Why Earth’s Spores Could Survive A Trip to Mars

Here’s a finding to give planetary protectionists pause: two species of spores mounted on the International Space Station’s hull a few years back showed a high survival rate after 18 months in space.

Providing that they are shielded against solar radiation, it appears the spores are quite hardy and could easily transport on a spacecraft headed for Mars — which is concerning since so many scientific investigations there these days are focused on habitability of Martian life (whether past or present). The experiment was published in 2012, but highlighted in a recent NASA press release about planetary protection.

The experiment was called PROTECT (an acronym of Resistance of spacecraft isolates to outer space for planetary protection purposes) and studied spores of Bacillus subtilis 168 and Bacillus pumilus SAFR-032. B. pumilus spores were found in an air lock between a “clean room” and entrance floor at NASA’s Jet Propulsion Laboratory, and in previous studies were shown to be more resistant to UV radiation and hydrogen peroxide than “wild” strains. B. subtilis is a spore that has been studied in other space environment experiments.

Samples of both spores were mounted on the EXPOSE-E facility on the space station, which provides up to two years of space exposure. The major goal of this European Space Agency experiment is to study “the origin, evolution and distribution of life in the universe,” NASA states, adding that anything mounted outside of there has to survive “cosmic radiation, vacuum, full-spectrum solar light including UV-C, freezing/thawing cycles [and] microgravity.”

The European Technology Exposure Facility (EuTEF) attached to the Columbus module of the International Space Station. Credit: DLR, Institute of Aerospace Medicine/Dr. Gerda Horneck

The experiment found that if the spores were in areas replete with solar UV radiation, most of them were killed. If those rays were filtered out, however, the spores showed a 50 percent survival rate on both space and simulated “Mars” conditions. It is most concerning to scientists when considering a situation where spores could be hiding underneath each other during a spacecraft trip. The ones on the outside would likely die, but the ones on the inside — shielded from solar radiation — could make it there.

One key limitation in this study, however, is that only two types of spores were studied. This does present a case for doing more studies on this matter in the future, however. Space agencies are quite aware of the problem of planetary protection, as evidenced by departments such as NASA’s Office of Planetary Protection and ESA’s Planetary Protection Officer.

Spacecraft designers constantly make decisions to keep the extraterrestrial bodies we study as safe from Earth contamination as possible; one famous example was when the Galileo probe was deliberately sent into Jupiter in 2003 to protect Europa and other potentially life-bearing moons of the giant planet from possible contamination.

Images of Bacillus pumilus SAFR-032 spores (seen in an electron micrograph) on aluminum before and after being exposed to space on an International Space Station experiment. Credit: P. Vaishampayan, et al./Astrobiology

You can read the entire study (led by DLR’s Gerda Horneck) in Astrobiology. Also note that there are two other EXPOSE-E studies published around the same time: “Survival of Rock-Colonizing Organisms After 1.5 Years in Outer Space” and “Survival of Bacillus pumilus Spores for a Prolonged Period of Time in Real Space Conditions.”

The rock study (led by Tuscia University’s Silvano Onofri) takes the question of the spores in a different direction, which is examining the phenomenon of “lithopanspermia” — how organisms might move between planets (say, on a meteor). Since Mars meteorites have been found on Earth, some researchers have wondered if life could have spread between our two planets. If that were to happen, the researchers cautioned, the spores would have to survive for thousands or millions of years.

The other B. pumilus paper (led by NASA’s Parag A. Vaishampayan) noted that those spores mounted outside of the space station that survived, showed higher concentrations of proteins that could be linked to resisting UV radiation.

Elizabeth Howell

Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.

Recent Posts

Why ‘Contact’ still resonates after 25 years

25 years ago, the film Contact made its theatrical debut starring Jodie Foster and Matthew…

13 hours ago

The First SLS Launch Caused Damage to the Launch Pad. How bad was it?

When you test launch the most powerful rocket ever successfully flown, there’s bound to be…

14 hours ago

What Happened to those CubeSats that were Launched with Artemis I?

The Artemis I mission deployed ten CubeSat's as part of its mission, but only four…

16 hours ago

If We’re Going to Get Under the Ice on Europa, How Will We Send a Signal Back to the Surface?

If we send some type of nuclear-powered tunnelbot to Europa to seek life under its…

22 hours ago

Mars Once had Enough Water for a Planet-Wide Ocean 300 Meters Deep

New research has shown that Mars may have been covered in a worldwide ocean when…

22 hours ago

What’s the Best Mix of Oceans to Land for a Habitable Planet?

Earth is about 29% land and 71% oceans. How significant is that mix for habitability?…

2 days ago