Posted on 12/14/2006 12:50:32 PM PST by NormsRevenge
SAN FRANCISCO - Detailed observations from the first comet samples returned to Earth are debunking some of science's long-held beliefs on how the icy, celestial bodies form.
Scientists expected the minute grains retrieved from a comet Wild 2 to be made up mostly of interstellar dust tiny particles that flow through the solar system thought to be from ancient stars that exploded and died.
Instead, they found an unusual mix of primordial material as if the solar system had turned itself inside out. Hot particles from the inner solar system migrated out to the cold, outer fringes beyond Pluto where they intermingled and congealed to form a comet.
"People imagine that comets form in total isolation, which is definitely not true," said Don Brownlee, a University of Washington astronomer who is the principal scientist for the $212 million Stardust mission.
Brownlee estimated that up to 10 percent of materials in comets may come from the inner solar system.
A series of papers detailing the first scientific results from the Stardust mission were to be published Friday in the journal Science and presented at an American Geophysical Union meeting Thursday.
A capsule carrying thousands of minuscule samples from comet Wild 2 returned to Earth last January after looping around the sun to capture the interstellar and comet debris and swooping past Wild 2 to scoop up dust.
Scientists had dubbed Wild 2 a frozen time capsule because it contained material preserved from the aftermath of the solar system's birth more than 4.5 billion years ago.
How material from the inner solar system could have ended up in comets is still a mystery. Brownlee said the solar system-forming process was probably chaotic and unstable, allowing high-temperature particles to loft billions of miles out to the edge of the solar system.
Many of the grains contained high-temperature minerals that likely formed in the hottest part of the solar nebula. At least one grain was made of a rare mineral seen in some meteorites, which are among the oldest samples in the solar system.
An analysis also found Wild 2 appeared to differ from comet Tempel 1, which was studied in NASA's Deep Impact mission. Last July, the space agency crashed a probe into Tempel 1 and studied the dust and ice spewing from its belly. It did not retrieve any samples from the surface.
In an accompanying editorial, Michael A'Hearn of the University of Maryland, who is also the Deep Impact chief scientist, said the Stardust results have gotten scientists thinking about their original views.
"Stardust has certainly brought us plenty of food for thought," A'Hearn wrote.
Scientists Dig Into Pile of Comet Dust (NASA's Stardust mission) ^
http://www.freerepublic.com/focus/f-news/1582564/posts
Wild 2 keyword
http://www.freerepublic.com/focus/keyword?k=wild2
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Deep Impact and Comet Tempel 1
Credit: NASA/JPL. Image manipulation: Carl Smith
From the first five frames of the flash
By isolating the brightest parts of the flash in each frame, colourising the results, and superimposing them in pairs, it is possible to see how the flash moved over time. The result strongly supports the pre-impact flash hypothesis of EU theorists.
It will be interesting to see how NASA explain this.
http://www.plasmacosmology.net/latest.html#
ping
Interesting read, thanks for the ping.
Nah, they are the same ones who tell us that the Universe has to be so many gazillion years old, so that we would have enough time to evolve to our present state of superior intelligence.
bfl, thanks
didn't check the links, probably some are goners:Far-out findings - new analysis suggests planets were formed from a giant mixParticularly significant was the discovery of calcium aluminium inclusions, which are amongst the oldest solids in the Solar System and are thought to have formed close to the young Sun. This discovery suggests that components of the comet came from all over the early Solar System, with some dust having formed close to the Sun and other material coming from the asteroid belt between Mars and Jupiter. Since Wild-2 originally formed in the outer Solar System, this means that some of its composite material has travelled great distances.
Imperial College
Department of Earth Science and Engineering
Thursday 14 December 2006
Did Jupiter Bully Other Planets in Sibling Rivalry?One possible explanation, discussed in Thursday's issue of the journal Nature, is that Uranus and Neptune formed much closer to the center of the action than their current positions might indicate. In this scheme, Jupiter and Saturn were bullies of a protoplanetary playground, shoving the other two future giants out of the way.
by Robert Roy Britt
8 December 1999Jupiter's Composition Throws Planet-formation Theories into DisarrayExamining four-year-old data, researchers have found significantly elevated levels of argon, krypton and xenon in Jupiter's atmosphere that may force a rethinking of theories about how the planet, and possibly the entire solar system, formed. Prevailing theories of planetary formation hold that the sun gathered itself together in the center of a pancake-shaped disk of gas and dust, then the planets begin to take shape by cleaning up the leftovers. In Jupiter's current orbit, 5 astronomical units from the sun, temperatures are too warm for the planetesimals to have trapped the noble gases. Only in the Kuiper belt -- a frigid region of the solar system more than 40 AU from the sun -- could planetesimals have trapped argon, krypton and xenon.
by Robert Roy Britt
Nov 17 1999
While lead researcher Tobias Owen does not put much stock in the idea that Jupiter might have migrated inward to its present position, other scientists on the team say the idea merits consideration. Owen expects the probes will find similarly high levels of noble gases in Saturn, Uranus and Neptune. Hints of these gases have even been found in the thick atmosphere of Venus, another planet now begging more study.Jupiter gave birth to Uranus and NeptuneNot too long ago, scientists regarded the orbits that the planets circle our Sun as being the ones they were born in. Now they are realising that this is not the case. Uranus and Neptune may have migrated outwards and Jupiter may have come in from the outer cold. Scientists have always been slightly puzzled by the positions of Uranus and Neptune because in their present locations it would have taken longer than the age of the Solar System for them to form. Scientists from Queen's University suggest that the four giant planets started out as rocky cores in the Jupiter-Saturn region, and that the cores of Uranus and Neptune were tossed out by Jupiter's and Saturn's gravity.
by Dr David Whitehouse
8 December 1999Newfound Moons Tell Secrets of Solar SystemThe fact that most of the satellites' orbits are retrograde and eccentric speaks volumes about their origins: They had to have come from elsewhere, and been captured by the planets at some point. If they formed at the same time as the planets, from the spinning nebular disk, their orbits would be nearly circular and in the same direction as the planets' rotation, like the "regular" moons... In the case of the irregular satellites, they could not have shifted from an orbit around the Sun to an orbit around one of the giant planets without slowing down -- through friction in an atmosphere, perhaps; the influence of gravity; or a collision with another object... But there are two other possibilities for capture, Dr. Nesvorny said. One is that rapid growth of the core led to a corresponding increase in gravity, enough to pull down a nearby object. The other is that captured objects were a result of a collision between two planetesimals, the force of the collision being enough to dissipate the energy of at least one of them. Either of these two theories may be a more likely explanation for the satellites of Uranus and Neptune, which formed differently from Jupiter and Saturn, without the large amounts of gas.
by Henry Fountain
August 12, 2003
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