When NASA’s Messenger space probe swung past Mercury on September 29, it snapped this picture of the innermost planet’s barren and strange landscape. The $446 million probe’s third flyby brought it within 142 miles (228 km) of Mercury’s surface to cover more uncharted terrain, leaving 98 percent of the planet now mapped [SPACE.com].
The images taken and the data recorded during the flyby are the last that will be acquired until Messenger finally slips into orbit around Mercury in 2011. The probe has now completed about three-quarters of its swooping 4.9-billion-mile journey that will eventually bring it into orbit.
Researcher Brett Denevi explains that this enhanced color shot shows a bright area surrounding an irregular depression, with steep sides and an odd shape, “all of which are hallmarks of something like a volcanic vent,” Denevi said [SPACE.com]. The double-ring basin in the center of the photo measures about 180 miles in diameter. It appears to be a relatively young impact crater–researchers believe it formed about 1 billion years ago–and the smooth stuff on the crater floor may be even younger volcanic material.
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Image: NASA
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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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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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 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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Engines powered by chemical fuel? How passé. For the spacecraft with truly modern flair, an ion thruster is the only way to go. Such a system might not provide powerful and dramatic bursts of speed, but space agencies around the world are recognizing the benefits of its slow-and-steady approach, which is just what’s needed for cruising between planets.
Ion propulsion works by electrically charging, or ionizing, a gas and accelerating the resulting ions to propel a spacecraft. The concept was conceived more than 50 years ago, and the first spacecraft to use the technology was Deep Space 1 in 1998. Since then … there have only been a few other noncommercial spacecrafts that have used ion propulsion [Technology Review]. However, the technology has a clear advantage over chemical propulsion when it comes to long distance missions, because a very small amount of gas can carry a spacecraft a long way. Astronautics expert Alexander Bruccoleri explains that with chemical propulsion, “You are limited in what you can bring to space because you have to carry a rocket that is mostly fuel” [Technology Review].
Now, a European Space Agency (ESA) probe will use four ion thrusters to scoot all the way to Mercury, the planet nearest to the sun. That mission won’t launch until 2014, but ESA officials say the $37 million propulsion system will be the most efficient yet, and will also be the most ambitious test of the technology to date. The Mercury probe will be launched by a conventional rocket, and will continue to use chemical propulsion until it’s out of Earth orbit. When it begins its six-year cruise to Mercury, though, its ion thrusters will kick in. The system will draw electricity from solar panels; as the xenon ions pass through the electrified grids they accelerate to up to 50km a second (31 miles per second) and shoot from the rear in a parallel beam. On Earth, at sea level, the thrust would be just enough to lift a pound coin. In space, however, the same thrust will create a much much bigger lift [Telegraph].
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Scientists have spied a new exoplanet–and not only is it the biggest one yet, but it’s also moving the wrong direction. Unlike other planets, which orbit the same way their stars rotate, WASP-17 moves the opposite way, according to a study published in Astrophysical Journal.
Planets are born from the same ball of rotating gas that creates their parent star, which is why they usually orbit — and spin — in the same direction as their star. While WASP-17 is the first planet known to orbit backwards, some planets in our own solar system, such as Venus, are spinning backwards [Wired]. WASP-17’s backwards motion is known by astronomers as a retrograde orbit.
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Space aficionados are getting ready for the Perseid meteor shower, a show of shooting stars that occurs each year in the middle of August. This year, the event is expected to produce more shooting stars than usual; however, they may be slightly harder to see because of the moon’s unusual brightness due to the phase it will be in during the showers.
The Perseid Meteor Shower, which consists of debris from the Swift-Tuttle comet, became active on July 17, but have largely been so disperse and faint to see. [A] noticeable upswing in Perseid activity traditionally begins during the second week of August, leading up to their peak. They are typically fast, bright and occasionally leave persistent trains. And every once in a while, a Perseid fireball will blaze forth, bright enough to be quite spectacular and more than capable to attract attention even in bright moonlight [Space.com]. Like other meteor showers, Perseid’s fiery show is the result of particles disintegrating as they speed into the Earth’s atmosphere.
In other years, stargazers have been able to see up to 200 meteors per hour. But because the moon will be at last quarter the night of Aug. 13 and it will be at a rather bright waning gibbous phase a night or two earlier, seriously hampering observation of the peak of the Perseids, predicted to occur late on the nights of Aug. 11 and 12. [Space.com]. Still, although the moon’s brightness could hamper visibility, astronomers say the meteor shower should still be exciting to watch.
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NASA’s Kepler spacecraft has only been in operation for 10 days, but it’s already spotted a planet, according to a report in Science. That leaves experts optimistic about the craft’s potential to find other Earth-like planets.
Scientists already knew that the planet Kepler found existed. It’s called HAT-P-7b, and it’s a planetary body that’s too heavy and too hot to support life. Still, Kepler gave scientists new details about the planet, including that the planet has a hazy, ozone-like atmosphere. The analysis proves that Kepler’s onboard telescope and light-detecting instruments are at least 100 times more precise than the ground-based detectors that originally found HAT-P-7b [L.A. Times], because Earth-based telescopes must wrestle with distortion from the atmosphere, while Kepler only looks through the clear near-vacuum of space.
Scientists say that Kepler’s capabilities should be sufficient to find Earth-like planets in the “habitable zone” of a star system–that is, the ring where temperatures climb high enough to allow liquid water to exist, but aren’t so scorching as to burn up the surface of the planet.
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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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A comet from the deep space far beyond Pluto probably won’t smash into the Earth and obliterate all life, reassuring researchers said today. New calculations have determined that most extinction events that have occurred over our planet’s history probably weren’t caused by killer comet showers, which bodes well for the future, too. The findings are both welcome and well-timed since only last week an object dramatically smashed into Jupiter; many researchers believe the culprit was a comet.
In the new study, published in Science, researchers focused on long-period comets, which are among the wild cards in a thick deck of cosmic threats. In contrast with short-period comets, such as Comet Halley and Comet Tempel-Tuttle, long-period comets trace insanely eccentric orbits that range out beyond Neptune, Pluto and the Kuiper Belt to a little-understood region on the solar system’s edge known as the Oort Cloud [MSNBC]. The Oort cloud, which contains billions of small, icy objects, may extend from about 93 billion miles from the sun to as far as 9 trillion miles away.
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What lies beneath the icy crust of Enceladus? Ever since the NASA space probe Cassini snapped pictures of the Saturnian moon expelling enormous jets of icy vapor from fissures near its south pole in 2005, planetary scientists have debated whether the evidence points to liquid oceans beneath the moon’s surface. Now, a new chemical analysis of the plume bolsters the oceanic theory, thanks to the detection of a mundane chemical: ammonia. Says study coauthor Jonathan Lunine: “This is the first time Cassini has actually been able to ’smell’ ammonia…. And because ammonia is an antifreeze, it probably ensures that there is liquid water in the interior of Enceladus.” And where there’s water, there could be life [Wired.com].
Last month, another team of researchers also argued for the presence of an ocean when they published their discovery of sodium salts in Saturn’s outer-most ring which is thought to originate from Enceladus’ plume material. “The two studies are complimentary and now, for the first time, we are getting an idea of the full picture of what’s happening on Enceladus,” [Chemistry World], says Frank Postberg, lead author of that earlier study. However, Postberg’s study was contested by another paper that found no traces of sodium vapor around Enceladus, leaving the debate unresolved. Sodium is thought to be an indicator of liquid water because it suggests that salt leached from rocks into the water.
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Jupiter is sporting a new, Earth-sized scar near its south pole, and NASA has confirmed that the gas giant was thumped by a massive impact over the past few days. The discovery was made Sunday night by a Australian computer programmer who uses his spare time to stargaze with his backyard telescope, and today NASA declared that the dark spot is definitely not a weather system, and is indeed evidence of a collision. It’s not yet known exactly what smacked into Jupiter; astronomers say it could have been an unknown comet, or a stray piece of ice.
This is only the second time such an impact has been observed. The first was almost exactly 15 years ago, when more than 20 fragments of comet Shoemaker-Levy 9 collided with the gas giant. “This has all the hallmarks of an impact event, very similar to Shoemaker-Levy 9,” said Leigh Fletcher, an astronomer at NASA’s Jet Propulsion Lab…. “We’re all extremely excited” [New Scientist].
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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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