Date of Graduation


Document Type


Degree Name

Bachelor of Science

Degree Level



Biological Sciences


The search for life on Mars has been one of the more intriguing pursuits of NASA and astrobiologists over the last fifteen years. With the help of NASA’s Martian landers and orbiters, discoveries about the red planet have narrowed the range of possible known organisms that could survive on its surface or beneath its icy crust. The discoveries of water ice, methane, and perchlorate on Mars have excited astrobiologists and prompted experimentation on Earth to help determine whether life could exist on Mars. Methanogens seem an ideal candidate to be the organism responsible for biological production of methane on Mars, and many experiments have shown their potential to grow in different Mars-like conditions. In this experiment, four different species of methanogens were grown under the effects of the oxidizing agent perchlorate. Perchlorate in Martian soil was a discovery made by the Phoenix Lander and hints at the possibility that aqueous brine could exist in the Martian subsurface. It was hypothesized that increasing concentrations of perchlorate would lead to decreasing levels of methane production in each species of methanogen. In all four levels of perchlorate concentration (0, 1%, 5%, and 10%), all methanogens produced methane. However, the control and 1% groups showed significantly more metabolic activity than the higher concentration groups. This supported the initial hypothesis, but cannot conclusively determine the inability for methanogens to grow with perchlorate under the Martian crust.