[X] My Assistant

[Guest_paulanderson_*]

I thought the analysis results, as they come in, deserved their own thread. I'm interested in how these findings relate to the "weird crystals" found and reported on in the previous Nature article.

A couple more updates, from Space.com and MSNBC:

Stardust Mission Yields Ancient Comet Dust
http://space.com/scienceastronomy/060220_s...ust_update.html

Comet Dust Sparks Scientific Intrigue
http://www.msnbc.msn.com/id/11460590

"The early results reveal that the 4.5 billion-year-old comet contains iron, sulfides, glassy materials, olivine, and what the scientists termed potentially interesting isotopic traces. They believe that these materials were also available during the formation of other objects in our solar system.

What's even more amazing is how well the first round of analysis is matching expectations. Brownlee and other Stardust scientists are holding back their first formal reports for a scientific meeting in Texas next month — but during Monday's news conference, Brownlee said the samples studied so far contain iron sulfides and glassy material such as crystalline silicates. Those ingredients are found in meteorites as well.

Later, Brownlee told MSNBC.com that there were preliminary indications of organic compounds, based on telltale infrared readings. He cautioned that the initial indications were tentative and could still be traced to contaminants.

In the weeks and months ahead, Sandford and his team will be analyzing the types of carbon found in the samples — not only to trace the organics, but also to determine whether such compounds predated the formation of the solar system."

[edstrick]

RG Clark: "....This theory is controversial ONLY because it would raise the possibility of life on comets. ..."

Bull.

It's controversial because there is no indication from interplanetary dust studies, founded by Brownlee, and comet studies, that small cometary bodies ever heated up enough to produce meltwater, much less silicate melt. Evidence continues to accumulate that comets are underdense bodies ice that never melted and dusts that never turned to "mud", unlike what we think are middle and outer belt asteroid materials like the serpentinized carbonaceous chondrites and things like the Tagash Lake meteorite.

This is not to say that giant KBO's didn't heat, differentiate, melt ice and even melt silicates briefly. They probably did. But a near-Pluto sized KBO is a vastly larger object with vastly more mass per unit surface area than a few km to few tens of km comet nucleus.

Comets are probably dominated by the smaller KB objects, with some small fraction being collisional fragments from larger ones, and some being objects from the outer belt or from near Jupiter's orbit, but they will be a small fraction of the total.

Note that the presumed parent body of the Kreutz sungrazer comet family, which has been suspected of originally being perhaps 100 km or more across, (I don't have the number at hand), broke up into totally fragile crumbly chunks that disintegrate in space with little provocation like other comets have done. That one probably never melted, at least the pieces of it we see. Maybe there's a core somewhere along the sungrazers' orbit we haven't seen in human history.