Jorge Vago, a planetary physicist and the head of science for part of the European Space Agency’s ExoMars program, suffered a setback on March 17, 2022. His team had been working for nearly two decades towards launching Europe’s first Mars rover, the Rosalind Franklin. However, the launch was suspended due to ESA’s suspension of ties with Russia’s space agency over the invasion of Ukraine. The launch was scheduled to take place at Kazakhstan’s Baikonur Cosmodrome, which is leased to Russia.
The Rosalind Franklin rover had previously faced budget issues, partner switches, technical difficulties, and the COVID-19 pandemic. The mission also included a Russian-made lander and instruments, which the member states of ESA would need funding to replace. The mission was in danger of being scrapped, but in November 2022, European research ministers pledged 360 million euros to cover mission expenses, including replacing Russian components. The mission is now expected to launch in 2028.
When the Rosalind Franklin rover finally lands on Mars, it will carry a suite of advanced instruments. The rover’s next-generation mass spectrometer is designed to analyze any carbon-containing material found underneath Mars’s surface. This instrument is the linchpin of a strategy to finally answer the most pressing question about the Red Planet: is there evidence of past or present life?
Scientists have designed the mass spectrometer to look for molecular patterns that are unlikely to be formed in the absence of living biology. Hunting for the patterns of life, instead of structures or specific molecules, has an added benefit in an extraterrestrial environment. It allows scientists to look for life as we don’t know it.
The Mars Organic Molecule Analyzer (MOMA), the rover’s mass spectrometer, is roughly the size of a carry-on suitcase. It is a labyrinth of wires and metal that analyzes organic molecules in Mars-like soils on Earth. The mass spectrometer has been shrunk substantially to fit into the rover, which must be rugged and lightweight.
MOMA will help scientists look for telltale signs of life on Mars by sifting through molecules in search of patterns that are unlikely to be formed any other way. For instance, lipids, which include building blocks of cell membranes, have a preponderance of even numbers of carbon atoms in nearly all living things, while nonliving chemistry produces a more equal mix of even and odd numbers of carbon atoms. Amino acids, the building blocks of proteins, can be created either by life or by non-biological chemistry. MOMA can differentiate between the left- and right-handed varieties of amino acids, making a case for living or nonliving origins in a way that prior missions could not.
MOMA cleverly circumvents the problem of perchlorate, which can degrade organic molecules at high temperatures, obscuring potential signs of life. The laser vaporizes and ionizes samples in one go, with pulses of light lasting under two nanoseconds, which is too quick for perchlorate reactions to occur. The laser also leaves molecules largely intact when giving them a charge to create ions, preserving weak chemical bonds that can be important for determining the structures of molecules in a sample.
MOMA won’t be the last word on whether life ever existed on Mars, but even the most tantalizing results would have to be confirmed by repeated experiments and lines of evidence from the rover’s other instruments. Some confirmatory work could also take place through other missions or even someday from analysis of Mars samples brought back to Earth.