In two years, NASA will launch a new machine to explore the planet Mars. Now, NASA is finally narrowing down exactly where on Mars it will wander. The agency announced a final short list of three sites from which it will choose the final destination.
It took a while to get here. NASA narrowed the field from 30 possible destinations to 8 back in 2015 before this cut down to the final three. One of the most important objectives of the Mars 2020 rover is to find some evidence of life on Mars. These three sites were chosen because there is strong evidence of water there, both presently and in the past. Rock samples collected there have a good chance of indicating whether the red planet contained life at any point in its history.
Here they are, the final trio of contenders:
Gusev crater is a large area best known as the landing site of the Spirit rover back in 2004. Spirit found evidence that at one point hot springs flowed here, and Gusev crater may have been the site of a shallow lake. If Mars 2020 lands here, it will bring a modern suite of tools to examine this region for signs of life.
Syrtis Major is a formerly volcanic region of Mars, where a large shield volcano sent ash and basalt hundreds of miles in every direction. The northeastern part of this region is especially promising, because the ash and minerals from the volcano mixed with melted ice and hot spring water. This fertile area may have cultivated microbial life, which still could be preserved in the rock.
Jezero crater has a history of alternating between wet and dry cycles. On multiple occasions, water would flow into the crater, forming a lake and bringing clay minerals from the surrounding area. Microbial life could have flourished here, and their remains would still be present in the dry lakebed.