After a 203-day journey covering 472 million kilometers (293 million miles), NASA's Perseverance rover successfully landed on Mars on February 18, 2021. Perseverance is the largest and most sophisticated machine to ever land on another world. Building on a long history of Martian surface exploration by rovers and landers, Perseverance will carry out many geological and astrobiological investigations over its initial two-year mission in Jezero Crater. Missions planners chose Jezero because the region possesses geological features strongly suggestive of an ancient lakebed and river delta—prime locations for the potential development of alien life deep in Mars' past, when the planet is theorized to have been warm, wet, and supportive of biology. See also: Astrobiology; Biology; Complex organic materials discovered on Mars; Lake; Mars; Planet; Water
Perseverance shares many design features with Curiosity, the last rover to have reached Mars in 2012. Both rovers are about the size of a small car, although at 1,026 kg (2,263 lbs), Perseverance outweighs its predecessor by more than a hundred kg (220 lbs) and has a chassis that is 12 cm (5 in) longer. Because of the rovers’ record-setting mass, engineers had to innovatively address the intense mission phase known as entry, descent, and landing (EDL). This is the period—nicknamed "seven minutes of terror"—during which the spacecraft carrying the rover first hits the Martian atmosphere while traveling at 20,000 kph (approximately 12,500 mph), traverses the atmosphere, and finally alights onto Mars' surface at low, safe speed. Because of the minutes-long communication delay between Earth and Mars, EDL must be completely automated. For Perseverance as well as Curiosity, EDL began with the cruise-stage spacecraft jettisoning a capsule containing the rover. As the capsule plowed through the Martian air, a heat shield protected the capsule's cargo and slowed its velocity considerably, aided by the deployment of a parachute. Then, at an altitude of about two km (1.3 mi), the parachute detached, and the descent stage connected to the rover's top fired its rockets, slowing descent from 320 kph (200 mph) to a mere 2.7 kph (1.7 mph). Finally, at a height of about 20 meters (66 feet) off the ground, a set of cables lowered the rover from the descent stage directly down, and softly, onto the Martian surface. This sky crane procedure has only ever been used on Curiosity and Perseverance and worked just as designed both times. See also: Aeronautical engineering; Robot rover Curiosity lands on Mars
Now safely settled on Mars, Perseverance will undergo several weeks of commissioning to ready its science instruments and key systems for the work ahead. The mission has four science goals, defined as follows by NASA:
- Geology: Study the rocks and landscape at its landing site to reveal the region's history.
- Astrobiology: Determine whether an area of interest was suitable for life, and look for signs of ancient life itself.
- Sample Caching: Find and collect promising samples of Mars rock and soil that could be brought back to Earth in the future.
- Prepare for Humans: Test technologies that would help sustain human presence on Mars someday.
Of further note, Perseverance will also deploy a small rotorcraft, called the Ingenuity Mars Helicopter, that will perform the first powered flight on another world, demonstrating the technological capability for subsequent explorations. Overall, Perseverance is an ambitious project, having delivered the most advanced scientific instruments to another celestial body to date. With any luck, Perseverance might fulfill the decades-long quest to discover evidence that extraterrestrial life once existed on Mars. See also: Helicopter; Uninhabited aerial vehicle (UAV)
