Evidence of life on Mars

 Searching evidence for life which might have existed on Mars

For decades, the search for extraterrestrial life has relied on complex missions, new instruments and billion-dollar budgets. After spending so much time on the Martian surface, the Opportunity rover sent troves of data back to Earth for scientists around the world to analyse in hopes of learning more about the red planet’s geology and atmosphere, past and present. One of those scientists was John Grant, a planetary geologist at the National Air and Space Museum. His aim was to find evidence of conditions which could have supported life on Mars. “It seems that all the necessary pieces are there on Mars for life to have existed,” John said. “We’ve found that there are areas on Mars where water was flowing in the distant past as well as relatively more recently. That’s evolved my thinking from ‘okay, so there was some water long ago' to ‘there were some big lakes there’ to ‘there were habitable environments and maybe life'.” But now, a PhD student and his supervisor at Imperial College London have shown that a device already sitting on Mars could answer one of humanity’s biggest questions: Is anything alive out there, right now? The breakthrough comes from Solomon Hirsch and Professor Mark Sephton of Imperial’s Department of Earth Science & Engineering. The gas chromatograph-mass spectrometer (GC-MS) is an instrument that is already installed on the Curiosity rover and planned for use on the ExoMars Rosalind Franklin rover. The team realized that this common piece of equipment can be used in an entirely new way.

Space exploration is a hell of a show, there are surprises around every corner. If we were to find evidence of life on Mars, it would surely make some of us start to question our own existence. It would tell us more about how life evolves. We only have one data point so far, and that’s Earth. There’s been this question since humanity first started to ruminate on big ideas about whether we’re alone in the universe. If you only have to go one planet away to find life, it speak volumes about how life may be distributed throughout the universe. It also changes how and why we explore in and outside our solar system in the future. It also provides us, as humans, some perspective on our place in the universe. “Space agencies such as NASA and ESA don’t know their instruments can already do this,” Sephton said. “Here we have developed an elegant method that rapidly and reliably identifies a chemical bond that shows the presence of viable life.” 

The GC-MS has a long pedigree in planetary science, with earlier versions flying on the Viking missions of the 1970s. Traditionally, scientists have used it to analyse gases released from rocks and soils. But Hirsch and Sephton discovered it could also detect fragile molecular bonds inside the membranes of living cells, a marker of life that is present only while an organism is alive or has very recently died. The technique focuses on intact polar lipids (IPLs), the molecules which make up the external membranes of bacteria and more complex cells. These molecules degrade within hours of death, making them a reliable sign of living organisms. When fed into the GC-MS, IPLs leave behind a sharp, unmistakable spike on the instrument’s readout. “If we find signs of life beyond Earth, the first question will be: Is it living right now?” Hirsch said. “It’s thrilling to think that the technique we developed here could be used to help answer that question.” Researchers unexpectedly found a clear biosignature in polar lipids using GC-MS, with equipment already deployed on space missions. If scientists ever detect such a spike on Mars or another world, it will provide direct evidence of active life rather than long-extinct biology.

Mars is not a welcoming place for life. Its thin atmosphere, freezing surface temperatures and constant radiation from space make survival difficult. Visiting Mars can have implications in other fields. Medical doctors have a completely different set of rationales. How does the human body respond to radiation? If we're ever going to get off the Earth and be an exploring species, Mars is one of the places where we should start. But still, we haven’t gotten to the question of “why?” Why go through all this trouble to study space at all, when we’ve got so many problems to solve here on Earth? Hirsch admits that expectations of finding organisms on the planet’s surface are low. But he points out that life is resourceful. “Life finds amazing ways to survive in extreme circumstances,” he noted. Future missions will also dig deeper into Mars’ crust, where conditions may be more favourable. The Rosalind Franklin rover, part of the delayed ExoMars mission, will drill several feet beneath the surface, where microbes could remain shielded from radiation and potentially active. Beyond Mars, icy moons like Europa and Enceladus are even more promising. They are known to host subsurface oceans and erupt plumes of water vapour into space. Sephton envisions the method being applied there too. “Our active life detection method could be deployed on Mars and the plumes of icy moons in the outer solar system, or in samples returned to Earth from potential alien biospheres,” he said.

The method could also help right here at home. Sephton sees the technique as both cost-effective and versatile. Instead of designing entirely new instruments for each mission, scientists could repurpose existing ones to do more than originally intended. Teams preparing to analyse samples returned from Mars are planning multimillion-dollar facilities to screen for possible life. A quick and simple GC-MS test would make the task more efficient, flagging which samples deserve deeper analysis. It’s an approach that may accelerate discoveries without requiring decades of waiting for the next mission to launch. It shows that sometimes the tools for transformative science are already in our hands – it just takes a new perspective to see them differently.

Whether or not life is discovered, the technique itself represents a leap forward. The search for extraterrestrial life is often portrayed as a grand adventure, requiring futuristic technology and vast budgets. Hirsch and Sephton’s work offers a humbler but no less profound possibility: the answer to one of humanity’s oldest questions may already be riding around the Martian surface waiting to be asked the right question in the right way. As Hirsch put it, the possibility remains remote but real: “Our expectation of finding things alive on the Martian surface is low due to the hostile temperature and radiation conditions. Still, we aren’t ruling out the possibility.” And if life does exist, this new approach may be the simplest way to prove it. By exploring things beyond Earth, we inspire people to get interested in and involved in science. Reaching Mars will inspire a lot of people around the world and might bring some new era of thought process about the universe.