations, the moon’s western hemisphere as viewed from Earth should have about 30 per cent more craters than the eastern hemisphere. That’s because the west always faces in the direction in which the moon orbits, which makes it more likely to be hit by debris, for the same reason that more raindrops strike a moving car’s front windshield than its rear [New Scientist]. When researchers examined the age of the craters, however, they found a more complex scenario. The western hemisphere did have the greatest concentration of young impact basins, but the eastern hemisphere had most of the old craters. This suggests that the eastern hemisphere was once positioned to receive a heavy bombardment, and that the moon once had a different orientation.
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A tiny moon rock only two inches across that was picked up by one of the last astronauts to walk on the moon has given researchers new insight into the geological history of Earth’s satellite. The rock, scooped up during the Apollo 17 mission in 1972, is about 4.2 billion years old, and shows evidence that the moon once had a molten iron core that generated a magnetic field in the satellite’s early days. The findings are forcing researchers to rethink the prevailing notion that objects smaller than Mars can’t maintain a stable magnetic field.
Many of the rocks brought back from the Moon have a faint magnetic signal, suggesting that they originally cooled from magma when the Moon had a magnetic field. That was a surprise to many scientists who thought the Moon was too small and too cold to have ever possessed a geomagnetic dynamo where electric currents from the convection of molten iron generate a field [The New York Times]. But a molten core wasn’t the only explanation for the magnetic traces; some researchers thought that an intense bombardment of meteorites and asteroids created shocks that magnetized the rocks.
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Dead stars surrounded by fields of dust from pulverized asteroids may seem to make up a forbidding and ominous picture, but researchers who studied six such star systems say the dust should actually fuel the optimism of people who dream of finding extraterrestrial life. The dust’s composition suggests that rocky planets like our own Earth may be common in the universe, researchers say, which ups the chance that life as we know it has evolved somewhere out there.
The dust in question was found surrounding small, dense white dwarf stars. As stars like our own sun near the end of their life, they puff up into red giants that consume their innermost planets and jostle the orbits of outer planets and asteroids. Eventually the stars blow off their outer layers and shrink down into white dwarfs. Occasionally, a perturbed asteroid will wander too close to the white dwarf, whose gravity rips the rocky body to shreds, forming debris [SPACE.com].
That debris is what researchers studied with NASA’s Spitzer Space Telescope. By viewing the stars through a spectrograph, which separates out light from different wavelengths, the scientists were able to observe the telltale signatures of certain chemicals in the light. Since that starlight is passing through the film of the asteroid debris, the light picked up signatures of the asteroids’ composition, too [Wired News]. Lead researcher Michael Jura announced at the ongoing American Astronomical Society meeting that the composition of the asteroid dust was remarkably similar to that of the rocky planets in our solar system.
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An asteroid that crashed into the earth 65 million years ago may not have been the cause of the dinosaurs‘ extinction, a group of researchers are arguing. Instead, that impact may have been just a prelude to the main event, when a wave of volcanic eruptions spewed out massive clouds of sulfur dioxide, clouding the air and bringing showers of acid rain. The researchers are basing their theory on studies of an area in India called the Deccan Traps, which was convulsed with volcanic activity around 65 million years ago. At least four waves of massive eruptions spread successive sheets of thick basalt across the land for more than 500 miles, and they piled into a plateau more than 11,000 feet high over thousands of years [San Francisco Chronicle].
The new research on the Deccan Traps volcanoes, announced at the ongoing meeting of the American Geophysical Union, are the first major challenge to the asteroid theory that has dominated dinosaur extinction studies for three decades. That theory posits that a six-mile-wide asteroid slammed into Mexico’s Yucatan peninsula, creating the Chicxulub crater and cooling the climate so drastically that the majority of life forms went extinct in what’s known as the Cretaceous-Tertiary (or K-T) extinction. But geologist Gerta Keller and her colleagues argue that the impact occurred well before the massive die-offs began. By examining sediment layers, the team found that the crater impact appears to have occurred about 300,000 years before the K-T boundary, with virtually no effects to biota. “There is essentially no extinction associated with the impact,” Keller said [LiveScience].
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The nearest planetary system to our own has two asteroid belts in addition to a previously known ice belt, according to the latest observations by NASA’s Spitzer Space Telescope. The location and structure of the asteroid belts relative to the system’s central star, Epsilon Eridani, suggests the existence of earth-like planets. “We certainly haven’t seen it yet, but if its solar system is anything like ours, then there should be planets like ours,” says astronomer Massimo Marengo of the Harvard-Smithsonian Center for Astrophysics [USA Today].
The Epsilon Edidani system has long been of interest to astronomers and science fiction fans alike because of its proximity (10.5 light-years) and resemblance to our solar system. The newly discovered asteroid belts give the system an appearance even more like our own. The inner asteroid belt looks identical to ours in terms of material, and it orbits at 3 astronomical units (AU) from Epsilon Eridani — the same distance between the sun and the rocky asteroid belt between Mars and Jupiter. (An astronomical unit equals the average Earth-sun distance of 93 million miles, or about 150 million km.) Epsilon Eridani’s second asteroid belt is 20 AU from the star, or about where Uranus is in relation to our sun, and it is crowded with as much mass as Earth’s moon [Science News]. The outer asteroid belt was captured directly by Spitzer’s infrared cameras and the inner asteriod belt, though too far from the cameras, was indicated by the thermal energy from its infrared emissions.
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Yesterday, astronomers had the thrill of detecting an asteroid headed straight for earth and watching it hit our planet’s atmosphere just when they predicted, but without any of the panic that might be expected to accompany the foreknowledge of an asteroid strike. The space rock, which was about nine feet in diameter, was too small to do any damage, and burned up in the atmosphere while astronomers watched.
The object’s entry into the atmosphere wasn’t that unusual: Such an event happens roughly every three months. But this is “the first time we were able to discover and predict an impact before the event”, says Donald Yeomans, manager of NASA’s Near-Earth Object (NEO) programme [Nature News]. Researchers say the accurate prediction bodes well for humanity, for it suggests that astronomers are up to the challenge of detecting and tracking larger asteroids that could pose a more serious threat to human populations. Says Yeomans: “There are still a few kinks, a few processes that need to be smoother. But we passed this test” [Nature News].
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