Re: Lecture of the Week: Part V: Astrobiology
- From: "Wirt Atmar" <atmar@xxxxxxxxxxxxxxxxx>
- Date: Sun, 25 Jun 2006 17:16:28 -0400 (EDT)
Jim writes:
"Wirt Atmar" <atmar@xxxxxxxxxxxxxxxxx> wrote in message news:e7cbcg$233g$1@xxxxxxxxxxxxxxxxxxxxxx
The Evolutionary Biology Lecture of the Week for June 19, 2006 is now[snip]
available at:
http://aics-research.com/lotw/
June 19, 2006
Part V: Astrobiology
Sympathy for the Devil:
The Case for Life on Venus
David Grinspoon, Southwest Research Institute, Boulder
33 min.
Venus has not traditionally been considered a promising target for
astrobiological exploration, yet Grinspoon proposes that Venus should
be central to such an exploration program for several reasons. All of
our ideas about extraterrestrial biochemistry are, of necessity,
extrapolations from the single example of life which we have been able
to study. Planetary exploration, with an increasing focus on
astrobiology, has been designed to "follow the water." This is a
reasonable strategy but it is based, at best, on an educated guess
about life's universals.
If we think beyond the specifics of a particular chemical system
required to build complexity and heredity, we can ask what general
properties a planet must possess in order to be considered a possible
candidate for life. Grinspoon argues that the answers might include an
atmosphere with signs of chemical disequilibrium and active, internally
driven cycling of volatile elements between the surface, atmosphere and
interior, what he calls his "Living Worlds Hypothesis." At present, the
only two planets we know of which possess these characteristics are
Earth and Venus.
Thx Wirt. An interesting lecture. Grinspoon even hints that there might
be life on Venus today - in the mid-level clouds where temperatures and
pressures are more Earth-like, there may still be some water, and it appears
that the cloud droplets are not mostly H2SO4 (as they are higher up).
So what are the clouds made of at that level? We don't know, but
Grinspoon has some tantalizing suggestions.
David Grinspoon has also written a simply excellent book, "Lonely
Planets: the natural philosophy of alien life." Despite its title, it's
a perfectly serious look at the history and philosophy of the new
science of astrobiology, and I highly recommend it.
Life in the clouds of Venus is a long shot, and no one knows that
better than Grinspoon. But it's not impossible, and we can imagine its
existence at this point in time only because of our lack of knowledge.
But it's also important to remember that there was a time when
dinosaurs were given at least a chance of existing on the surface of
Venus because we knew that Venus was cloud covered and that it had to
be warm, and what other form of life should exist in such swampy
conditions other than dinosaurs?
Theory often precedes observation, but when it precedes it greatly, it
becomes unhinged from actual knowledge and lapses over into unbridled
speculation. Theory obviously has its place, but it can never supplant
just going out and taking a look and seeing what's real and what's not.
Theory almost never surprises us. In contrast, exploration almost
always does.
Wirt Atmar
.
- References:
- Lecture of the Week: Part V: Astrobiology
- From: Wirt Atmar
- Lecture of the Week: Part V: Astrobiology
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