Why the recent Mars rover landing is unique

The benefits of Terrain Relative Navigation

NASA’s Perseverance rover successfully landed on the Jezero Crater only a couple of months ago on 18 February. While of course each successful Mars rover is significant, the Mars 2020 mission was especially so; landing in the Jezero Crater would have been inconceivable for previous Mars rovers.

Scientists believe that the Jezero Crater, being the site of an ancient river delta, was once filled with water. Therefore, it’s the ideal place for a rover to gain insight into Mars’ watery past and look for signs of past life. On the other hand, its boulders, cliff edges, and sand traps made it less than ideal, and previously it simply was not a reliable enough choice. To combat these challenges, Mars 2020 employs a system called Terrain Relative Navigation (TRN).

TRN is an autonomous, vision-based system, which matches images taken by orbiters to images taken by the rover as it descends. Once enough matches are made between these two sources of data, it is possible to figure out where the rover is relative to a map. Without TRN, the probability of landing safely at the Jezero Crater is about 80-85%; with TRN, the probability of success is brought up to 99%! An article on the BBC described the landing as ‘flawless’.

Another benefit of TRN is that it takes only an hour from touchdown to identify where the rover is on the Martian surface; for previous missions, this has taken a couple of days. This too, is brilliant for the mission and means plans can be carried out straight away. Mars 2020’s plans include searching for signs of past life, and the rover will collect rock and soil samples to send back to Earth. The plan is for the rover to spend one Mars year (about two Earth years) exploring the landing site region.

Almost all future missions (which land on bodies) could also benefit from Terrain Relative Navigation. Comets and asteroids have rough terrain that was previously extremely challenging to land on. The Moon’s polar regions are hard to target but are desirable landing points due to their ability to provide near-constant solar energy. Jupiter’s moon Europa and Saturn’s moon Enceladus both contain fissures coming from subsurface oceans which would also be desirable to explore.

The future of space exploration has truly widened with the pioneering use of this mission’s landing system.

Anika V