Exploring Mars in search for life before it is too late

In the next few decades, space agencies are hopeful that humanity may take its first steps on Martian soil. Yet according to Alberto Fairén at the Astrobiology Centre in Madrid, Spain, these missions could have disastrous consequences for our ability to study any life which may be present on Mars. Through his research, Fairén proposes a ‘New Deal’ for Mars exploration, which would involve ramping up the search for life with uncrewed spacecraft. If these measures are taken, he hopes that astrobiologists will have just enough time to discover and study life on Mars, before the arrival of humanity risks wiping it out forever.

Since the 1970s, planetary scientists have explored the Martian surface with remotely operated landers and rovers. Equipped with cutting-edge instruments, these spacecraft have now allowed scientists to study our planetary neighbour in extensive detail, gaining insights ranging from the chemical composition of its soil, to recurring patterns in its climate. The pace of this research shows no sign of slowing: with NASA’s Curiosity and Perseverance Rovers continuing to provide a flood of valuable data, and ESA’s Rosalind Franklin ExoMars rover now scheduled to land in 2029. In the coming decades, however, astronomers are increasingly hopeful that humanity could finally take its first steps on the red planet, heralding an exciting new era of exploration.

A successful landing would undoubtedly be one of humanity’s greatest achievements. Yet for Professor Alberto Fairén at the Spanish Astrobiology Centre, it would also present urgent concerns for future studies of Mars, which have rarely been discussed so far.

Stringent decontamination

Every time a rover is despatched to explore Mars, space agencies like NASA and ESA will take painstaking efforts to sterilise it, ensuring not a single living cell is launched into space. For future crewed missions, however, decontamination procedures will become far more difficult. ‘Because it is impossible to ensure that all human-associated processes and operations are conducted within entirely closed systems, it is inevitable that terrestrial microorganisms will accompany human crews to Mars’, Fairén explains. ‘Accidental release of biomaterials is bound to happen as a result of human activity on Mars, and these microbial hitchhickers may find ways to adapt and survive on the planet.’ If this happens, Fairén thinks it could have disastrous consequences for astrobiology.

Life on Mars?

The question of whether life could exist on Mars has long remained one of the greatest mysteries in astronomy. While no conclusive evidence has been gathered so far, many researchers have yet to give up hope. According to some astrobiologists, there remains a possibility that life may have arrived on Mars from other planets like Earth, or even from beyond our Solar System. These vagrants may have hitched a ride aboard asteroids launched by violent events such as asteroid impacts or volcanic eruptions. Alternatively, Mars may still host the remnants of an indigenous biosphere which thrived in the distant past, when the planet was likely far more hospitable to life.

In either case, hardy lifeforms could still be holding on in safe and secluded environments: perhaps deep below the surface, within pockets of liquid water. If these ecosystems are ever discovered, it may be key to answering some of our most fundamental questions surrounding the abundance of life throughout the Universe, as well as the origins of life itself.

An incalculable loss

According to Fairén, the possibility of crewed missions to Mars in the not-too-distant future would risk contaminating these ecosystems with Earth-based life. If these microbial intruders manage to out-compete Mars’ native life, it could ultimately be wiped out before we ever get a chance to study it.

If this happens, there will be no second chance: our single greatest opportunity to study life beyond Earth will be lost forever. ‘The consequences of such catastrophe will resonate for centuries in our science, philosophy, religious concepts, ethics, and society in general’, Fairén says.

For Fairén, this disastrous outcome is by no means unavoidable – but the window of opportunity to avoid it may be closing fast. ‘The good news is that we know exactly what we need to do to address this formidable challenge: to robotically explore the planet in search for Martian life before sending terrestrial life to Mars’, he explains. ‘The bad news is that we are running out of time to do it.’ If proactive steps aren’t quickly taken to study Martian life before a new era of crewed exploration begins, Fairén ultimately believes that our loss of potential knowledge would be incalculable.

Planetary protection

To avoid this outcome, Fairén advocates the development of a ‘New Deal’ which will better ensure that, if life is present on Mars, it can be discovered and extensively studied by uncrewed crafts chartered by all space-faring nations and their private partners, before the arrival of our first astronaut missions.

Before crewed missions can happen, Fairén has identified the need for rapid advances in three key areas. ‘Firstly, a redefinition of Planetary Protection and Special Regions is required for the case of Mars’, he describes. With this new definition, Fairén suggests that researchers could identify areas of the Martian surface which could feasibly be studied with rovers and landers within the next 10 to 20 years.

‘Secondly, we need to develop new robotic tools for the characterisation of complex organic compounds’, Fairén continues. For astrobiologists, these biochemical building blocks are a key sign that alien ecosystems could exist or have existed nearby. Therefore, identifying their presence on Mars will be critical for the discovery of life. Finally, ‘We need to change from the present generation of SUV-sized Mars landers and rovers to new robotic assets that are much easier to decontaminate.’ While these far more compact ‘microlanders’ would be much further limited in their sensing capabilities, they would also be much easier to build and launch into space, making them available in far greater numbers.

Together, Fairén describes these three measures as the minimum requirements to preserve the possibility of finding life on Mars before the arrival of astronauts. If the developments he proposes can be made within the next 10 to 20 years, he remains hopeful that astrobiologists will have the best possible chance to study whatever life may exist on Mars, before it is too late. All the same, the deadline is looming.

The Mars Anthropocene

Over the past 10,000 years or so, human activity has fundamentally transformed the landscape and ecosystem of our own planet. Some geologists now propose that this period – a brief blip in time compared with Earth’s overall history – constitutes its very own geological epoch, named the ‘Anthropocene’.

As Fairén describes, ‘If the pace of current efforts to send humans to Mars is any indicator, the impact of human activities may soon be as quantifiable on Mars as it is on Earth, and the Anthropocene could soon make its debut as the first multiplanetary geological period.’ Through his latest research, Fairén has considered just how transformative these changes would be.

After landing on Mars, humans would soon leave many of the same fingerprints which characterise the Anthropocene on Earth, including buildings and factories, changes to the atmosphere, and new layers of ice and sediment. As this happens, the mining of raw materials and the harvesting of ice for water resources would spread Earth-based microbial life to every corner of the planet. Altogether, these would be the first global-scale changes seen on Mars since it lost most of its once-abundant atmosphere, billions of years ago.

If this anthropogenic transformation takes place, Fairén predicts that any hypothetical Martian life may still be able to survive – shielded to an extent by the sparsity of Mars’ atmosphere, which would make it more difficult for Earth-based microbes to spread by themselves. However, the ability of native ecosystems to hold out against these hardy invaders would still be far from certain.

In predicting the changes the Mars Anthropocene could bring, Fairén highlights just how important it will be for astrobiologists to discover and document uncontaminated Martian life, before it is too late. If the New Deal he proposes is adopted by national space agencies and private companies, there may still be time to make this goal a reality. ‘This is one of the defining moments of our generation: previous generations did not face this situation’, he says. ‘Future generations will need to live with the consequences of our decisions made today.’