Enough meteorites have flown between here and Mars to open the possibility that we’ll find our own relatives up there.
On Earth, living things hang on everywhere there’s liquid water — from scorching hot springs to rocks deep underground. Neither salt nor acid, nor heat, darkness or cold, can kill off all life once it gets started. What does look deadly is lack of liquid water, and until recently this looked to be in short supply on Mars.
And so scientists were cautiously thrilled last month when the journal Science reported that a radar experiment aboard the Mars Express spacecraft detected what looks like an underground lake on Mars. The craft, which was launched by the European Space Agency, arrived in orbit around Mars in 2003.
The apparent lake — its existence needs to be confirmed — stretches about 25 miles across and lies about a mile underground near the Martian south pole. It looks to be between three and six feet deep. There would be no light down there, and the water would have to be very salty to keep from freezing, but that wouldn’t necessarily rule out life. Living things have turned up in similar places here on Earth, including a lake that’s half a mile under the surface of Antarctica.
Scientists can’t help getting excited about the possibility of life on Mars, or anywhere beyond Earth. The only kind of life we’ve ever known originated from a common ancestor. Finding life elsewhere would help us understand the nature of life in a new way.
Enough meteorites have flown between here and Mars to open the possibility that we’d find our own relatives up there, but it’s also possible we’d find a new kind of life altogether.
An abundance of geologic and chemical evidence points to the fact that Mars was nice for a brief time, early in its history. There are dry lake and river beds — evidence that liquid water ran over the surface before Mars lost most of its atmosphere and grew cold. There’s water on Mars, but it’s either wafting through the thin atmosphere or frozen in the ice caps and permafrost.
Life arose very early in Earth’s history — almost as soon as our planet cooled off enough to be habitable. So it’s not unreasonable to think that something similar happened on Mars. If life did emerge on Mars, it might have died off completely. But then, if even a few underground lakes hold liquid water, it might be eking out a living down there to this day. The Antarctic lake organisms, a class called chemoautotrophs, live off the grid, subsisting on chemical energy rather than on the usual sunlight-based food chain. Life is nothing if not adaptable.
There are no immediate plans to visit the lake, though NASA has a sample return mission planned for launch in a few years. Last week, the National Academies of Science, Engineering and Medicine issued a report on planetary science goals, urging NASA to do more to explore our neighboring planet and investigate its prospects for life.- Bloomberg