10 years after its launch, the Mars Reconnaissance Orbiter has made an exciting discovery. A dried up lakebed near the equator of Mars has been found, one which would likely contain simple fossilized life if it once existed there.
It has long been known that Mars once contained water. Dried up rivers and lakes have been imaged and minerals have been found in these lakes and rivers that, on Earth, are associated with water. Some rocks on Mars also appear weathered as though water has been flowing over them for millions of years; similar to rocks you would see at the ocean.
Evidence of water being in this area comes from the presence of salt deposits in the basin. On Earth, areas with large salt deposits once had salt water that has evaporated, leaving behind the salt. Some examples of these are the Bonneville Salt Flats in the US and Salar de Uyuni in Bolivia.
The lake found by the Mars Reconnaissance Orbiter is thought to be the most recent area where water was present on the surface of Mars. The researchers estimated that there was water present in the lakebed about 3.6 billion years ago. Using images taken by the orbiter of small channels carved out by water from the lake, they could get an estimate at when water last flowed. These channels were created when water from the lake overflowed. The channels were created by flowing water that ran through areas of volcanic plains that are about 3.6 billion years old so the water can’t have existed earlier than this.
While we are almost certain there was water on Mars at one point, we do not yet know whether there was life. This dried up lakebed would be an ideal place to look for life though as it could be preserved in salt deposits. Organic matter can be preserved quite well in salt so if there was life in this lake, we could likely find it if we sent a rover there. The fact that this water persisted on the surface of Mars much longer than in any other known lake or river on Mars is encouraging for life because it would have had a lot of time to appear.
The salt content of the lake was about 8% of the salinity of Earths oceans so it would have been favourable for life as we know it.
There are currently no plans to send a spacecraft to this area but hopefully this study will change that. The opportunity rover is about 100 miles away from the lake and while this may not seem very far, rovers are not designed to travel more than 30 miles. Furthermore, opportunity is not outfitted with the right tools to detect life.
If there is a mission planned to visit this area, it will be several years in the future but it would very worthwhile. It may be the best way to discover evidence of life beyond Earth.