Debate is growing over whether Martian samples pose a threat to Earth

Less than a decade from now, a Mars spacecraft may be swaying close to Earth to drop a precious cargo: samples of Red Planet rock, soil and even air to be scanned for signs of alien life by the small army of researchers here on our site. Terra Firma. Organized by NASA and the European Space Agency, this fast-paced, multi-billion dollar project, officially known as the Mars Sample Return (MSR) campaign, is the closest thing to the Holy Grail that planetary scientists have ever sought. .

In many ways, the MSR is well underway: NASA’s Perseverance rover is cruising around an ancient river delta on Mars’ Jezero Crater, collecting selected samples of potential astrobiological interest for future capture by the Fetch Rover. Then there’s the design and testing of the Mars Ascent Rover to lift those retrieved samples into orbit for later transport back to Earth as it is well underway. But there is an important aspect of the project that remains alarmingly unresolved: How exactly should the returned samples be handled and at what cost, given the potential risks of somehow contaminating Earth’s biosphere with imported Martian insects?

The elusive answers to these questions could profoundly shape not only the MSR but also the hoped-for continuation of sending humans to the surface of Mars. Can astronauts live and work there without inadvertently introducing terrestrial microbes to the Red Planet? And perhaps most importantly, can they eventually go home with the certainty that they are not carrying microscopic Martian roving? The protocols developed for MSR will be a critical component of resolving these final pitfalls.

dangerous work

MSR’s current NASA proposal calls for an interplanetary ferry not yet built to launch a conical, sample-packed capsule — called the Earth Entry System — above our planet’s atmosphere. The capsule will then endure a fiery descent to the ground, without a parachute, and eventually descend to the bottom of a dry lake within the Utah test and training range. Despite the impact at nearly 150 kilometers per hour, the capsule will be designed to keep its samples intact and isolated. Once recovered, it will be placed in its protective environmentally controlled container and then shipped to an off-site facility to receive samples. Such a facility could resemble today’s biolab that studies highly infectious pathogens, and includes multi-layered decontamination procedures, air purification systems, negative pressure ventilation, and a myriad of other safeguards.

Citing the findings of multiple expert panels, NASA currently considers the environmental and public safety risks of this proposal to be “extremely low”. But not everyone agrees. Earlier this year, the space agency requested public comment on a draft associated environmental impact statement, and received 170 observations, most of them negative regarding the concept of direct-to-Earth express mail for Mars collectibles.

“Have you lost your mind? Not just no, but hell no,” one commenter suggested. Another said, “No nation should put the entire planet at risk.” And the last third is his opinion, “Public opposition will surely escalate drastically as far as I know [NASA’s] Intentions spread beyond the smaller space community.” Several respondents suggested that any sample shipment should first be received somehow and studied outside Earth—an approach, while certainly prudent, that could easily become a logistical and financial nightmare.

Compare this with the frank opinion of Stephen Benner, a prominent astrobiologist and founder of the Foundation for Applied Molecular Evolution in Alachoa, Florida: “I see no need for long discussions about how to store samples from Mars once they reach the planet,” he says. That’s because space rocks hit Mars and routinely release material that eventually ends up on Earth. Benner says current estimates are that about 500 kilograms of Martian rock land on our planet each year. He even has a large five-gram piece of Mars adorning his desk which indicates this fact.

“In the more than 3.5 billion years since life appeared on Earth, trillions of other rocks have made similar journeys,” Benner says. “If Martian germs are present and can damage the Earth’s biosphere, then it has already happened, and a few extra kilograms from NASA won’t make any difference.”

Referring to his service on many of the same expert committees that NASA has now cited for its “extremely low” assessment of MSR’s risks, Boehner says the space agency appears caught in a PR trap of its own making, and the supposed complexities are bound to be discussed endlessly. For what really should be considered a simple and stable science. NASA now knows “how to look for life on Mars, where to look for life on Mars and why the likelihood of finding life on Mars is high,” he notes. “But NASA committees, seeking consensus and consensus about the fundamentals of chemistry, biology, and planetary science that should drive the search for Martian life, are displacing science in favor of discussions on these issues,” unnecessarily increasing costs and delaying mission launches.

“They ended up ensuring that NASA would never do any life-discovery missions,” Benner says.

This illustration shows a concept for a proposed NASA rocket and lander assembly that would play a key role in returning Earth samples of Martian material collected by the rover.  This sample retrieval probe will carry a small rocket (about 10 feet or 3 meters long) called the Mars Ascent Vehicle to the surface of Mars.  After using a robotic arm to load the rover's sealed sample tubes into a container in the rocket's nose cone, the probe will launch the Mars Ascent Rover into orbit around the Red Planet.  The probe and rocket are part of the multi-mission Mars sample return program planned by NASA and the European Space Agency (ESA).  The program will use several robotic vehicles to pick up and transport sealed tubes containing Martian samples already collected by NASA's Persistent Probe, for transport to laboratories on Earth.
Credit: NASA/JPL-Caltech

Warning costs

Such statements reflect a growing sense of urgency among American planetary scientists to make MSR a reality. In April, NASA received its most recent Decadal Survey of Planetary Science and Astrobiology, an influential report released by the National Academies of Sciences, Engineering, and Medicine that outlined the immediate future priorities for the field. One of the main recommendations in the report calls for the agency to strengthen its plans for handling the MSR samples, with a focus on preparing the Mars Sample Receiving Facility in time to receive material from the Red Planet by 2031.

To meet that deadline, NASA must begin designing — and building — such a facility immediately, says Philip Christensen, a professor at Arizona State University and co-chair of the new decadal survey’s steering committee.

“Our recommendation was not to go and build a fancy reception facility that is too complex and too rich with tools,” Christensen says. “Instead, keep it as simple as possible. The first task is to check that the samples are safe, and then let them go to laboratories around the world that already have very advanced equipment.”

John Rommel, a retired astrobiologist who previously assisted with NASA’s “planetary protection” efforts on its interplanetary missions, agrees that simplicity can save time but at uncertain costs. Nobody wants to spend all the money in the world on the Taj Mahal for it [sample-return] Science, he says. However, building a naked facility could backfire, by not allowing scientists to properly investigate whether any samples returned contained evidence of life.

More importantly, Rommel says, it simply isn’t true that we know enough about Mars to determine MSR’s risk of interplanetary infection. “In the first place, we don’t know everything we want to know about Mars. That’s why we want the samples,” Rommel says. “We continue to find Earth beings doing very interesting new things from the point of view of possible life elsewhere. So why don’t we think we need to be careful? The answer is we need to be careful, as emphasized over and over again by the National [Academies]…. People should have some kind of respect for the unknown. If you have that respect, you can do a credible job, and the public will get a good watch.”

all together now

Although MSR’s true risks of interplanetary environmental catastrophe may be unknown, the threat posed by negative public opinion to the mission is clear to most scientists involved. However, interaction with the audience should be welcomed, says Benny Boston, an astrobiologist at NASA’s Ames Research Center. What better way to push research forward to fill knowledge gaps about planetary protection, you say, than to get people interested in the topic and its great perils? “This will allow us to optimally protect Earth’s biosphere and humans while still making the most of analyzes of Mars samples to answer scientific questions,” Boston says.

Similarly, while the frightening effect of harsh handling restrictions on MSR samples seems more likely than some other mundane outbreak of lax biosafety protocols, some argue that, in absolute budget terms, erring on the side of caution is not so costly.

According to astrobiologist Cassie Conley, who succeeded Rommel as NASA’s Planetary Protection Officer from 2006 to 2017, by the time the MSR capsule hit the bottom of a dry lake in Utah, “taxpayers had invested at least $10 billion to bring in these samples.” to Earth. So, wouldn’t it be worth spending 1 percent more to build the best possible facilities and hardware to study these samples while also making sure that MSR doesn’t do anything bad to the only planet we can live on?”

However, an additional concern complicates the debate: MSR is no longer alone in its quest to obtain new rocks on the Red Planet, and other projects may not adhere to its emerging rules. China recently announced its independent plans to bring Martian material directly to Earth, possibly ahead of NASA/ESA’s Mars sample return campaign, and there’s also the “wild card” of Elon Musk’s Mars-focused effort that leads to human flights to Mars and back in Much sooner than most experts expect.

China’s entry in particular worries Barry DiGregorio, an astrobiologist and founding director of the International Committee Against the Return of Mars Samples (ICAMSR). “unless [returning samples from Mars] It is being conducted as a global effort in order to share the results in real time with all the space-faring nations rather than it being a national target, no country will know what the other has found or the problems they are having with containment.”

That’s why DiGregorio stresses that a priority must be given to ruling out the possibilities of each sample to harm the Earth’s biosphere before returning it to our planet — something best done on a dedicated space station or even an astrobiology research lab built as part of a lunar base. “Of course, given rising global geopolitical tensions, this concept is likely to be difficult to sell” – but now is a “critical time” to consider it, he adds.