Danes on Mars

Posted by Emily Lakdawalla

2008/07/17 08:41 CDT

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I was delighted to receive an email nearly two months ago (yes, I'm that behind in responding to email) from Morten Bo Madsen, who I knew from the Mars Exploration Rover mission as "that Danish magnet guy," the fellow responsible for the magnet experiments on nearly every American Mars mission. The magnets were originally designed to study the properties of airborne Martian dust, which would help determine its composition. The team was rather surprised to learn that nearly all Martian dust responded to the fields surrounding their magnets. One type of magnet carried by the rovers -- called the sweep magnet -- was ring-shaped, and the shape of its magnetic field caused the dust to fall on the ring but not onto the hole at the center of the ring. So it developed that the center of the sweep magnet was just about the only thing left on the rovers that was clean after rover operations dragged on and on and on, and soon the imaging team was using the continued relatively pristine condition of the sweep magnet to help calibrate their images.

NASA / JPL / Cornell

Spirit's cleaning event: before and after

These two pictures show Spirit's calibration target (the "Marsdial") before and after a cleaning event wiped Spirit's deck and solar arrays clean of the dust that had accumulated during the first 400-plus Mars days of its operations within Gusev crater. The pictures were taken ten days apart, on March 5 (left) and March 15 (right). On the "before" image, the only spot that is not completely covered in reddish Martian dust is the center of the sweep magnet, located immediately to the right of the Marsdial.

So the team was invited to participate in the Phoenix mission not just to continue their scientific study of the magnetic properties of Martian dust (which they do with a set of magnetic substrates provided for the MECA microscopy station), but also to help design a calibration target for the cameras that could likewise remain clean throughout the mission.

NASA / JPL / UA / Texas A & M / color composite by Emily Lakdawalla

Calibration target on Phoenix

Phoenix is equipped with several calibration targets to help the camera team make sure camera images taken many sols apart can be directly compared. Underneath the six large gray and color chips on the periphery of the calibration target are ring-shaped magnets that attract Martian dust to the outside of the target while keeping the center of the target clean.

Consequently, yet again, those Danes are back in Mars landed mission operations! Morten sent me this photo:

Danish contributors to Phoenix

From left: Morten Bo Madsen, Lone Djernis Olsen, Kristoffer Leer, Christina von Holstein-Rathlou, Mads Dam Ellehøj, Line Drube, and the Icelandic "Dane" Haraldur Páll Gunnlaugsson (the Danes call him Palle).

Morten says: "Palle, at the far right, is instrument-provider (the Telltale) and Phoenix Co-investigator from Institute for Physics and Astronomy, University of Aarhus. Morten (far left) is instrument-provider (radiometric color calibration targets and magnet-substrates for the microscopy station of the mission and Phoenix Co-investigator from the Niels Bohr Institute, University of Copenhagen). All the young persons between the two of us are physicists, most of them Ph.D. students, in our group. Lone works with the MECA team on data from the MECA microscopes, Kristoffer is working for the Robotic Arm Camera team and will participate in the interpretation of magnetic properties of airborne dust on the iSweep/Caltarget and MECA substrates, Christina will work with Palle on interpretation of telltale images, Mads with the TEGA and Line will work with Kristoffer and me with atmospheric dust and mineralogy using the iSweeps. Many of us have additional operational tasks - for instance, Line has been in charge of preparing the End-of-Sol reports for the Atmospheric Science Theme Group."

Image c

Not pictured here but also very involved in the magnetic properties experiments are Robert B. Hargraves, who was responsible for the magnetic properties investigation on the Viking missions, and Jens Martin Knudsen, who helped Morten and Rob Hargraves develop the magnets on Pathfinder, the rovers, and Phoenix. Morten said, "Improving the investigation by including more magnets than on Viking was originally Jens Martin's idea -- I just took upon me the responsibility to develop the idea into something practical. But Rob and Jens Martin were the ones to initiate magnetic properties investigations on Mars -- and Jens Martin was the one who put Denmark on the map regarding research using Mars landers.