Life on the Martian surface today is unlikely due to its thin atmosphere, although the possibility of extinct and subsurface life is possible and therefore, life on ancient Mars is an open question. Martian morphology and mineralogy indicate that Mars had surface water and active volcanoes in the past, which together imply warmer climates. Sulfur species have been linked to an increased greenhouse effect and offer additional UV shielding. Previous studies have used pulsed inputs of atmospheric sulfur species modeling the ancient Martian surface during periods of volcanic eruptions but leaving open the effect of atmospheric sulfur species during quieter periods of surface outgassing. Using surface mineralogy data from landers and orbiters, total volcanic sulfur deposition was estimated and an averaged upward flux for sulfur species found for the lifetime of volcanic activity on Mars. Using a one-dimensional photochemical model, concentrations of plausible atmospheric constituents including sulfur species were calculated to model different atmospheric conditions in Martian history. The amount of UV shielding obtained from the models determine UV survivability of Earth life. Earth bacteria D. radiodurans and cyanobacteria Chroococcidiopsis sp. 029 and an Archaean halophile sp. NRC-1 are shown as likely UV survivors in the modeled 350mbar atmosphere but questionable survival is found in thinner modeled atmospheres. Finally, reported surface data was used to determine likely surface locations on Mars for chosen microorganisms.
|School:||George Mason University|
|School Location:||United States -- Virginia|
|Source:||DAI-B 72/02, Dissertation Abstracts International|
|Keywords:||Cyanobacteria, Halobacterium, Mars, Martian atmosphere, Survivability, Ultraviolet radiation|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be