jdilla.xyz

From Why Not Mars by Maciej Cegłowski

"At this point, it is hard to not find life on Earth. Microbes have been discovered living in cloud tops[28], inside nuclear reactor cores[29], and in aerosols high in the stratosphere[30]. Bacteria not only stay viable for years on the space station hull, but sometimes do better out there[31] than inside the spacecraft. Environments long thought to be sterile, like anoxic brines at the bottom of the Mediterranean sea[32], are in fact as rich in microbial life as a gas station hot dog. Even microbes trapped for millions of years in salt crystals[33] or Antarctic ice[34] have shown they can wake up and get back to metabolizing[35] without so much as a cup of coffee."

As Ceglowski points out, this should make us pretty confident that microbial life already exists on Mars, if only from a stray asteroid.