Comet from coldest spot in solar system has material from hottest placesMarch 14, 2006Scientists analyzing recent samples of comet dust have discovered minerals that formed near the sun or other stars. That means materials from the innermost part of the solar system could have traveled to the outer reaches, where comets formed. "The interesting thing is we are finding these high-temperature minerals in materials from the coldest place in the solar system," said Donald Brownlee, a University of Washington astronomer who is principal investigator, or lead scientist, for NASA's Stardust mission. Among the finds in material brought back by Stardust is olivine, a mineral that is the primary component of the green sand found on some Hawaiian beaches. It is among the most common minerals in the universe, but finding it in comet Wild 2 could challenge a common view of how such crystalline materials form. Olivine is a compound of iron, magnesium and other elements, in which the iron-magnesium mixture ranges from being nearly all iron to nearly all magnesium. The Stardust sample is primarily magnesium. Many astronomers believe olivine crystals form from glass when it is heated close to stars, Brownlee said. One puzzle is why such crystals came from Wild 2, a comet that formed beyond the orbit of Neptune when the solar system began some 4.6 billion years ago. "It's certain such materials never formed inside this icy, cold body," Brownlee said. The comet traveled the frigid environs of deep space until 1974, when a close encounter with Jupiter brought it to the inner solar system. Besides olivine, the dust from Wild 2 also contains exotic, high-temperature minerals rich in calcium, aluminum and titanium. "I would say these materials came from the inner, warmest parts of the solar system or from hot regions around other stars," Brownlee said. "The issue of the origin of these crystalline silicates still must be resolved. With our advanced tools, we can examine the crystal structure, the trace element composition and the isotope composition, so I expect we will determine the origin and history of these materials that we recovered from Wild 2." Brownlee is among scientists presenting the first concrete findings from the Stardust sample this week at the annual Lunar and Planetary Science Conference in League City, Texas. Stardust's captured dust from comet Wild 2 in January 2004, and the sample-return capsule parachuted to the Utah desert on Jan. 15 to complete the seven-year mission. The samples from Wild 2 were taken to the National Aeronautics and Space Administration's Johnson Space Center in Houston, and from there they have been sent to about 150 scientists around the world, who are using a variety of techniques to determine the properties of the comet grains. The grains are very tiny, most much smaller than a hair's width. But there appear to be thousands of them embedded in the unique glassy substance called aerogel that was used to snare the particles propelled from the body of the comet. A grain of 10 microns - one-hundredth of a millimeter - can be sliced into hundreds of samples for scientists to study. "It's not much, but still it's so much that we're almost overwhelmed," Brownlee said, noting that his lab has only worked on two particles so far. "The first grain we worked on, we haven't even cut into the main part of the particle yet." The material, which came from the very outer edges of the solar system, has been preserved since the start of the solar system in the deep freeze of space 50 times farther away from the sun than Earth is. Brownlee believes the material will provide key information about how the solar system was formed. "A fundamental question is how much of the comet material came from outside the solar system and how much of it came from the solar nebula, from which the planets were formed," he said. "We should be able to answer that question eventually." University of Washington |
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| Related Comet Current Events and Comet News Articles Rosetta bound for outer Solar System after final Earth swingby This morning, mission controllers confirmed that ESA's comet chaser Rosetta had swung by Earth at 8:45 CET as planned, skimming past our planet to pick up a gravitational boost for an epic journey to rendezvous with comet 67P/Churyumov-Gerasimenko in 2014. ESA spacecraft may help unravel cosmic mystery When Europe's comet chaser Rosetta swings by Earth tomorrow for a critical gravity assist, tracking data will be collected to precisely measure the satellite's change in orbital energy. The results could help unravel a cosmic mystery that has stumped scientists for two decades. Follow Rosetta's final Earth boost ESA's comet chaser Rosetta will swing by Earth for the last time on 13 November to pick up energy and begin the final leg of its 10-year journey to comet 67P/Churyumov-Gerasimenko. ESA's European Space Operations Centre will host a media briefing on that day. 'Ultra-primitive' particles found in comet dust Dust samples collected by high-flying aircraft in the upper atmosphere have yielded an unexpectedly rich trove of relicts from the ancient cosmos, report scientists from the Carnegie Institution. Cassini Helps Redraw Shape of Solar System In a paper published Oct. 15 in Science, researchers from the Johns Hopkins Applied Physics Laboratory (APL) present a new view of the region of the sun's influence, or heliosphere, and the forces that shape it. Images from one of the Magnetospheric Imaging Instrument's sensors, the Ion and Neutral Camera (MIMI/INCA), on NASA's Cassini spacecraft suggest that the heliosphere may not have the comet-like shape predicted by existing models. NASA Goddard visualization team previews lunar impact At 7:30 a.m. EDT on October 9, a two-ton rocket body will slam into a crater near the moon's south pole. By studying the resulting plume of gas and dust, scientists hope this grand experiment will confirm the presence of ice in permanently shadowed craters at the lunar poles. CU-Boulder space scientists set for final spacecraft flyby of Mercury NASA's MESSENGER spacecraft, which is toting an $8.7 million University of Colorado at Boulder instrument, will make its third and final flyby of Mercury on Sept. 29 -- a clever gravity-assist maneuver that will steer it into orbit around the rocky planet beginning in March 2011. Sea level stargazing: Astronomers make key sighting with Fla. telescope This summer, University of Florida astronomers inaugurated the world's largest optical telescope on a nearly 8,000-foot mountaintop 3,480 miles away. Deep Impact and Other Spacecraft Find Clear Evidence of Water on Moon New data from the Deep Impact spacecraft and the Moon Mineralogy Mapper (M3), an instrument aboard India's recently ended Chandrayaan-1 spacecraft, provide, for the first time, clear evidence that water exists on the surface of the Moon. Key process for space outpost proved on 'vomit comet' ride Flying high over the Gulf of Mexico, researchers from NASA and Case Western Reserve University found a key to unlocking oxygen from the surface of the moon. More Comet Current Events and Comet News Articles |
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