Exobiology in the Solar System & The Search for Life on Mars - ESA

I.7 Summary of <strong>the</strong> Science Team
Recommendations
MARS is <strong>the</strong> prime target. <strong>The</strong> search <strong>for</strong> life on Mars is presented <strong>in</strong> Part II of this
volume.
EUROPA and o<strong>the</strong>r bodies possibly hav<strong>in</strong>g subsurface water, with <strong>the</strong> accompany<strong>in</strong>g
<strong>in</strong>ternal heat sources, are also candidates <strong>for</strong> both extant and ext<strong>in</strong>ct life
searches <strong>in</strong> <strong>the</strong> future. NASA has an outl<strong>in</strong>e plan <strong>for</strong> a Europa Orbiter mission
<strong>in</strong> 2004 and a Lander <strong>in</strong> 2011.
TITAN has an atmosphere of nitrogen (90%) and methane, toge<strong>the</strong>r with a great
number of trace hydrocarbons, nitriles and oxygen compounds (CO, CO 2).
Surface deposits of hydrocarbons have been predicted, although water ice is
now considered to be dom<strong>in</strong>ant. Interest lies <strong>in</strong> <strong>the</strong> study of fundamental
physical and chemical <strong>in</strong>teractions driv<strong>in</strong>g a planetary organic chemistry and <strong>in</strong>
<strong>the</strong> possible development of a life system <strong>in</strong> <strong>the</strong> absence of liquid water but with
o<strong>the</strong>r liquids. <strong>The</strong> NASA/ESA Cass<strong>in</strong>i/Huygens mission will deliver an
atmosphere/surface probe to Titan <strong>in</strong> 2004. A NASA Titan Aerobot mission is
<strong>in</strong>dicated <strong>for</strong> 2013.
METEORITES provide a sample of various types of solar ‘debris’ and a sample of
<strong>the</strong> material ejected from o<strong>the</strong>r <strong>Solar</strong> <strong>System</strong> bodies – Mars and <strong>the</strong> Moon be<strong>in</strong>g
<strong>the</strong> sources of a small number of meteorites of identified orig<strong>in</strong>. <strong>The</strong> Mars
meteorites are be<strong>in</strong>g closely studied <strong>for</strong> evidence of ext<strong>in</strong>ct life. Ef<strong>for</strong>ts should
be made to reduce <strong>the</strong> bias of <strong>the</strong> meteorite-collection process <strong>in</strong> <strong>the</strong> field, which
tends to favour <strong>the</strong> more readily dist<strong>in</strong>guishable meteorites of igneous orig<strong>in</strong>.
<strong>The</strong> acquisition of a sample derived from martian sedimentary material would
be a major breakthrough and one that would likely yield important <strong>in</strong><strong>for</strong>mation
concern<strong>in</strong>g <strong>the</strong> possibility of life on Mars as well as <strong>the</strong> associated geochemistry.
COMETS were probably an important source of organics <strong>for</strong> <strong>the</strong> primitive Earth and
o<strong>the</strong>r planetary bodies at that early epoch. Hence ESA’s Rosetta mission,
<strong>in</strong>clud<strong>in</strong>g a lander, to Comet Wirtanen, launched <strong>in</strong> 2003 and culm<strong>in</strong>at<strong>in</strong>g <strong>in</strong>
2013. Rosetta will be a major step <strong>for</strong>ward <strong>in</strong> determ<strong>in</strong><strong>in</strong>g <strong>the</strong> full nature of <strong>the</strong>
range of cometary materials and establish<strong>in</strong>g <strong>the</strong>ir likely role as precursors of
life.
METEORITES and MICROMETEORITES have also been responsible <strong>for</strong> <strong>the</strong> import
of major amounts of extraterrestrial organic material to <strong>the</strong> Earth. It has been
estimated that <strong>the</strong>y may have brought <strong>in</strong> about 10 20 g of carbon over <strong>the</strong> 300
million years of <strong>the</strong> late bombardment phase. This exceeds <strong>the</strong> carbon conta<strong>in</strong>ed
<strong>in</strong> <strong>the</strong> current biomass (10 18 g). Cont<strong>in</strong>u<strong>in</strong>g studies on <strong>the</strong> organic components of
<strong>the</strong> carbonaceous chondrites and improved collection of micrometeorites to
allow unambiguous analysis of <strong>the</strong> organic components are needed. <strong>The</strong> latter
will <strong>in</strong>volve <strong>the</strong> fur<strong>the</strong>r development of <strong>in</strong>-orbit collection techniques to be used
on <strong>the</strong> International Space Station and o<strong>the</strong>r vehicles.
I.7.1 <strong>The</strong> <strong>Search</strong> <strong>for</strong> Extant
and Ext<strong>in</strong>ct <strong>Life</strong>
I.7.2 <strong>The</strong> Study of <strong>the</strong>
Precursors of <strong>Life</strong>
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