Secondary electron image of the Coki section analyzed in this study showing mineral shards surrounded by compressed aerogel. Credit: Lawrence Livermore National Lab.

New Results from Stardust Mission Paint Chaotic Picture of Early Solar System

26 Feb , 2010 by

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One of the most surprising results from the Stardust mission – which returned comet dust samples to Earth in 2006 – is that comets don’t just consist of particles from the icy parts of the outer solar system, which was the common assumption, but also includes sooty dust from the hot, inner region close to the Sun. A new study confirms this finding, and also provides the first chronological information from the Wild 2 comet (pronounced like Vilt 2). The find paints a chaotic picture of the early solar system.

Even some of the first looks at the cometary particles returned by Stardust showed that contrary to the popular scientific notion, there was enough mixing in the early solar system to transport material from the sun’s sizzling neighborhood and deposit it in icy deep-space comets. Whether the mixing occurred as a gentle eddy in a stream or more like an artillery blast is still unknown.

“Many people imagined that comets formed in total isolation from the rest of the solar system. We have shown that’s not true,” said Donald Brownlee back in 2006, principal investigator for Stardust.

The new study, conducted by scientists from Lawrence Livermore (Calif.) National Laboratory, shows the dust from comet 81P/Wild 2 has been altered by heating and other processes, which could have only occurred if a transport of space dust took place after the solar system formed some 4.57 billion years ago.

“The mission was expected to provide a unique window into the early solar system,” the team, led by Jennifer Matzel wrote in their paper, “by returning a mix of solar system condensates, amorphous grains from the interstellar medium, and true stardust – crystalline grains originating in distant stars. Initial results, however, indicate that comet Wild 2 instead contains an abundance of high-temperature silicate and oxide minerals analogous to minerals in carbonaceous chondrites.”

Corresponding false color mineral map overlaid on a montage of brightfield Transmission Electron Microscope (TEM) images.


They analyzed a particle from the comet, about five micrometers across, known as Coki. The particle does not appear to contain any of the radiogenic isotope aluminum-26, which implies that this particle crystallized 1.7 million years after the formation of the oldest solar system solids. This means that material from the inner solar system must have traveled to the outer solar system, across a period of at least two million years.

“The inner solar system material in Wild 2 underscores the importance of radial transport of material over large distances in the early solar nebula,” said Matzel. “These findings also raise key questions regarding the timescale of the formation of comets and the relationship between Wild 2 and other primitive solar nebula objects.”

The presence of CAIs in comet Wild 2 indicates that the formation of the solar system included mixing over radial distances much greater than anyone expected.

Sources: LLNL, Astrobiology

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Jorge
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Jorge
February 26, 2010 12:35 PM

I love science. Especially when it confirms what I’ve always thought! grin

Aqua4U
Member
February 26, 2010 6:36 PM

“…but also includes sooty dust from the hot, inner region close to the Sun.”

Does ‘sooty’ mean carbon filled?

Aqua4U
Member
February 26, 2010 6:46 PM

Any shocked nano diamonds in there?

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
February 27, 2010 7:16 AM
I too feel rewarded when science tests my conception of reality. In this case I have started to suspect that, as in biology, transient processes are unnecessarily argued as sudden due to lack of (mainly) temporal resolution. This test my prediction that such man made preconceptions will fall if tested. Just the other day I gleaned another such area. A few weeks ago there was this paper that rather conclusively (in this layman’s eyes) tested that the dominant part of our volatiles must have come from such cometary material we see above, presumably at the Last Heavy Bombardment (LHB) at 4.1 to 3.8 Ga. Isotope ratios couldn’t explain the magmatic content solely by way of planetoid collision and… Read more »
Navneeth
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Navneeth
February 27, 2010 1:28 AM

Nancy, some people might not know what a CAI is unless they read the release from LLNL. smile

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
February 27, 2010 7:38 AM
It strikes me that one way that would keep the Zn world hypothesis intact is if indeed early volatile supply included at least 10 atmospheres of CO2, while the end result were way above that and something similar to Venus. There is of course no reason to think not, and every reason to think that Venus and Earth were alike each other, before plate tectonics stopped/never started on Venus for whatever reason. I think I like that. Then the above comment remains in main, and specifically the observation of the gradual processes of getting atmospheres respectively life. It is but the gradualness of the “enzymes or metabolism” paradox resolution that fails miserably – Zn world did it inherently… Read more »
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