UVolution, a photochemistry experiment in low earth orbit: investigation of the photostability of carboxylic acids exposed to mars surface UV radiation conditions.
The detection and identification of organic molecules on Mars are of prime importance to establish the existence of a possible ancient prebiotic chemistry or even a biological activity. To date, however, no complex organic compounds have been detected on Mars. The harsh environmental conditions at the surface of Mars are commonly advocated to explain this nondetection, but few studies have been implemented to test this hypothesis. To investigate the nature, abundance, and stability of organic molecules that could survive under such environmental conditions, we exposed, in low Earth orbit, organic molecules of martian astrobiological relevance to solar UV radiation (>200 nm). The experiment, called UVolution, was flown on board the Biopan ESA module, which was situated outside a Russian Foton automated capsule and exposed to space conditions for 12 days in September 2007. The targeted organic molecules [alpha-aminoisobutyric acid (AIB), mellitic acid, phthalic acid, and trimesic acid] were exposed with, and without, an analogous martian soil. Here, we present experimental results of the impact of solar UV radiation on the targeted molecules. Our results show that none of the organic molecules studied seemed to be radiotolerant to the solar UV radiation when directly exposed to it. Moreover, the presence of a mineral matrix seemed to increase the photodestruction rate. AIB, mellitic acid, phthalic acid, and trimesic acid should not be considered as primary targets for in situ molecular analyses during future surface missions if samples are only collected from the first centimeters of the top surface layer.
Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR 7583 CNRS, Universities of Paris 7 and Paris 12, Créteil, France. Fabien.Stalport@lisa.univ-paris12.fr
Fabien
F
Stalport
Yuan Yong
YY
Guan
Patrice
P
Coll
Cyril
C
Szopa
Frédérique
F
Macari
François
F
Raulin
Didier
D
Chaput
Hervé
H
Cottin
D000621:Aminoisobutyric Acids / Q000737:chemistry; D001565:Benzoates / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry*; D018534:Earth, Planet; D005118:Extraterrestrial Environment; D006207:Half-Life; D018535:Mars; D010777:Photochemistry / Q000379:methods*; D010795:Phthalic Acids / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D013499:Surface Properties / Q000528:radiation effects; D014233:Tricarboxylic Acids / Q000737:chemistry; D014466:Ultraviolet Rays
D000621:Aminoisobutyric Acids; D001565:Benzoates; D002264:Carboxylic Acids; D010795:Phthalic Acids; D014233:Tricarboxylic Acids; C100049:2-aminoisobutyric acid; C032279:phthalic acid; C069849:trimesic acid; C015339:mellitic acid