It’s Time to Protect Ourselves From Space Germs

As missions take us deeper into space, are we prepared for what we might bring back?

With eyes as starry as the skies, we look to space and wonder, “Are we alone?” It’s a very human question, one that’s based in science as well as philosophy, fiction, and fantasy. It’s also a question we may soon have the answer to. Space agencies around the world are gearing up to travel ever deeper into space to Jupiter’s moon of Europa, which are considered within habitable zones since water can exist in liquid form. If there is life out there, these missions may well find it.

But it’s not enough just to find life. We intend to study it, too. The plan is to bring back samples from habitable zones to test for, among other things, signs of extraterrestrial life — paying particular attention to any negative impact on the Earth. Space agencies NASA and ESA (the European Space Agency) have united to launch a Mars Sample Return mission from 2020 to 2030. Within the next decade, we may get a chance to meet our cosmic neighbors.

It’s an exciting prospect, but it’s also terrifying. The 2018 Marvel film Venom paints a frightening picture of a sample return mission gone wrong. A malfunctioning spacecraft crash lands on re-entry, and a breached container unleashes malevolent, human-munching life forms. As extraordinary (and unlikely) as this fictional scenario seems, there are real-world policies in place to protect against such events.

How can we protect against all eventualities?

The 1967 Outer Space Treaty (OST) marked a commitment to the peaceful exploration of space. Under the watchful eye of the United Nations Office for Outer Space Affairs (UNOOSA), parties to the Treaty are bound by international law to abide by the principles of peaceful exploration. And Article IX of the Treaty stipulates that space explorers should take responsibility for protecting the solar system from biological interchange. Space exploration risks transporting terrestrial organisms from Earth to celestial bodies, known as forward contamination. Likewise, returning missions risk backward contamination, bringing home extraterrestrial organisms that may have harmful effects on Earth. The concept of planetary protection was born.

UNOOSA appointed the Committee on Space Research (COSPAR) to develop a planetary protection policy. The policy ensures that space agencies (and potentially private companies like SpaceX) have non-legally binding guidelines for designing missions with the risks of contamination in mind. Mission plans are reviewed and assigned a category from I to V. Sample return missions from habitable zones are classified as Category V: restricted Earth return.

Japanese space agency JAXA received initial categories for the MMX sample return mission to Phobos and Deimos, the Martian moons. For the outbound journey launching in 2024, COSPAR assigned planetary protection Category III. This category concerns flyby and orbiter missions where the risk of contamination is high and the target body is of interest due to chemical evolution and/or origin of life.

COSPAR classified the return journey as Category V: unrestricted return to Earth since the moon sample is unlikely to contain life. These categories help space agencies design or alter missions to minimize the risk of biological interchange.


2004, scientists stood in the scorching Utah desert, awaiting the spoils of the Genesis space probe mission. In an undignified crash-landing, the broken containers were hastily scooped up and carted off for testing. Luckily, the containers held the remnants of solar winds and not samples housing extraterrestrial life. But incidents like this make people nervous. How can we protect against all eventualities?

We can’t. COSPAR’s Planetary Protection Panel admits that there are many questions still to be answered and much work to be done before backward contamination is confidently addressed. As yet, the high-tech facilities needed for biohazard and life detection don’t exist. The Johnson Space Center in Houston currently receives lunar and asteroid samples for testing. But it doesn’t have the necessary capacity to carry out the full biohazard and life detection processes for samples from habitable zones.

“There is no absolutely optimal approach to decontamination under these circumstances…”

According to NASA’s 2002 Draft Test Protocol for Detecting Possible Biohazards in Martian Samples Returned to Earth, we’ll need to design, build, and test a specialized Sample Receiving Facility (SRF) well in advance of sample returns. Ideally, the SRF will start to be designed and built 10 years before the return of samples from habitable zones.

Should samples reach Earth without incident and be secured in an appropriate facility, there’s still the pesky question (and ethical implication) of how to sterilize and neutralize “life not as we know it.” Scientists acknowledge that life on Mars may not take a carbon-based form. In fact, Martian life forms may be beyond our comprehension, which is something scientists are struggling to prepare for.

At best, NASA predicts (in the Draft Test Protocol) that “bond breakage by heat or gamma radiation should be similar for Earth and Mars life forms, and sterilization conditions for Earth microorganisms should eradicate microorganisms of similar size from Mars.” This sounds promising. However, “there is no absolutely optimal approach to decontamination under these circumstances, but enough is known about the relationships among organism size, repair mechanisms, and survivability, that the maximum survivability of any martian organisms can be estimated with some confidence.”

Whether the public will be happy with phrases such as “no optimal approach,” “estimated,” and “some confidence” is another matter.

Photo: Dimitri Gerondidakis/NASA
Photo: Dimitri Gerondidakis/NASA

Planned missions taking us deeper into the solar system are expected to yield significant scientific rewards. NASA’s New Frontiers Program has planned several missions to explore the solar system and return samples. The OSIRIS-REx mission and the NASA-funded CAESAR mission will be collecting samples from an asteroid and comet respectively. Launching in 2024, CAESAR will collect a sample from the comet 67P, returning to Earth by 2038, while the OSIRIS-REx mission originally launched in 2016 is due to return with a sample from the asteroid Bennu in 2020.

But it is the missions to celestial bodies within habitable zones that ignite the imagination. ESA’s JUICE mission set to launch in 2022, and will investigate three of the four Galilean moons. The mission will include flybys of Europa, an icy moon of particular interest due to evidence of oceans and the potential for alien life. NASA is also planning flybys of the icy moon with its Europa Clipper mission, due to launch in 2025 as part of the Solar System Exploration Program.

Over the next decade, the 2020–2030 Mars Sample Return mission will bring us closer to the possibility of contact with extraterrestrial life. NASA has its 10 years to start building a suitable testing facility. And we can hope the hypotheses of scientists are correct so we can protect Earth from alien contamination.

All Rights Reserved for Amie Haven

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