NASA’s Curiosity rover on Mars. Image : NASA/JPL-Caltech/MSSS

Whether it’s rovers rolling about on Mars, probes drilling into asteroids, or Tesla Roadsters drifting through space, it’s clear that our activities in the Solar System are changing. Accordingly, methods and rules to prevent our germs from spreading beyond Earth need to be updated, according to a new report aimed squarely at NASA.




Current NASA policies designed to protect planets and other Solar System bodies from contamination during exploration missions are sorely out of date, according a report put out this week by the National Academies of Sciences, Engineering, and Medicine (NASEM). The report, titled “Review and Assessment of Planetary Protection Policy Development Processes,” claims that current processes and rules are “inadequate to respond to progressively more complex Solar System exploration missions,” especially in the current cash-strapped era.

No doubt, spreading our microbes to other planets, moons, asteroids, and comets is totally not cool. Inadvertently and unknowingly contaminating other celestial objects with life forms—bacteria, viruses, or tiny organisms like tardigrades—would make the task of detecting extraterrestrial life on nearby celestial bodies next to impossible; while exploring the sandy surface of Mars, or the subsurface oceans of Enceladus or Europa, astrobiologists would struggle to distinguish native life from life that originated on Earth. The presence of DNA on another planet or moon is no guarantee that it came from Earth, as this self-replicating molecule may constitute a fundamental building block of life across the entire cosmos.


The flip-side of this coin is that a returning space mission, say a probe with samples from Mars or an asteroid, could threaten life on Earth. It’s unlikely, but we simply don’t know the risks.

Scientists have been aware of the forward-and-back contamination problem ever since we began shooting our rockets into space. In 1967, the United Nations forged the “Outer Space Treaty,”to which the United States is a signing member. Countries bound by the treaty “shall pursue studies of outer space, including the Moon and other celestial bodies, and conduct exploration of them so as to avoid their harmful contamination, and also adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter,” as stated in Article IX of the treaty. Nice words, but the treaty was scarce on details.

To keep its space-bound instruments clean, NASA refers to guidelines established by the Committee on Space Research, an international organization otherwise known as COSPAR. NASA currently has a planetary protection office to make sure it’s honoring COSPAR guidelines, but these rules aren’t legally binding, and there’s nothing, outside of science ethics, to prevent NASA from straying off course.

It’s for these and other reasons that the NASEM committee says NASA is not ready to deal with future missions such as the Mars Sample Return project and journeys to explore the icy moons of Jupiter and Saturn, according to the report. What’s more, NASA hasn’t developed a planetary protection policy that speaks to a human mission to Mars, which could happen as early as the 2030s.


“Moreover, the current US government process to oversee samples returned from Mars and elsewhere dates back to the Apollo era and is out of date,” according to a NASEM press release. “The committee recommended that NASA’s agency-wide planetary protection strategic plan prepare for the policy development challenges that sample return and human missions to Mars are creating, as well as revise or replace its provisions for engaging relevant federal agencies in developing protection policies for returned samples.”

The NASEM committee says NASA should still honor the Outer Space Treaty and the role played by COSPAR, but in addition, the space agency should develop a plan to manage the way it implements its planetary protection policy, seek the advice of outside experts, and develop a long-range forecast for future missions to other planets, among other recommendations.


The report also mentions the private sector, which is playing an increasingly important role in how we explore space.

“Private-sector space exploration activities are another reason why planetary protection policies need re-examination,” the authors write. “The only commercial space missions that are currently required to undergo rigorous spacecraft decontamination procedures are those that might go to Mars, because Mars is the only body of current interest to private-sector entities that is potentially capable of harboring life.”


In light of this, the NASEM committee recommends that planetary protection policies and efforts to prevent forward-and-back contamination should apply equally to both government-sponsored and private-sector missions. The US government, the report states, will be responsible for enforcing these standards on private companies. Good luck with that.

This is a welcome report, given where NASA and the private-sector is headed over the next few decades. These recommendations make sense, at least for the time being. Sure, NASA should update its policies and practices, and the private-sector should follow suit, but it’s not clear if any of this will work, particularly in the long-term. As we venture further out into space, the odds are that we’ll eventually contaminate another world, despite our best intentions.


We may not win this battle, but it’s still worth fighting.

[National Academies of Sciences, Engineering and Medicine]