Arnaud Buch

Organic matter preserved in 3-billion-year-old mudstones at Gale crater, Mars

Measuring martian organics and methane The Curiosity rover has been sampling on Mars for the past 5 years (see the Perspective by ten Kate). Eigenbrode et al. used two instruments in the SAM (Sample Analysis at Mars) suite to catch traces of complex organics preserved in 3-billion-year-old sediments. Heating the sediments released an array of organics and volatiles reminiscent of organic-rich sedimentary rock found on Earth. Most methane on Earth is produced by biological sources, but numerous abiotic processes have been proposed to explain martian methane. Webster et al. report atmospheric measurements of methane covering 3 martian years and found that the background level varies with the local seasons. The seasonal variation provides an important clue for determining the origin of martian methane. Science, this issue p. 1096, p. 1093; see also p. 1068 Complex organic compounds may have been detected by the Curiosity rover in ancient martian sedimentary rocks. Establishing the presence and state of organic matter, including its possible biosignatures, in martian materials has been an elusive quest, despite limited reports of the existence of organic matter on Mars. We report the in situ detection of organic matter preserved in lacustrine mudstones at the base of the ~3.5-billion-year-old Murray formation at Pahrump Hills, Gale crater, by the Sample Analysis at Mars instrument suite onboard the Curiosity rover. Diverse pyrolysis products, including thiophenic, aromatic, and aliphatic compounds released at high temperatures (500° to 820°C), were directly detected by evolved gas analysis. Thiophenes were also observed by gas chromatography–mass spectrometry. Their presence suggests that sulfurization aided organic matter preservation. At least 50 nanomoles of organic carbon persists, probably as macromolecules containing 5% carbon as organic sulfur molecules.

Operations of the Sample Analysis at Mars instrument suite onboard the Curiosity rover

The Sample Analysis at Mars instrument suite, onboard the Curiosity rover, has been analyzing the martian environment since August 05th 2012, as one of the main tools of the Mars Science Laboratory mission. nThis suite is composed of three independent but interoperable instruments, namely a Quadrupole Mass Spectrometer, a nTunable Laser Spectrometer and a Gas Chromatograph, plus a sophisticated Sample Manipulation System. nSAM is used to analyze soils, rocks and atmosphere. For instance, it detected in situ martian complex organics for the first time, provide us with a several years survey of the atmospheric composition and helped understand how the martian environment evolved nthrough the planet history. At 40 kg, it represents half of the scientific payload weight of Curiosity and is one of the two analytical instruments of the mission. This instrument suite is the result of an international collaboration between the NASA Goddard Space Flight Center, the NASA Jet Propulsion Laboratory and a consortium of French laboratories supported by the Center National d’Etudes Spatiales (the French space agency). nThis contribution will present the organization of the SAM operational workflow from the ground infrastructure, to flight operations and nlaboratory supporting work. It will also describe how the CNES hosts and supports the SAM team during this exciting mission.