Could Mars have little microbes living in its dust? It seems difficult to imagine, with radiation bathing the planet's surface and no water running in at least most Red Planet regions. But NASA's Office of Planetary Protection is making plans for what to do if Martian microorganisms turn up.
At The Humans to Mars Summit in Washington, D.C., last week, on May 16, NASA Planetary Protection Officer Lisa Pratt briefly brought up the possibility of Mars microbes in a panel discussion. She said that future explorers should be concerned about possible biological agents in the dust, but she clarified that nobody knows that life exists for sure anywhere on the Red Planet — let alone on the Martian surface.
Life as we know it probably would do poorly in the radiation-filled Red Planet environment, which is exacerbated by the lack of a magnetic field that would have reduced exposure levels on the surface, said Jim Rice, a senior scientist at the Planetary Science Institute.
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But yet, "It's hard to say there's no life [on Mars]," he told Space.com. "You can't search every square millimeter on the surface."
Rice should know about that search, as his Mars Exploration rovers — better known to the public as Spirit and Opportunity — spent years trekking the Martian surface and discovered extensive evidence of past water in their landing zones. One piece of evidence they found was hematite, a mineral that tends to form in water.
Water is an essential component of life as we know it, although the presence of water doesn't mean there's definitely life. Also, the prevailing scientific wisdom suggests that most (if not all) of the Martian water evaporated eons ago, when the planet's atmosphere thinned due to continuing solar erosion of the atmosphere's molecules. The planet had no magnetic field to protect it from the sun's flow of charged particles.
Since Spirit's and Opportunity's finds after landing in 2004, other Mars missions continued the search for Red Planet life. The Mars Curiosity rover (which arrived in 2012) not only found signs of ancient water, but also discovered organic molecules — or molecules that can in some cases be associated with life. Forthcoming rovers called Mars 2020 (from NASA) and Rosalind Franklin (previously known as ExoMars, from the European Space Agency) aim to better characterize organic materials and Martian habitability after their launches in 2020.
And this doesn't even mention the many orbiting missions that have scoured the surface for waterborne minerals or water-shaped features from their perches above the Red Planet. One find from NASA's Mars Reconnaissance Orbiter remains controversial; the spacecraft saw streaks on some crater walls that were initially explained as salty water. Further analysis suggested that they may be dust streaks or contain small amounts of water that came from the atmosphere.
Lessons from Apollo
Rice cautioned that his field of expertise isn't biology, but his interdisciplinary research teams have put him in contact with people studying the possibility of life on other worlds. One example the public knows well is the quarantine that Apollo astronauts faced after coming back from the moon, he said.
In the 1960s and 1970s, NASA instituted quarantine protocols for the Apollo 11, 12 and 14 crews on the moon. (Apollo 13 never made it to the surface.) The agency lifted the quarantine requirement for the remaining Apollo missions, after no evidence of microbes was found.
No person has walked on the surface of any extraterrestrial world since 1972, with the final moon mission, Apollo 17. But we may be dealing with containment protocols on Mars sooner than we think, Rice said. NASA's Mars 2020 mission is supposed to cache promising samples for a possible sample-return mission in the near future.
There's a wrinkle, Rice said: "There's nowhere to bring them back to Earth. Nowhere exists for Martian sample return." A facility to contain the sample and safely examine it needs to be built, but design — let alone construction — is not something he's heard about yet.
Then, there's the question of how much a single sample-return mission would prove, he added. There's no way to sample every part of the Martian surface for life, so Rice said it's unclear if a sample-return mission — or even multiple sample-return missions — would be enough to satisfy concerns about astronaut health.
Future suit design
While NASA doesn't know for sure about microbes in Mars' dust, the agency is designing spacesuits for the moon, and for Mars, that are supposed to keep the dust away from humans as much as possible, said Lindsay Aitchison, a space technologist with NASA's Human Landing System program.
NASA aims to send astronauts back to the moon in 2024, and those astronauts will not use the Apollo-era spacesuits. While Apollo's suits worked well for short excursions of a few days, dust ended up being a limiting factor on those missions. The material ground into areas like wrist cuffs, making them hard to take on and off. It eroded soft surfaces and clogged zippers. Tools and rovers also experienced dust-related issues; on Apollo 17, for example, astronauts were forced to tape up an eroded rover fender with an unneeded map. The alternative was driving and getting showered with dust all through the journey.
In both locations, keeping dust away from astronauts will be critical. On Earth, we're used to dust that is soft. But on the moon, which gets little erosion compared to our own planet, dust has very sharp sides and quickly eats into everything around it. On Mars, the issue is more that the dust is chemically reactive and contains a potentially toxic compound called perchlorate — not in huge quantities, but in large enough concentrations that it could pose a concern for astronaut health, Aitchison told Space.com.
Either way, NASA is designing suits that will keep as much dust as possible away from the astronauts and the equipment inside their habitats.
There are many ways to contain dust, Aitchison explained. NASA could use a sort of "suit port" that permanently docks the astronaut suits outside the habitat, perhaps to the habitat itself or perhaps to a lunar or Martian rover. While this would keep the suits safely outside of living quarters, one limitation is figuring out how to repair the suits as they wear down. Astronauts doing the repair job would need to use backup suits, which offer more-limited mobility than just working in shirtsleeves.
Another option is using innovative technology to keep dust away from the suit in the first place. One idea would use electrostatic charges to repel moon dust (which is itself electrically charged). Dust-repelling possibilities have been studied at places such as the University of North Dakota or the Kennedy Space Center in Florida.
When asked if a lunar spacesuit could be used for Mars, or vice-versa, Aitchison explained there could be more similarities than we think. The moon and Mars have different gravity and pressure environments, to be sure, as well as different forms of dust. But Aitchison said the "same core architecture" could be used for items such as life support or pressure garments. While the specific spacesuit design would vary depending on the destination astronauts visit, some parts of the system could stay the same — reducing complexity and cost for future space missions.
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