[meteorite-list] Lichen Survives in Space

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Nov 8 16:11:16 2005
Message-ID: <200511082109.jA8L9XC12058_at_zagami.jpl.nasa.gov>

http://www.esa.int/esaCP/SEMUJM638FE_Life_0.html

Lichen survives in Space
European Space Agency
8 November 2005

One of the main focuses in the search for living organisms on other
planets and the possibilities for transfer of life between planets
currently centres on bacteria, due to the organisms simplicity and the
possibility of it surviving an interplanetary journey exposed to the
harsh space environment. This focus may develop to encompass more
advanced organisms following the results of an ESA experiment on the
recent Foton-M2 mission where it was discovered that lichens are very
adept at surviving in open space.
 
Lichens are not actually single organisms but an association of millions
of algal cells, which cooperate in the process of photosynthesis and are
held in a fungal mesh. The algal cells and the fungus have a symbiotic
relationship, with the algal cells providing the fungus with food and
the fungus providing the alga with a suitable living environment for
growth. Lichens are well known extremophiles, being able to survive the
harshest environments on Earth. The most striking element of the finding
is the complexity of this organism: it is multicellular, it is
macroscopic and it is a eukaryote, meaning that on the evolutionary
scale it is a much more modern organism than bacteria. In fact lichens
can be considered as very simple ecosystems.

The experiment which took place during the Foton mission was called
"Lichens" and was one of the exobiology experiments that was located in
the ESA Biopan facility. This exposure facility was located on the outer
shell of the Foton return module and, once at the correct orbital
altitude, opened to exposure the samples inside to open space, i.e.
exposed to vacuum, wide fluctuations of temperature, the complete
spectrum of solar UV light and bombarded with cosmic radiation. During
the Foton-M2 mission, which was launched into low-Earth orbit on 31 May
2005, the lichens, which came from two different species (Rhizocarpon
geographicum and Xanthoria elegans) were exposed for a total 14.6 days
before being returned to Earth. At the conclusion of the mission the lid
of Biopan was closed to protect the lichens from the conditions of
reentry. The Biopan was thereafter transported back to ESA's research
facility, ESTEC, in Noordwijk, the Netherlands to be opened.

The results of the experiment were presented by one of the experiment
team members, Dr. Rosa de la Torre from the Spanish Aerospace Research
Establishment (INTA) in Madrid, at a post-flight review in October at
ESTEC. Initial conclusions of the experiment, which is under the
scientific leadership of Prof. Leopoldo Sancho from the Complutense
University of Madrid, indicate that lichens have the capacity to resist
full exposure to the harsh space conditions, especially high levels of
UV radiation. Analysis post flight showed a full rate of survival and an
unchanged ability for photosynthesis.

This experiment opens up many possibilities for future research into the
possibility of transfer of life between planets. Follow up experiments
could focus on questions such as to what extent lichen, if transported
by a meteorite, can survive the reentry conditions into Earth's
atmosphere, i.e. what degree of shielding would be needed for lichen
samples to survive? The outcome of this Biopan experiment also suggests
that lichens might survive at the surface of Mars. Follow-up experiments
on ground and in space are bound to provide further answers to these
intriguing astrobiological questions.
Received on Tue 08 Nov 2005 04:09:33 PM PST