In the summer of 2020, NASA’s Mars 2020 rover will launch from Cape Canaveral and commence its journey towards the Red Planet. Once it arrives on the Martian surface, the rover will begin building on the foundation established by the Opportunity and Curiosity rovers. This will include collecting samples of Martian soil to learn more about the planet’s past and determine if life ever existed there (and still does).
Up until now, though, NASA has been uncertain as to where the rover will be landing. For the past few years, the choice has been narrowed down to three approved sites, with a fourth added earlier this year for good measure. And after three days of intense debate at the recent fourth Landing Site Workshop, scientists from NASA’s Mars Exploration Program held a non-binding vote that has brought them closer to selecting a landing site.
The workshop took place in Glendale, California, from Oct. 16th to 18th, where 150 to 200 people were treated to oral presentations and discussions led by members of the science community and the Mars 2020 project and instrument science teams. At the heart of the workshop was the evaluation of the four possible landing sites.
These sites are known as Columbia Hills, Jezero Crater, Northeast Syrtis, and “Midway”, respectively. Each site was assessed over the three day period for its suitability based on their potential for in-situ science, potential for yielding valuable drill samples that will eventually be returned to Earth, and the level of confidence in the methods used to evaluate the site’s scientific potential.
First, there’s Columbia Hills, which is located inside the 166 km (103 mi) wide Gusev Crater and was visited previously by the Spirit rover. As was stated in the workshop’s final report, this site is considered a valuable research target because of the way hot springs (which could have supported life) are believed to have existed here at one time.
The Jezero Crater site, meanwhile, is thought to have been the site of an ancient lake which existed during the Noachian or Early Hesperian times on Mars (ca. 4.1 to 3.7 billion years ago). This is due to the preserved river delta that extends into the crater and the nearby outcroppings of exposed clay minerals. These outcroppings are considered to be a likely place to find preserved organics and other biogenic signatures.
The Northeast Syrtis and Midway sites are considered promising because they are connected and virtually identical in composition. Basically, both sites are a stretch of ancient crust that could have been formed by underground mineral springs. What’s more, both appear to have been altered over time by the presence of water.
Each of these sites were evaluated as a primary landing site and as an area for an extended mission after the primary mission was complete. After careful evaluation, and with 158 votes tallied, the Jezero crater site was assessed the highest (or close to) for all criteria relative to both the prime and extended missions. The Midway and NE Syrtis sites were also assessed highly for all criteria for the prime and extended mission, but slightly below Jezero.
Another interesting fact was how Jezero and Midway appeared to be favored for a potential pairing as part of the rover’s extended mission. As is stated in the final letter:
“Interestingly, the Midway and Jezero crater sites were assessed the highest (and received the most votes for high potential) with respect to extended mission criteria, perhaps reflecting the interest in possible extended mission opportunities between the two sites.”
The final decision, based on the overall assessments, will be made by the Mars 2020 team and Thomas Zurbuchen, the Associate Administrator for the Science Mission Directorate at NASA. In the end, all four sites are in keeping with the goals of the Mars 2020 rover, which is not only to look for signs of past (and possibly present) habitability on Mars, but also determine how it evolved since.
The mission will also pave the way for eventual crewed missions to Mars. In addition to retrieving the first samples of Martian rock that will be brought back to Earth for analysis, the rover will attempt to identify sources of subsurface water, improve landing techniques, and characterize the environmental conditions on Mars (including weather, dust, radiation and precipitation).
All of this will play a vital role when it comes to the future, where astronauts could be living and working on Mars for extended periods of time.