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Niels Bohr Institute > Who, What, When > > Jens Martin Knudsen > nye missioner

23 January 2015

Part 7 – Danish Mars research on new missions

Jens Martin Knudsen (1930-2005) retired in 2000 at the age of 70. But Mars research has continued with Danish participation in the Phoenix mission in 2008, the MSL mission in 2012 and the planning of the next mission, Mars 2020 ...

Even though Jens Martin Knudsen retired in 2000, he remained very active in both the Mars Group and as a lecturer in public.

Jens Martin Knudsen made sure that his 'co-Investigator' role for the Mars Exploration Rovers in 2001 was transferred to Morten Bo Madsen, but Jens Martins Knudsen's interest continued unabated as long as he lived – as did his contribution to the group's work.

Phoenix mission in 2008     

In 2008, the group took part in NASA's so-called 'Phoenix Mission', where the Danish researchers and technicians delivered a set of three reference plates for the colour calibration of the stereo colour cameras on board the mission.

Seen here is one of the three colour reference plates the Niels Bohr Institute delivered for the Phoenix mission that NASA sent to Mars in 2008. To the left is one of the two solar panels unfolded after the landing and to the right is the lander's instrument deck with a colour reference plate located near the corner to the left. The plate is black anodised and is equipped with six powerful ring magnets placed under thin discs of pigmented synthetic rubber. The built-in magnets have the effect that (magnetic) airborne dust is attracted to the ring magnet and the area in the middle of the magnet is kept relatively free of dust. The central area of the disc also remains much cleaner than the surroundings and the effect is used to calibrate the colours and spectra (in the visible and near-infrared wavelength range) for all images taken with the mission's stereo camera.

These colour reference plates were improved in relation to the 'sweep-magnet' experiments that had been carried out on previous missions, in order to investigate the non-magnetic dust that is able to land in the middle of the ring magnets.

The improvement included making the magnets larger – and this made the relatively clean area a little bigger.

The colours of the protected area in the centre of the magnets were also different and the Danish team hoped that this would make it possible to detect the dust that might find its way into the middle of the strong ring magnet.

The experiments with the collection of dust on the colour reference plates showed that the amount of non-magnetic dust is (probably much) less than 30% of the total amount of dust, but since the mission only lasted 150 days on Mars, it was difficult to say anything very precise about the properties of the few particles that landed in the more or less protected area in the middle of the magnets with the available data.

Inspired by the Vikings

A significant part of the Danish involvement in the Phoenix mission was that the Niels Bohr Institute's colleagues in Aarhus supplied an anemometer, called a 'Telltale', for the Phoenix mission.

It is a small and simple instrument that is also very accurate and has given the best wind measurements on Mars to date. The instrument was inspired by the small pieces of wire that were first used by the Vikings in front of the sails on the Viking ships to fine tune the sails to operate with optimum efficiency.

It consisted of a small ultra light tube made out of Kapton and suspended in woven Kevlar fibres in order to provide a little damping so the tube would not swing like a pendulum. Placed under the Kapton tube was a small square mirror, which allowed the images from the mission's stereo camera to observe movement in all directions.  

The instrument was carefully calibrated in the wind tunnel in the Mars simulation laboratory and it was therefore possible, using lots of pictures from the little Telltale, to get the best wind measurements ever recorded on Mars during the 150 days the mission lasted. 

Mars Science Laboratory, 2012

In November 2011, NASA launched a new mission to Mars, the 'Mars Science Laboratory' or MSL, which carried the rover Curiosity. After a nine-month journey, it landed on Mars in the scientifically exciting Gale Crater.

One of the interesting results from this mission was the discovery of traces of ancient streams that proved that there was once liquid, flowing water on Mars. This could be concluded from a study of the unique erosion of rock in water.

When rocks are eroded by the wind, they are angular and rough – just like sandblasting. When rocks are eroded by water, they look completely different. They tumble around and bump into each other and gradually the corners and edges wear off and the rocks become smooth and rounded. Thus, researchers could clearly conclude from the shape of the rocks, that the erosion must have been caused by relatively strong flowing streams that could be compared to a typical Danish stream


The Mars rover Curiosity landed 6 August 2012 in the large Gale Crater, located in the border area between the northern and southern hemispheres. The crater is 154 kilometers in diameter and the rim of the crater is almost five kilometers high. In the middle of the crater is the mountain Mount Sharp, which is also approximately five kilometers high. The area is particularly interesting, because in the lowermost layer of the mountain you can find sediments with water containing minerals from the planet’s history more than two or three billion years ago, when the climate was completely different than today. (NASA/JPL-Caltech)

Mars has thus been a habitable planet with flowing water – the studies in the lowest lying area reached by the Mars rover Curiosity showed, for example, that this area is an ancient lakebed containing both clay minerals and sulphates.

The next mission - Mars 2020

The minerals that were found in Gale Crater showed that the area was not formed in an acidic or alkaline environment, but at a neutral pH. Since the area is also characterised by an elemental composition that – apart from organic material – is like good agricultural land, these results combine to demonstrate that this particular area in the Gale Crater on Mars was once habitable at least for microorganisms.   

But has there ever been life? – and when a manned mission is sent to Mars, how will the astronauts get oxygen to breath when they are out there? That is what the next mission, Mars-2020, will try to find out and the mission has Danish participation with the Mars Group at the Niels Bohr Institute, who are involved with two experiments, Mastcam-Z and MOXIE.

Mastcam-Z is a stereo camera that sits on the mast, which both can see far out into the terrain and can zoom in and capture close-ups. MOXIE stands for 'Mars OXygen In situ resource utilization Experiment', and it is an instrument designed to produce oxygen from the CO2 that is already found in the atmosphere.

An artist’s bid for the upcoming rover for the Mars 2020 mission. (NASA/JPL-Caltech)

There is virtually no oxygen in the Martian atmosphere, so the ability to produce oxygen is preparation for manned missions to Mars, when people will need to be able to breathe and get the necessary oxygen.

In addition, oxygen will be needed for a return rocket, in which the visitors will travel back to Earth again.

The Mars 2020 rover will also take core samples of the subsurface and here the goal is to find deposits that might contain fossils or other signals of, for example, microbes in stone. The idea being that the samples will be stored on Mars so that they can be brought to Earth by a later mission.

The Mars 2020 rover will be launched in July or August of 2020 and the trip to Mars will take seven to nine months. According to the plan, the rover will conduct experiments for a Martian year (nearly two Earth years).

The Mars Group will thus help in the planning of the scientific experiments that will carried out on the red planet – including the choice of the samples that will eventually be brought back from Mars.

Thanks to:

  • Anne Knudsen, Jens Martin's widow, for pictures and memories
  • Morten Bo Madsen, associate professor of physics at the Niels Bohr Institute, for stories and help arranging the scientific portion of the portrait in particular 

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