Largest planetary rover

The largest planetary exploration rover is Perseverance, built for NASA by the Jet Propulsion Laboratory in Pasadena, California. Perseverance is built to the same basic design as its sibling Curiosity but includes additional scientific equipment and a ride-along experimental helicopter, as well as mechanical upgrades (such as stronger wheels), which make it significantly heavier. Perseverance has a mass of 1,026.4 kg (2,262.8 lb), compared to Curiosity's 900-kg (1,984 lb). The Perseverance rover touched down in the Jezero Crater on 18 February 2020.

Work started on Perseverance (formerly known as the Mars 2020 Rover) in 2012, not long after Curiosity successfully touched down on the surface of Mars. The rover's design is based on that of its predecessor, but with a different payload of scientific instruments and upgrades to certain mechanical and electronic components. The most important upgrades over Curiosity's design are the larger, stronger wheels (Curiosity's have sustained more severe damage than expected), a higher quality main camera array (Supercam) and improvements to the onboard computer system that will allow the rover to handle more tasks simultaneously (such as operating instruments while moving).

The rover's instruments are named using a variety of contrived backronyms (as has become NASA tradition) and include PIXL (Planetary Instrument for X-Ray Lithochemistry), a spectrometer designed to reveal the elemental composition of surface materials; MOXIE (Mars Oxygen ISRU Experiment), which is to test a technique for generating oxygen from Mars's CO2-rich atmosphere; and SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals), another spectrometer, this time set up to look for traces of organic compounds.

The most significant new piece of equipment on Perseverance are the sample return tubes and the systems that go with them. These ultra-clean test tubes are designed to form the first step in a long and complex undertaking called the Mars Sample Return (MSR) mission. As it travels, Perseverance will fill these tubes with samples, seal them up, and leave them in caches on the Martian surface. The mechanism used to accomplish this is astoundingly intricate and complex, even by JPL's standards, and includes a second robotic arm in the underside of the rover body. The plan is to retrieve these samples using a second mission that would send a lander with a sample return rocket and a "fetch rover" to go and collect the tubes dropped by Perseverance.

The Jezero Crater is a 45-km-wide (28-mile) basin in Mars's northern hemisphere. It was chosen as the landing site based on many years of observations by the Mars Reconnaissance Orbiter and other Martian satellites, which revealed evidence of a 3.5-billion-year-old river delta and lake. Though any trace of this surface water has long since vanished, scientists believe this location gives Perseverance the best possible chance of finding fossil evidence of microbial life – a long-term goal of NASA's Mars exploration program.