Mars Missions Can Prevent Microbe Contamination, Protect the Red Planet says USU Professor

The surface of Mars

By Ian Neligh


Despite the multiple attempts to uncover its secrets, the one guarantee in the search for life on the freezing, radiation-blasted red surface of Mars is the absence of Earth-born microbes thanks to a planetary protection policy that has been in place for more than four decades. The policy’s intent is to keep microbes from contaminating and compromising investigations into the presence of life on Earth’s celestial neighbor.  

According to a recent National Academies of Sciences, Engineering and Medicine (NASEM) report, “Evaluation of Bioburden Requirements for Mars Missions,” the risk of harmful contamination of Mars with Terran-based microbes during robotic missions is lower than previously expected due to several factors, including its harsh desiccated environment and high levels of ultraviolet C (UVC) radiation.  

The findings were published by NASEM’s Committee on Planetary Protection (CoPP), including member Michael Daly, Ph.D., professor of Pathology at the Uniformed Services University.  The report identified areas on the planet that were more suitable for future missions and required less stringent bioburden requirements. 

A picture of Mars
The report titled "Evaluation of Bioburden Requirements for Mars Missions"
authored by the Committee on Planetary Protection identifies areas on the
planet more suitable for future missions that have less stringent bioburden
requirements. (Photo credit: NASA)
“The biggest take-home message is that we can begin to plan missions to Mars with lower levels of
planetary protection than were used before,” says Daly. “And this is very important because there is a financial burden to planetary protection which can have a significant impact on mission costs.”

Daly is one of two microbiologists on the committee and was selected, in part, because of his background in the study of extremely desiccation-tolerant organisms and their ability to survive vast doses of radiation. 

The study was conducted at the request of NASA because of what is expected to become an increase in robotic, commercial, and even crewed missions to Mars in the near future and the importance of mitigating contamination.

“Harsh conditions of much of the surface of Mars - including the UVC radiation environment, paucity of persistent liquid water, and humidity-and-temperature cycles - make survival, growth, and proliferation of terrestrial organisms on the surface unlikely,” according to the report. “Likewise, portions of the Martian subsurface, down to a depth of approximately 1m and lacking evidence of ice, are not environments where terrestrial organisms could proliferate. Thus, the presence of terrestrial organisms on the surface or in these portions of the subsurface are, by themselves, unlikely to compromise future investigations of Martian life.”

“In other words, you don’t have to worry so much when you launch probes to Mars from Earth because you can rely on the very high levels of radiation that are striking the surface of Mars to do a lot of the sterilizing work for you — at least on the surfaces,” Daly says.

According to Daly, now that there are many more missions being planned, not only by the United States but internationally and even including focusing on the moons of Mars, the report identifies ways to reduce the levels of planetary protection and associated costs without losing scientific integrity. He adds, the reason the lowered protections can now be put in place is because of a much deeper and broader understanding of the hostile environments on the red planet’s surface.

USU Pathology professor Dr. Michael Daly points to a picture of Deinococcus radiodurans, a bacterium famous for its extreme resistance to radiation. Daly is a member of the Committee on Planetary Protection. (Photo credit: Helen Hocknell)
USU Pathology professor Dr. Michael Daly points to a picture of Deinococcus radiodurans, a bacterium famous for its extreme resistance to radiation. Daly is a
member of the Committee on Planetary Protection. (Photo credit: Helen Hocknell)

“If you can lower the risk level, you can then plan accordingly to reduce the cost of your mission,” Daly says. “… So we have to take great care now making sure these missions can advance and progress but without harmfully contaminating wherever they’re going.”

He says the possibility of contamination during later manned missions to the planet tentatively set for sometime in the 2030s provides an entirely new set of vexing microbial questions.

“That’s a whole different kettle of fish,” Daly says. “Because we are just bags of microbes.”

Additionally, samples from the Perseverance Rover, which landed on Mars in February in the Jezero Crater with its mission to hunt for signs of past life, will potentially arrive back on Earth in 2031.  Daly says CoPP will then need to work on what will be necessary to protect Earth from back-contamination, which he says is paramount.

“Of course planetary protection will be very critical in that case because we do not want to contaminate Earth with potential martian microbes,” says Daly. “It sounds very science fiction, but the possibility is real. We have to be absolutely certain about what we are doing.”