[extropy-chat] Scientists Confront 'Weird Life' on Other Worlds

[Amara Graps]

Mike Lorrey <mlorrey at yahoo.com>:
>All this being said, it's evident that unless a planet were liquid rock
>at its surface, any exceedingly unlikely Si based life forms would


You can bring silicates up to the surface by volcanism.

Examples

Earth volcanism
The more viscous the magma, the more explosive the eruption
because the gases cannot escape as easily and pressure builds. An
explosive eruption (from a high viscosity magma) can occur from
either having a higher SiO2 content in the magma, or having a
cooler temperature in the magma.


Io volcanism
http://volcano.und.nodak.edu/vwdocs/planet_volcano/Io/svs.html

"High resolution images of hot spots using Galileo's CCD system
are interpreted to be caldera floors (actively convecting lava
lakes) and/or possibly pahoehoe lava flows. The small areas are
thought to have temperatures of at least 725 degrees Celsius or
higher (Note: these temperatures are higher than the boiling
point of sulfur in a vacuum). These images are some of the best
evidence for active silicate volcanism (possibly basalt) on Io."

http://www.planetaryexploration.net/jupiter/io/volcanism_on_io.html

"The global extent of sulfur on Io caused considerable debate as
to whether Io's volcanic features were produced by molten rock
(silicate volcanism) or molten sulfur. The arguments favoring
silicate volcanism were supported by the fact that the tall
mountains and deep, steep-sided calderas on Io require a material
of considerable strength to support them. The issue was finally
resolved when Earth-based telescope detected temperatures at hot
spots ranging from 1000 K to 1800 K. This is far too hot for
sulfur to remain liquid, so silicate magma has to be involved in
these high temperature eruptions. But that does not rule out the
possibility that some of the lava flows on Io are composed
primarily of sulfur. In fact, the distribution of sulfur on Io is
still a subject of some debate. It may be that sulfur constitutes
a relatively thin coating on Io's surface, or it could form
relatively thick deposits in localized areas."


Amara

-- 

********************************************************************
Amara Graps, PhD          email: amara at amara.com
Computational Physics     vita:  ftp://ftp.amara.com/pub/resume.txt
Multiplex Answers         URL:   http://www.amara.com/
********************************************************************
"Dare to be naive." -- Buckminster Fuller