Penelope Boston believes there’s life on Mars. Specifically, she thinks it’s underground. With this in mind, she spends lots of her time exploring caves on earth, including places she tells us are “determined to kill us from the moment we enter them.”
She believes that “life is as common as muck” throughout the universe. This means that when most of the people in the world thought there was no life on Mars, she gave it a few percent chance. After recent exploration of Mars, which shows ice underground, and sedimentary rock, she now believes the chances of life are closer to 1 in 4, possibly 1 in 2. She’s fascinated by a set of rock formations called “blueberries”, which appear to be small accretions of mineral. She’s now got biological systems producing very similar accretions in her lab, suggesting they could be biologically created.
If there’s life on Mars, and if it’s underground, we need to think about some interesting questions: how do we protect that life? How do we protect ourselves from that life?
To explore these questions, she’s investigating extreme biological environments. One is Cueva de Villa Luz in Tabasco, Mexico, an impossibly hostile environment. There are huge levels of hydrogen sulfide in the cave, which means you can’t enter without protective suits and breathing apparatus. The environment is filled with sulfuric acid. But it’s also filled with life, including bacteria that produce sulfuric acid and live in environments with ph 0. The cave is so abundant with life that locals harvest fish from the cave twice a year… something that rarely happens in other underground environments.
Another cave, Lechuguilla Cave, part of the Carlsbad system in New Mexico, has vast walls covered with glistening sheets of metal. These are biominerals, deposited by bacteria that eat rock and deposit metals as waste. There’s the intriguing possibility that bacteria like this could eat toxic metals like uranium and produce less toxic byproducts.
These crazy cave conditions might represent average conditions on other planets. Learning to explore caves with robots – including through crazy ideas like swarming masses of hopping, semi-autonomous robots – might teach us the strategies we’ll need in the future to explore Mars without contaminating life there, or killing all life on earth.