After more than four years of debate, an ancient crater lake emerged as the top landing spot for the Mars 2020 rover.
Slated to launch in July, the Mars 2020 rover mission will touch down at the Jezero Crater as NASA’s exploration of the Red Planet enters its next phase.
The announcement came Monday, November 19th, after a five-year selection process that considered over 60 candidate locations scattered across Mars. As with every landing selection, there's an ongoing tension between choosing a safe location for landing versus a location that is scientifically rewarding to visit in the first place.
Nasa believes the rocks in this nearly 50km-wide bowl could conceivably hold a record of ancient life on the planet. It is the kind of environment that might just have supported microbes some 3.5-3.9 billion years ago.This was a period when Mars was much warmer and wetter than it is today.
The site offers geologically rich terrain with landforms reaching as far back as 3.6 billion years, and could potentially answer important questions in planetary evolution and astrobiology. Satellite images of Jezero point to river water having once cut through its rim and flowed via a delta system into a big lake.
Unlike most Mars rovers and landers of prior decades, the 2020 robot’s mission will be to not only find hints of warm, watery conditions in the past, but to also set up the search for life itself. It will do this by collecting and caching samples of Mars rocks for a future spacecraft to retrieve and return to Earth, and it will sniff around for the distinctive signatures of biology in the rocks it encounters.
Mars 2020 marks the first time NASA has gotten serious about bringing back samples of Mars rocks. And although that plan will ultimately involve billions more dollars and at least one other spacecraft, scientists are taking the challenge seriously. Nasa is working with the European Space Agency (Esa) on a possible robotic sample return mission, but exactly when the sample tubes might come home is uncertain.
Why Jezero Crater?
Stretching 30 miles across and 1,600 feet deep, Jezero is the site of an ancient crater lake (its name means “lake” in Serbian) that was replenished by rivers depositing water and sediments into the basin.
Red marks the location of Jezero Crater on the surface of Mars relative to the location of other missions (yellow) and geological sites (white). NASA / JPL / additions by author
Located near latitude 19°N and longitude 77.5°E in the Syrtis Major region, the 30.4-mile-diameter (49-kilometer) Jezero Crater appears to have once been flooded with water early in the history of Mars, and contains many promising geological targets for the rover, including at least five varieties of rock as well as an assortment of carbonates and clays. These are crucial for the mission, as the Mars 2020 Rover will specifically look for signs of life past and present on Mars. The crater seems to also have been a watershed for a nearby flowing delta fan, which might have carried nearby material into the crater.
But the crater will also be a challenging place for the Mars 2020 Rover to land and operate. The crater is littered with smaller impact craters and large boulders. There are also depressions filled with wind-driven sand, spots that could act as sand traps for a rover.
Building on tried and test technology
The 2020 rover is based on the one-tonne Curiosity robot that the agency landed in Gale Crater in 2012. Curiosity has been a great success, and NASA wants to repeat it. Using the same "template" also saves money; some equipment spares were left over from 2012.
That said, instrument-wise, the new vehicle is quite a bit different. Yes, it will again feature cameras, a robotic arm, a drill and a laser - but there is a new suite of sensors and analysis tools, and there is even an experiment to demonstrate how future astronauts might make oxygen on the Red Planet.
The Mars 2020 Rover will land using the same "sky-crane" descent technique pioneered by the Mars Curiosity Rover, which successfully landed in Gale Crater on August 6, 2012. Since then, researchers have gotten much better at predicting where the lander will end up, shrinking the targeted landing area for the Mars 2020 Rover down from half that of Curiosity's. Unlike Curiosity, the Mars 2020 Rover will employ a new landing capability known as Terrain Relative Navigation (TRN), which will allow the rover to autonomously analyse the landing site and maneuver to avoid hazardous areas during descent. The ASPIRE suborbital launches out of NASA Wallops in Virginia also completed testing of the descent parachute for the mission this past summer.
The site selection isn't finalised yet, however. Now, the Jezero Crater selection is dependent on analysis and verification testing of the TRN capability. NASA's Mars Reconnaissance Orbiter will also now map the terrain at Jezero Crater in greater detail. A final report on the site made by an independent review board is due in the 3rd quarter of 2019 to NASA Headquarters.
The 2020 venture will leave Earth in the July/August of that year and should land on 18 February 2021.