Space Forum / SETI / February 2006

NASA Postpones Stardust Mission Media Update.
"NASA has postponed the Stardust comet mission media briefing scheduled
for 1 p.m. EST (12 p.m. CST), Tuesday. The agency plans to allow the
Stardust science team additional time to assess and distribute cometary
samples before scheduling media briefings.
"NASA has enlisted more than 150 experts to accelerate sample studies.
The first samples will be shipped to researchers this week."
http://www.spaceref.com/news/viewpr.html?pid=18821

Will there be found "tar" in the particles? The interstellar dust
collector on Stardust had already found complex organic tar-like
molecules with its CIDA mass spectrometer:

Tarlike macro-molecules detected in 'stardust'
MAX-PLANCK INSTITUTE NEWS RELEASE
Posted: April 29, 2000
"It is the size of these molecular fragments with nuclear masses of up
to 2000 (water e.g. has 18 such units) which surprised us as much as
the seemingly absence of any mineral constituents", explains Dr. Kissel
of the Garching-based Max-Planck-Institut für extraterrestrische
Physik. "Only organic molecules can reach those sizes". The largest
molecules found in space so far are the polycyclic aromatic
hydrocarbons (PAH) which reach masses of a few hundred mass units.
"The details of the mass spectra measured with CIDA show that the
molecules of the interstellar dust must have about 10 percent of
nitrogen and/or oxygen in addition to hydrogen and carbon. This means
that these cannot be pure PAHs, which are planar, but are especially
due to the nitrogen extend into all three spacial directions."
http://www.spaceflightnow.com/news/n0004/29tarstardust/

These "tar-like" particles were presumed to be interstellar because of
their direction and high-speed. However, it is notable that the Giotto
spacecraft also detected "tar-like" materials on the surface of comet
Halley. Perhaps these detected particles arose from comets in other
systems. Another possibility is that the CIDA mass spectrometer
detected particles that arose from jets from comets in our system. That
could explain their high speeds and unexpected directions.
On Earth, actual tar is formed in nature from combustion or decay of
living material:

Tar
http://en.wikipedia.org/wiki/Tar

La Brea Tar Pits.
http://en.wikipedia.org/wiki/La_Brea_Tar_Pits

Even when produced in industry you still need petroleum products or
coal derivatives to produce it, which themselves arise from prior
living material.
If the returned Stardust grains are found to contain true tar that
would suggest they arose from past life in space.

c.f.,

Newsgroups: sci.astro, sci.astro.seti, rec.arts.sf.science,
sci.bio.misc
From: Robert Clark <rgcl>
Date: 2000/04/29
Subject: Re: Tarlike macro-molecules detected in 'stardust' (Forwarded)

http://groups.google.com/group/sci.astro.seti/msg/f42528d44bba448a

    Bob Clark