NASA engineers have completed a successful separation test of the Mars 2020 rover and its descent stage that will deliver it to the surface of the Red Planet. The indoor test at the space agency's Jet Propulsion Laboratory (JPL) in Pasadena, California, involved the explosive separation of the rover and descent stage, which was lifted away by a crane.
When the Mars 2020 mission enters the Martian atmosphere in February 2021, the final moments before landing will involve a complex series of events and use a more advanced version of the technology used to land the Curiosity rover in 2012.
When it hits the upper reaches of the atmosphere at hypersonic speeds, it will be protected by an aerodynamic heat shield and backshell that will not only ward off the heat of entry as it slows down but will also provide it with some lift, allowing it to maneuver. When it is reduced to supersonic speeds, a series of parachutes will slow it down even more.
After the spacecraft has jettisoned its cruise stage and heat shield, at an altitude of 1 mile (1.6 km), the lander will be traveling at only 170 mph (274 km/h). At this point, the rover and its connected descent stage will drop away from the backshell in a state of free fall.
Shortly after, the eight retrorockets on the descent stage will fire. This will not only allow the craft to slow down for a safe landing but will also use its Terrain-Relative Navigation (TRN) system to seek out a safe landing spot and maneuver towards it – the first time such technology has been used for a Mars landing.
When the spacecraft is at an altitude of 66 ft (20 m), it will be descending at 1.7 mph (2.7 km/h). This is when the Sky Crane maneuver starts. Explosive bolts will detonate, separating the rover from the descent stage – which is the key point that NASA tested at JPL.
After separation, four of the rocket engines shut down as three nylon ropes and an umbilical cord lowers the rover 25 ft (7.5 m) from the descent stage as the lander's wheels deploy to act as its landing undercarriage. As the wheels touch the surface, the ropes and cord are cut by more pyrotechnic units and the descent stage flies off to crash at least 492 ft (150 m) from the landing site.
According to NASA, once the JPL tests of its hardware and computers are completed, including a Surface Thermal Test to simulate the temperatures and pressures of Mars, the rover and the descent stage will ship to Cape Canaveral Air Force Base in Florida for mating with a United Launch Alliance Atlas V rocket in anticipation of its launch on July 2020.
"Firing the pyrotechnic devices that held the rover and descent stage together and then doing the post-test inspection of the two vehicles was an all-day affair," says Ryan van Schilifgaarde, a support engineer for Mars 2020 assembly at JPL. "With this test behind us, the rover and descent stage go their separate ways for a while. Next time they are attached will be at the Cape next spring during final assembly."
Source: NASA
Update (October 9, 2019): This article originally stated the Mars 2020 rover was due to land on Mars in August 2022. The rover is actually scheduled to arrive on Mars in February 2021. The article has been updated to reflect this. We apologize for the error and thank the commenters who pointed it out.