Analysis of Stardust materials reveals similarity to asteroids

Getting into the details: Stardust impact tracks and light gas gun impacts of sulfide in aerogel both display metal beads with sulfide rims indicating that GEMS-like objects in Stardust are generated by impact mixing of comet dust with silica aerogel. (left) Stardust GEMS-like material and (right) light gas gun shot GEM-like material. GEMS in cometary IDPs do not contain sulfide-rimmed metal inclusions. [Image credit: Hope Ishii, LLNL]


Stardust impact tracks created by comet dust entering silica aerogel at 6 km/s. [Image credit: NASA/JPL]

From the article...

Contrary to expectations for a small icy body, much of the comet dust returned by the Stardust mission formed very close to the young sun and was altered from the solar system’s early materials.

When the Stardust mission returned to Earth with samples from the comet Wild 2 in 2006, scientists knew the material would provide new clues about the formation of our solar system, but they didn’t know exactly how.

New research by scientists at Lawrence Livermore National Laboratory and collaborators reveals that, in addition to containing material that formed very close to the young sun, the dust from Wild 2 also is missing ingredients that would be expected in comet dust. Surprisingly, the Wild 2 comet sample better resembles a meteorite from the asteroid belt rather than an ancient, unaltered comet.

Comets are expected to contain large amounts of the most primitive material in the solar system, a treasure trove of stardust from other stars and other ancient materials. But in the case of Wild 2, that simply is not the case.

By comparing the Stardust samples to cometary interplanetary dust particles (CP IDPs), the team found that two silicate materials normally found in cometary IDPs, together with other primitive materials including presolar stardust grains from other stars, have not been found in the abundances that might be expected in a Kuiper Belt comet like Wild 2. The high-speed capture of the Stardust particles may be partly responsible; but extra refractory components that formed in the inner solar nebula within a few astronomical units of the sun, indicate that the Stardust material resembles chondritic meteorites from the asteroid belt.

Link: LLNL Press Release

Link: New Scientist Article