Seeking Signs of Life on Mars: A Strategy for Selecting and Analyzing Returned Samples from Hydrothermal Deposits

Highly promising locales for biosignature prospecting on Mars are ancient hydrothermal deposits, formed by the interaction of surface water with heat from volcanism or impacts. On Earth, they occur throughout the geological record (to at least approx. 3.5 Ga), preserving robust mineralogical, textural and compositional evidence of thermophilic microbial activity. Hydrothermal systems were likely present early in Mars' history, including at two of the three finalist candidate landing sites for M2020, Columbia Hills and NE Syrtis Major. Hydrothermal environments on Earth's surface are varied, constituting subaerial hot spring aprons, mounds and fumaroles; shallow to deep-sea hydrothermal vents (black and white smokers); and vent mounds and hot-spring discharges in lacustrine and fluvial settings. Biological information can be preserved by rapid, spring-sourced mineral precipitation, but also could be altered or destroyed by postdepositional events. Thus, field observations need to be followed by detailed laboratory analysis to verify potential biosignatures. See Attachmen

Search for Organic Molecules at Oxia Planum with the Mars Organic Molecule Analyzer (MOMA) Investigation Onboard the ExoMars

International audienceOverview of the performances of the MOMA experiment onboard the Rosalinf Franklin Mars rover of the Exomars mission

Physicochemical changes in dietary fiber of green beans after repeated microwave treatments

The influence of microwave cooking/reheating on dietary fiber in green beans was investigated. The beans were analyzed after blanching and following repeated microwave treatment. Content and composition of dietary fiber as well as molecular weight distribution and viscosity of indigestible water-soluble polysaccharides (WSP) (Mw >1000) were determined. Total fiber content decreased only after the most severe microwave treatment, primarily due to losses of soluble dietary fiber (pectic polymers). Molecular weight and viscosity decreased considerably after the first microwave treatment. Repeated microwave treatments reduced the molecular weight further, but not the viscosity