Summary: Chemical markers of possible hot spots on Mars
Ah-San Wong and Sushil K. Atreya
Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan, USA
Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique (DESPA), Observatoire de Paris, Meudon, France
Received 16 January 2003; accepted 3 March 2003; published 15 April 2003.
 Although there is no evidence of active volcanism on Mars today, ``localized''
outgassing sources, the hot spots, may not be ruled out. If outgassing does occur
somewhere on Mars, water, carbon dioxide, sulfur species, methane, and to a lesser extent,
halogens would be the likely molecules of outgassing, based on terrestrial analogs. The
sulfur species, methane, and halogens have not been detected in the Martian atmosphere,
but the observations were averaged over large areas, which could result in substantial
dilution in abundances. If the interpretation of certain Mars Global Surveyor images
indicating recent ground water seepage and surface runoff [Malin and Edgett, 2000] is
correct, it may imply that Mars could still be active internally in some places from time to
time, and outgassing of the abovementioned species may occur with or without the water
seepage. Moreover, if the tentative detection of formaldehyde (CH2O) in the equatorial
region of Mars [Korablev et al., 1993] is confirmed by future observations, it would imply
at least local outgassing of methane, whose oxidation results in the formation of CH2O.
Considering the possibility of outgassing from some localized hot spots, we have