Infinite Martian mudslides in a Dutch airplane

When we send a rover to Mars, a Martian mudslide or landslide could bring a sudden end to years of hard work and investments. Scientists are therefore eager for more detailed knowledge about the nature of these landslides. But Martian gravity is much lower than Earth’s, and we don’t know how that affects mudslides on Mars. In a world-premiere experiment together with Delft University of Technology, earth scientist Dr Lonneke Roelofs is investigating how a Martian mudslide would behave under lower-gravity conditions.

Lonneke Roelofs studies natural disasters, such as earthquakes, mudslides and avalanches on other planets at Utrecht University’s Faculty of Geosciences. She had already studied how Martian mudslides move under lower air pressure using a special tank in the laboratory. But now she’s aiming higher - literally - to include the factor of Mars’ lower gravity in her experiments. During a parabolic flight aboard an airplane, she can compensate for part of Earth’s higher gravity.

Earthly perspective

Her goal is not only to learn more about mudslides on Mars, but also how they work on our own planet. “We look at these phenomena from an ‘Earthly’ perspective, which is only logical. But that means we might be overlooking something”, Roelofs explains. “So by changing what would normally be a constant factor, like gravity in this case, you can conduct truly fundamental research into the dynamics of mudslides. And when you approach a problem from a completely different angle, you occasionally notice something unexpected.”

Parabolic flight

To facilitate Roelof’s experiment, the pilot will conduct what is known as a parabolic flight, during which the gravity on board can be reduced. These flights are often used to train astronauts under weightless conditions or to study the influence of gravity on biological processes. But they are almost never used to conduct earth science experiments. This is just one example of the innovative shift in the planetary sciences in the Netherlands. “As an earth scientist, you can also study other planets”, Roelofs emphasises. “Planetary research is still fairly small-scale in the Netherlands, but I strongly believe that it’s world-class.”

Washing machine

To simulate mudslides and landslides aboard the aircraft, Roelofs has built a test installation that somewhat resembles a washing machine. “We use it to turn the experiment on its head: in the rotating drum, we can simulate an infinitely long slope, but one where the base is constantly being pulled out from under the rubble (like a carpet being pulled out from under one’s feet), instead of the rubble flowing over the base. Both have the same result, of course. Then we measure how the mudslide or landslide acts under lower gravity conditions during the parabolic flight.”

Sensors

There are three ways to conduct these measurements. The first uses sensors built into the rotating drum, which measure the thickness of the mudslide flow. Other sensors are installed outside the drum to record the mudslide’s weight and the direction and scale of the simulated gravity. These measurements are necessary because the pitch of the aircraft changes through a parabola and the aircraft’s own sensors are located at a different location than the experiment. The researchers correct for the difference after the experiment. Finally, the experiment is also recorded on video.

Flying laboratory

The experiment will be conducted in the PH-LAB: a twin-engine Cessna Citation II jet used by Delft University of Technology for research and education. The lab is affiliated with the Expertise Network Planetary Science, which enables Dutch planetary scientists to conduct observations in this unique flying laboratory. Alongside research test pilot Hans Mulder, the aircraft carries a crew of four scientists: Lonneke Roelofs herself, her colleague Dr Tjalling de Haas, planetary scientist Dr Sebastiaan de Vet from Delft University of Technology, and a technician from Roelofs’ lab. The flight will last around one hour, from Rotterdam Airport to the test area where the researchers can conduct their experiments safely, and then back to the starting point. The experiments are scheduled for Wednesday, 18 June and Thursday, 19 June. After the first flight, the test installation will be recalibrated and adjusted as necessary. If one of the flights is cancelled, for example due to inclement weather, then the experiments can continue on Friday, 20 June.

Grant

The study of lower-gravity mudslides is a collaborative effort by Utrecht University and Delft University of Technology, as part of the Expertise Network Planetary Science. The network’s mission is to facilitate collaboration between researchers from different fields of planetary research and the industry, to prepare for new satellite missions, and to create visibility to the research community as a whole. To achieve that mission, the network has received funding from the Netherlands Space Office. For more information, please visit: www.planeetonderzoek.nl