NASA’s Perseverance rover has to face 7 minutes of terror earlier than touchdown on Mars

After “seven minutes of terror” after reaching the upper atmosphere of Mars, NASA’s Perseverance rover is expected to land on the surface of the red planet at 20:55 GMT on February 18. This is incredibly difficult with only about 40% of missions being successful.

As a member of the team that built the European Space Agency’s Rosalind Franklin rover (we have the PanCam, the rover’s camera eyes), which will set off for Mars next year, I’ll be holding my breath during the landing. There is so much at stake. Not only could the mission reveal some of Mars’ best-kept secrets and be an important part of future research into the return of a Mars sample to Earth, but it could also learn important lessons for Rosalind Franklin’s landing.

The appropriately named perseverance soared into the morning sky of Florida on July 30, 2020 with an Atlas V rocket amid a global pandemic for Earthlings. This was the beginning of a nearly 500 Millions of kilometers of driving to the red planet with which Car size Rover and a helicopter called Ingenuity on board.

His destination is the Jezero Crater – a 45 km wide basin with an old, dry river delta, cliffs, dunes and boulder fields – which is being searched for signs of ancient, primitive life on the Martian surface. Of course, it is not impossible for it to find actual life, if there is one. Persistence will also collect samples that another mission will retrieve and return to Earth in the late 2020s. This will be the first attempt to lift off the surface of another planet.

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Landing sequence

The reason it is difficult to land on Mars is because the atmospheric pressure is so low that spaceships move through Mars at tremendous speeds unless they are slowed down. In addition, the landing must take place autonomously and without real-time contact with the earth. The landing sequence for Perseverance is an improved, more precise version of the “Skycrane” technique with which NASA’s Curiosity Rover landed safely in 2012.

The “Seven Minutes of Terror” begins at 8:48 PM GMT when a protective “Aeroshell” with perseverance, ingenuity and a descent vehicle called the “Skycrane” enters the Martian atmosphere at 19,500 km / h. A little more than a minute later, the aeroshell reaches its maximum outside temperature of 1,300 ° C due to the friction with the upper atmosphere. Fortunately, the front of the aeroshell is a heat shield.

At 8:52 p.m., a 21.5 meter parachute is deployed and the heat shield is ejected. Two minutes later, the back part of the shell also separates. The Skycrane, which descends at 2.7 km / h and is powered by eight throttable retro sockets, then lowers the rover onto 7.6 m long nylon cords from a height of around 20 m. When the speed has slowed to 2.5 km / h and the rover hits the surface, the cables will be cut. At 20:55 GMT, persistence should land as Skycrane flies into the sunset at a safe distance.

Entry, descent and landing of the endurance rover. NASA

Although Skycrane has been used before, this time around it has added features known as “Range Trigger” and “Terrain-Relative Navigation” as the landing area is much less flat. The range trigger determines the parachute deployment time based on the rover’s position in relation to the target landing area, which is ten times smaller than Curiosity’s. Terrain Relative Navigation initially uses radar and later live images of the surface to determine the best and most precise landing site within a radius of 600 meters.

Next Steps

Perseverance on the ground can begin its mission. The first 30 “sols” (a sol is a Mars day – 23 hours, 39 minutes and 40 seconds) on Mars are used for initial commissioning, including checking the scientific instruments and short test drives. The next up to 30 sols will be used for test flights of the Ingenuity helicopter. The rover’s surface operations can then begin.

In addition to cameras, radars and other instruments, the rover has a drill that can be used to take samples of stones or earth up to 6 cm long. These are immediately analyzed to look for signs of life, or collected in one of 38 metal tubes for later return to laboratories on Earth. This will be an important step in the study of Mars, as much more detailed analysis can be done in laboratories on Earth. In addition, we know the detailed context of the samples as opposed to the Mars meteorites that we already have.

We are also very much looking forward to the Rosalind Franklin Rover (ExoMars 2022) launch at the next take-off opportunity, currently on September 21, 2022 – with a landing on June 10, 2023. We will closely monitor the landing of Perseverance as we will too used an aeroshell for the descent, along with two parachutes and a retrorocket propelled landing platform called the Kazochok. One of the parachutes has a diameter of 35 m, making it the largest ever sent to Mars.

Rosalind Franklin will be the first to drill up to two meters below the rough, ice-cold Martian surface, which is bombarded by harmful radiation, to take samples from below. If there is life on Mars, it is more likely to survive beneath the surface. The rover will visit an even older location with references to past water, Oxia Planum. These deep samples are analyzed in the rover and the results sent back to Earth.

Some of our PanCam team members and other ExoMars scientists will also be participating in the Perseverance and Hope missions, and we are fortunate to have the opportunity to learn what we can from all of these missions before our own missions – both planetary and also in science. The search for past or even present life on Mars begins in earnest and is a truly international endeavor.The conversation

This article by Andrew Coates, Professor of Physics, Assistant Director (Solar System) at UCL’s Mullard Space Science Laboratory, is republished by The Conversation under a Creative Commons license. Read the original article.

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