Køretøjet Perseverance, som det vil se ud, når det er landet på Mars. Kamerasystemet fra DTU Space indgår i instrumentet PIXL – som på illustrationen lyser med violet mod klippen. (Illustration: NASA)

‘Seven minutes of terror’ before landing on Mars

Wednesday 17 Feb 21


John Leif Jørgensen
Professor and Head of Measurement and Instrumentation
DTU Space
+45 45 25 34 48


David Arge Klevang Pedersen
Associate Professor
DTU Space
+45 45 25 36 09

The hunt for signs of past life

The equipment that DTU Space supplied to the Mars 2020 mission consists of a micro-context camera and a floodlight system, as well as a computer that processes data from the camera system.

It is part of the planetary instrument for X-ray lithochemistry (PIXL), which will scan and examine selected rocks on Mars for signs of life. The DTU equipment is intended to position PIXL precisely at the cliffs that are to be examined, and take pictures and map the colours and contrasts in the rocks.

Among other things, PIXL will analyse the chemistry of the surface. This may reveal possible signs of biological fossil material in the rocks.

NASA’s Mars mission, which DTU Space is participating in, has to be slowed down from 20,000 kilometres per hour to walking pace, and find the right place to land before the craft is lowered onto Mars. This must happen within seven minutes on 18 February 2021.

At DTU Space, researchers and experts are looking forward with excitement to 10 pm on February 18. That is when years of work will culminate in NASA’s Mars 2020 mission landing on the surface of the red planet. DTU Space has supplied an advanced camera system for the vehicle Perseverance, which in the coming years will look for past signs of life on Mars.

When the landing begins, DTU researchers will be glued to their screens watching the NASA control room.

“The Mars 2020 landing will be a big event for us, and we’re very excited. If we land as planned, we have a very exciting mission ahead of us. So far everything is going according to plan,” says John Leif Jørgensen, professor at DTU Space, who is in charge of DTU Space’s contribution to the mission.

Seven nerve-racking minutes

The DTU camera system and the rest of the equipment on the mission will go through what the experts call ‘seven minutes of terror’. This will be the time from when the craft enters the Martian atmosphere until it lands safely within a relatively small target area on the planet’s surface. It will be a nerve-racking wait.

“As they say at NASA, ‘We’re coming in hot’. The spacecraft will be moving towards Mars at a speed of 20,000 kilometres per hour. But because Mars simultaneously moves around the sun at almost the same speed, the speed relative to Mars locally is about 9,000 kilometres per hour. And that will also be the speed at which we’ll enter the upper part of Mars’ atmosphere. From there it has to be slowed down to ‘pedestrian pace’ for a safe landing,” says John Leif Jørgensen.

And it’s a challenge to get into orbit and land precisely on Mars at the same time:

“Only about 40 per cent of all Mars missions have been successful,” says NASA ahead of the landing. Perseverance is only the fifth vehicle they will attempt to land on Mars.

The difficulty of the current mission is that many things have to work perfectly in sequence to achieve a safe landing, and this must be done without help from Earth, since Mars is so far from Earth that, during the landing, the light—and thus radio waves for communication—will take more than 11 minutes to arrive.

500 million kilometres

"The camera from DTU Space will take pictures of the surface on Mars. So if there are signs of life, our equipment will capture images of it."
Professor John Leif Jørgsensen, DTU Space

When the craft carrying Perseverance reaches Mars, the equipment will have travelled nearly 500 million kilometres since the mission was launched from Cape Canaveral in the US on 30 July last year.

This is one of NASA’s biggest missions, with a budget in the region of DKK 13 billion (USD 2 billion). Years of development, design, construction, and testing have gone into the project at DTU in Denmark and NASA and other partners in the US.

“This landing will be the preliminary culmination of many years of work here at DTU. We’re proud to have provided equipment that meets NASA’s extremely stringent quality and performance requirements,” says John Leif Jørgensen.

“Among other things, the camera from DTU Space will take pictures of the surface on Mars. So if there are signs of life, our equipment will capture images of it.”

Space technology with many uses

Equipment based on advanced development of DTU’s star camera technology is also being used for many other purposes by both NASA and ESA.

For example, it’s used for precise navigation of satellites, which from orbits near the Earth measure the thickness of ocean ice, sea levels, the melting of ice from Greenland, and the amount of moisture in the global ecosystem. The camera system has also been used to capture images of dust particles in space and explore them further.

By contributing to space missions with the development of advanced technology—which are subject to strict quality requirements—and sharing its knowledge and systems with other research areas, such as Earth observation, DTU helps ensure that society benefits from the best new technologies.

The landing on Mars is a story in itself

The spacecraft with the Mars vehicle Perseverance on board must be slowed down from about 20,000 km per hour in space to a normal walking pace when it reaches the surface of Mars.

Along the way, it has to descend through Mars’ thin atmosphere using a parachute before a braking rocket system slows it down and the vehicle is released and gently lowered to the surface.

On the way down, even without intervention from the Earth, the control system can change direction and find an optimal landing site if it detects problems at the selected landing site in the Jezero crater on Mars via sensor systems. (Animation: NASA)