Tardigrades, commonly known as water bears, may be better suited by a new name: Tardiguardians of the Galaxy. Unlike the fictional ragtag team of unenthusiastic heroes, the microscopic animals are providing real insight into how humans could adapt extraterrestrial resources to support space exploration, as well as whether such resources could help protect against the Earthly contaminants that humans might shed.
Co-led by Penn State Altoona Professor of Microbiology Corien Bakermans, an international research team recently found that tardigrade activity - a key indicator of their health - was significantly reduced when they were placed in simulated Martian regolith. That's the loose mineral deposits covering a planet's or moon's bedrock, similar to soil on Earth. However, simply washing the regolith with water prior to introducing the tardigrades appeared to remove some harmful element and mostly mitigate the impact on their activity. The findings, published in International Journal of Astrobiology, are a small step towards a giant leap for humanity, according to Bakermans.
"When considering sending people to non-Earth environments, we need to understand two things: how the environment will impact the people and how the people will impact the environment," said Bakermans, who coordinates the Penn State Altoona's biology program. "With this research, we're looking at a potential resource for being able to grow plants as part of establishing a healthy community - but we're also looking at whether there are any inherent damaging conditions in the regolith that could help protect against contamination from Earth, which is a goal of planetary protection."
Planetary protection refers to keeping extraterrestrial bodies safe from Earth contaminants and vice versa. It also strives to keep the science enabled by space exploration - whether by humans or robot - as free of contaminants as possible. The practice was agreed upon by multiple countries and is regulated by several space agencies, including NASA.
In other words, Bakermans said, if a planet contains its own defense mechanism for extraterrestrial invaders in the regolith covering its surface, then that may be one less concern for those planning space missions. However, such a mechanism would likely mean that humans hoping to establish a base would be unable to adapt the regolith to support their needs, like growing food. If the defense were strong enough, it could also directly harm humans.
"We know a lot about bacteria and fungi in simulated regolith, but very little about how they impact animals - even microscopic animals, like tardigrades," Bakermans said, explaining that simulated regolith is designed to precisely mimic the mineral and chemical composition of what's available on Mars' surface. "We investigated the specific, isolated impact of the regolith on tardigrades."
