August 1, 2013.
Instrumentation such as the Chemistry and Mineralogy instrument (CheMin) on the ongoing Mars Science Lab rover mission is able to gather information from a sample almost immediately upon collection on the Martian surface; however, detecting molecular signs of extinct and extant life, or 28 STAR Closing Conference biosignatures, at low concentrations may require equipment with an even greater level of sensitivity. The capability of detecting biomolecules with a confidence acceptable to the scientific community exists on Earth, and at the current state of these technologies, it would be extremely challenging to miniaturize all relevant instrumentation for flight. The gathering and return of samples from the surface of Mars is likely paramount in the identification and confirmation of biosignatures. Sample containers would be expected to not corrode on the Martian surface or interact with the samples, and a gap of knowledge exists in this area. There are two parts to this study. The first is potentiodynamic polarization testing of titanium, stainless steel 304, and nitonol (A titanium/nickel alloy used in a prototype container seal) used for corrosion characteristics in Halite, Magnesium Sulfate, Perchlorate, Potassium Chloride, Hematite, MRS (a sulfate mixture), and Sulfuric and Hydrochloric Acid. Potentiodynamic polarization testing accelerates the corrosion process by applying a potential to the material of interest. The second is analysis of organic interactions with metals and substrates listed above by subjecting known quantities of organics placed on coupons to potentiodynamic polarization tests, then recovering the organics and comparing the results. All metals tested are interpreted to have very low corrosion levels in all substrates. The organics results should be a significant determinant of which metal to use considering container construction for future Mars caching and sample return missions.
Dr. Moogega Cooper
NASA Jet Propulsion Laboratory (JPL)
This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013 and Grant No. 0833353. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU).