Planetary quarantine“Planetary Quarantine”: Risks of Alien Contamination

In Michael Crichton’s 1969 novel The Andromeda Strain, a deadly alien microbe hitches a ride to Earth aboard a downed military satellite and scientists must race to contain it. While fictional, the plot explores a very real and longstanding concern shared by NASA and world governments: that spacefaring humans, or our robotic emissaries, may unwittingly contaminate Earth with extraterrestrial life or else biologically pollute other planets we visit.

It’s an old fear that’s taken on a new relevance in the era of COVID-19, said Scott Hubbard, an adjunct professor of aeronautics and astronautics at Stanford University.

“I have heard from some colleagues in the human spaceflight area that they can see how, in the current environment, the general public could become more concerned about bringing back some alien microbe, virus or contamination,” said Hubbard, who is also the former director of NASA Ames and the first Mars program director.

Hubbard is a co-author of a new report  published last month by the National Academies of Sciences, Engineering and Medicine that reviews recent findings and recommendations related to “planetary protection” or “planetary quarantine” — the safeguarding of Earth and other worlds from biological cross-contamination.

Hubbard discusses several related issues with Stanford News’s Ker Than: the long history of planetary protection, the dilemma posed by Elon Musk launching a Tesla Roadster into space, and the precautions in place to guard against contamination by NASA’s upcoming Mars Sample Return mission, which is scheduled to kick off this summer with the launch of the space agency’s Perseverance Rover.

Ker Than: Concerns about planetary protection date back to the earliest years of the Space Age. Can you briefly explain what the term means?
Scott Hubbard: Even before Sputnik, there were scientific meetings that discussed the potential for space exploration to a) carry earthly microbes to other worlds, thereby confusing or contaminating future scientific investigations, or b) return alien life to Earth and thus possibly threaten our own biosphere. The former issue is called “forward contamination” and the latter is defined as “back or backward contamination.” These concepts were codified in the Outer Space Treaty (OST) of 1967, which has been signed by over 120 countries, including the U.S.