Why Iceland Is The Closest Thing Scientists Have To Mars

Robot rovers on Mars have recently provided the best evidence of past Martian life to date. In September, NASA announced the discovery of likely biosignatures on the red planet: small leopard-print-like spots that, so far, are only known to form from microbial life. It's kind of like finding a fossil from 140 million miles away. Now, scientists are more eager than ever to explore life on ancient Mars — and what better way to do so than by studying the geology of Iceland?

It's widely accepted that Mars once had a diverse hydrological landscape. That is, water used to flow in rivers, lakes, and streams. The camera on NASA's Curiosity rover has discovered some fascinating things on Mars, including evidence of ancient lakes. But for the most part, the rover has mostly captured images of endless sedimentary rocks and a dry, hostile surface. Such signs indicate a Martian past of flowing water and volcanic activity. After all, without flowing liquid, sediment deposits are simply impossible. As luck would have it, Iceland's geology mimics such ancient Martian conditions perfectly. 

As Mike Thorpe of the NASA Goddard Space Flight Center puts it, Iceland and ancient Mars have geologies that form a "one-to-one" comparison. Iceland's chilly rivers carve basalt canyons, exposing layers of sedimentary rock that originated in volcanoes and were laid down by water flows. The same geological process occurred on Mars, albeit billions of years ago. Now the challenge is to figure out how to read those sedimentary rock layers for signs of life. The team assigned to the task is called SWIFT (Southwest Iceland Field Team), and it's been busy collecting samples from Iceland's southwestern Stóra Laxá region to unearth the ways life survives in a rugged, alien landscape.

By understanding how life works on Earth, we can apply that knowledge to other planets. To achieve this, NASA looks for "planetary analogs," regions on Earth that geologically resemble extraterrestrial landscapes. For example, Meteor Crater in Arizona is studied to understand the impact craters on the moon, while seismometers in Greenland are used to explore the moonquakes of Jupiter's moon Europa.

But finding signs of life on Mars is largely a question of chemistry. Most importantly, it's a search for carbon, the most important element of organic compounds and of life itself. The SWIFT team has collected samples from Iceland's hydrothermal vents, rock walls, river beds, and lakes in their search. The hunt has involved scuba tanks, long hikes, and countless sample containers. According to NASA's video on the endeavor, the lake that the team is focused on, Lake Kleifarvatn, has a similar composition to the lakes that likely existed on Mars some 4 billion years ago. Lake Kleifarvatn is ripe with hydrothermal vents and fine-grain siltstone, which would have been abundant on Mars in the past.

The samples drawn from Stóra Laxá's hold large amounts of carbon dioxide gas, which rises out of the sediments of the lakes. It's easy to draw parallels with the ancient lakes of Mars, and other compounds found there are also likely to have been present in the past Martian landscape. Iceland's geology has both organic and inorganic compounds, as well as minerals that are critical for life. The research is exciting, since it helps build a profile of the conditions of life on Mars. If life can endure the harsh conditions of Iceland, it's not a far stretch to conclude that life could also be able to endure the ancient climate of Mars.