From: Jeff Davis (jrd1415@yahoo.com)
Date: Fri Dec 20 2002 - 02:52:56 MST
First, thanks Reason, for your response.
40-100 solar masses(maybe as high as 1000 Msol);
stellar lifetime less than 1 million years.
------------------------
Now, take note of this paper--oddly short--which
suggests an alternate ***and ubiquitous*** method of
dispersal to either impact ejecta, or deliberate
interstellar seeding (Crick's directed panspermia).
Panspermia revisited
http://xxx.lanl.gov/PS_cache/astro-ph/pdf/9909/9909013.pdf
"The solution is to argue that suitably shielded
microorganisms can be ejected from a planetary system
like ours when the star is in its red giant stage."
But he doesn't elaborate further?!!!
He also writes:
"...even if the biological material is damaged on its
journey,...,even the arrival of fragments of DNA and
RNA on Earth some 4000 million years ago would have
given a kickstart to the processes by which life
originated here."
It seems that as one looks more closely at the
panspermia concept it undergoes a natural evolution.
It starts out with the idea of whole spores able to
revive and then reproduce in an appropriately resource
rich environment. Then stripped to the essentials, it
becomes the delivery of a/the crucial prebiological
fragment that surmounts a crucial prebiological
developmental-sequence bottleneck.(As Robert
suggests.)
Logically such a fragment would be more durable than
an entire organism--bacterial spore, etc--affording it
more travel time before being trashed.
Regarding Gene's point about the low transit speeds
with the long radiation exposures: If a biological
fragment exits the local gravity well with a
tangential velocity low relative to the velocity
necessary for a relatively circular orbit of the
galactic center, won't it simply accelerate inward and
'across the galaxy' in a severe elliptical orbit like
a comet around the sun? If--as seems somewhat
reasonable to me at first glance--the orbit precesses
at all, might not such an orbit take the fragment to
any quadrant of the galaxy interior to the radial
distance of the point of origin?
Once again let me wish you all a safe and happy
holiday season. Drive carefully.
Best, Jeff Davis
"We're a band of higher primates stuck on the surface
of an atmosphere-hazed dirtball. I can associate with
that. I certainly can't identify with which patch of
the dirtball I currently happen to be on, and which
monkey tribe happens to reside therein.
Only by taking the big view we can make it a common
dream, and then a reality. It's worth it."
Eugen Leitl
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