Tags Barry DiGregorio Mars rock geology rock varnish MSL various Mars rovers terrestrial rock varnish returning to the Moon Mars liquid water planetary protection Mars sample return mission sample return risks Mars 2020 NASA life detection experiments life detection instrumentation Mars cross contamination Article 9 of the OST Mars rover microscopes Mars Mount Sharp findings NASA and Mars life detection Dr. Gil Levin Viking Guest Barry DiGregorio Tagline Mars rocks, geology, and more View the discussion thread.