Robotic missions have taken some steps to help prepare for future human exploration by studying the radiation environment on the way to Mars and at the surface. NASA’s Mars 2020 rover will perform a first demonstration experiment for in-situ resource utilization, generating oxygen from the Martian atmosphere. The biggest contribution to future human exploration has involved terrain mapping and climate characterization.

Life Detection at Mars' Surface

Several missions plan to launch toward Mars in summer 2020. Two in particular seek to advance the search for life by exploring beneath the surface: Mars 2020 and ESA’s Rosalind Franklin rover. The design of Mars 2020 is based on the Curiosity rover, but it has different instruments and an improved capacity to detect organic molecules thanks to its Raman spectrometers. Its goal is to drill and collect samples for future Mars sample return. The Rosalind Franklin rover is also equipped with a Raman spectrometer and has a drill that can collect a sample up to 2-meters deep for onboard analysis.

Raman spectrometers are widely used in Earth laboratories but have never before flown to Mars. They can identify the presence of carbon-containing compounds and the kinds of chemical bonds they contain. Mars 2020 has 2: SHERLOC, which is at the end of the robotic arm, and SuperCam, which is in the rover mast with the cameras. They will be able to operate on hundreds of different targets. In Rosalind Franklin, the spectrometer is called RLS and is in the rover’s internal sample analysis laboratory.

Raman spectroscopy alone cannot prove life existed on Mars. It is possible that one of the rovers could spot a carbon-containing molecule that is a perfect match for a known compound of biological interest. More likely, they will find evidence that some carboncontaining compounds are present. In all cases, additional analyses are required to determine the origin of the material. Some rover-based experiments can help to narrow this down, like the isotopic and chirality (molecule shape) analyses that Rosalind Franklin could perform.

Neither of the rovers can produce definitive evidence for life on Mars. We will need to do more detailed analyses that the rovers cannot perform, employing more powerful spectrometers or bringing new techniques like immunoassay detection and sample processing to extract and concentrate organics. Raman spectroscopy is a very good technique for selecting samples for further analysis. We will either need to bring samples back to Earth or bring a more powerful laboratory to the site, perhaps operated by human explorers.