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 "" or "planetary quarantine"—the safeguarding of Earth and other worlds from biological cross-contamination.

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