A visit of the ice lab
What do the images of Mars, Comet Chury or other celestial bodies really show? For a reliable answer researchers at the University Bern study the optical properties of dust-ice mixtures that are analogs of planetary or cometary surfaces. Have a look at their laboratory.
Ices are ubiquitous in our solar system and beyond. “Their presence at the surface or subsurface of planets and comets causes dynamic processes such as ejection, flowing, or peculiar shaping of icy surface materials”, explains Antoine Pommerol, member of the Planetary Imaging Group at the University of Bern: “Our goal is to study these processes.” In order to simulate space conditions the researchers rely on surprising tools. “In an ice lab you always find hairdryers that are used to clean fogged glass,” says Antoine Pommerol: “In our lab we even work with a dryer for dog’s fur that is especially suitable for our purposes.”
In the centre of the black cylinder is a chamber, 30 cm in diameter and 32 cm high. There the researchers place the samples, for instance volcanic soil from Hawaii that resembles Martian soil or a dusty-ice sample as cometary analog. With liquid nitrogen and vacuum pumps, they create conditions comparable to the situation on Mars or in space with very low temperature and pressure. A xenon lamp simulates the light of the sun. Above the cylinder a camera is installed and on an arm at the side a microscope can be fixed. With these instruments the scientists study the temporal evolution of the samples.
The white machine with its long plastic tube was originally built for treating horses with asthma. It is an inhalator that nebulizes water and medicines to ease the health problems of the animals. “The device works with ultrasound and produces very fine water droplets that are the ideal basis for our ice,” says Antoine Pommerol: “We want to produce ice samples in a reproducible way.” Working with ice is difficult because it evolves very fast. But the researchers in Bern are so skilful that they even provide other labs with their samples.
The cupboard in the middle is a freezer with a very special interior. If you open the door it is pitch black inside and it takes a while until you see different elements among them a little table with the sample holder, a lamp and long arms with a transmitter and a receiver. The experiment is designed to measure the reflected light from a surface depending on the angles of incidence. The way a surface scatters light reveals properties about it, for instance how rough it is or how big the particles are.
“The microscope allows a quantitative interpretation of how the thousands of particles in a sample evolve,” explains Antoine Pommerol. Microscopic mages of water frost over a Martian analog for example show how the frost and the substrate interact. Simulating frost processes on Mars will help identify such features on images that will be taken by CaSSIS, the Colour and Stereo Imaging System that was built in Bern and now is in Mars orbit on-board ESA’s TGO. More information about the ice lab: http://pig.space.unibe.ch/science/lossy.html