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12 minutes engine1/10/2023 Skycrane ManeuverĪs the descent stage levels out and slows to its final descent speed of about 1.7 miles per hour (2.7 kilometers per hour), it initiates the “skycrane” maneuver. The direction of its divert maneuver is determined by the safe target selected by the computer that runs Terrain-Relative Navigation. The descent stage quickly diverts to one side or the other, to avoid being impacted by the parachute and backshell coming down behind it. Powered Descent for Perseverance (Illustration): NASA’s Perseverance rover fires up its descent stage engines as it nears the Martian surface in this illustration. Once it’s about 6,900 feet (2,100 meters) above the surface, the rover separates from the backshell, and fires up the descent stage engines. Think of it as a kind of jetpack with eight engines pointed down at the ground. To get to its safe touchdown speed, Perseverance must cut itself free of the parachute, and ride the rest of the way down using rockets.ĭirectly above the rover, inside the backshell, is the rocket-powered descent stage. In the thin Martian atmosphere, the parachute is only able to slow the vehicle to about 200 miles per hour (320 kilometers per hour). If Perseverance can tell that it’s headed for more hazardous terrain, it picks the safest spot it can reach and gets ready for the next dramatic step. Mission team members have mapped in advance the safest areas of the landing zone. Using a special camera to quickly identify features on the surface, the rover compares these to an onboard map to determine exactly where it’s heading. Meanwhile, another new EDL technology – Terrain-Relative Navigation – kicks in. Its landing radar bounces signals of the surface to figure out its altitude. The rover is exposed to the atmosphere of Mars for the first time, and key cameras and instruments can begin to lock onto the fast-approaching surface below. Twenty seconds after parachute deployment, the heat shield separates and drops away. The parachute, which is 70.5 feet (21.5 meters) in diameter, deploys about 240 seconds after entry, at an altitude of about 7 miles (11 kilometers) and a velocity of about 940 mph (1,512 kph). Testing Perseverance’s Parachute: The enormous supersonic parachute for the Mars 2020 mission undergoes testing at the world’s largest wind tunnel at NASA’s Ames Research Center. To nail the timing of this critical event, Perseverance uses a new technology – Range Trigger – to calculate its distance to the landing target and open the parachute at the ideal time to hit its mark. At that point, it’s safe to deploy the supersonic parachute. The heat shield slows the spacecraft to under 1,000 miles per hour (1,600 kilometers per hour). This “guided entry” technique helps the spacecraft stay on the path to its downrange target. To compensate, it fires small thrusters on its backshell that adjust its angle and direction of lift. Full image and caption ›Īs it begins to descend through the atmosphere, the spacecraft encounters pockets of air that are more or less dense, which can nudge it off course. Perseverance Rover Decelerating in the Martian Atmosphere (Illustration): In this illustration of its descent to Mars, the spacecraft containing NASA’s Perseverance rover slows down using the drag generated by its motion in the Martian atmosphere. Safe in the aeroshell, however, the rover gets up to only about room temperature. Peak heating occurs about 80 seconds after atmospheric entry, when the temperature at the external surface of the heat shield reaches about 2,370 degrees Fahrenheit (about 1,300 degrees Celsius). Atmospheric EntryĪs the spacecraft enters the Martian atmosphere, the drag produced drastically slows it down – but these forces also heat it up dramatically. Before entering the atmosphere, the vehicle fires small thrusters on the backshell to reorient itself and make sure the heat shield is facing forward for what comes next. Only the protective aeroshell – with rover and descent stage inside – makes the trip to the surface. Ten minutes before entering the atmosphere, the spacecraft sheds its cruise stage, which houses solar panels, radios, and fuel tanks used during its flight to Mars. Download image › | Metric version › How the Landing Plays Out Final Preparations Perseverance Rover's Entry, Descent and Landing Profile: This illustration shows the events that occur in the final minutes of the nearly seven-month journey that NASA’s Perseverance rover takes to Mars.
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