Mars might have its own defense mechanism against life from Earth, in a kind of reverse of "The War of the Worlds" scenario that could help protect the Red Planet from contamination by terrestrial bugs.
Scientists led by Corien Bakermans, a professor of microbiology at Penn State University, were experimenting with exposing tardigrades, which are microscopic animals nicknamed "water bears" that grow to at most half a millimeter in length, to simulants of Martian regolith.
