The European Space Agency (ESA) has expressed interest in an instrument from Risø DTU that may prove useful in explorations of the red planet.
By Marianne Vang Ryde
A barren, stony desert covered in red dust – that is Mars today. But there are indications that there has been plenty of water and a much warmer climate in the past, begging the question – was there also life? At the Radiation Research Division at Risø DTU, a small team of researchers is developing an instrument that could help describe the climate change that took place on our neighbouring planet and bring us closer to an answer. Every year, Risø DTU sells approx. 25 examples of one of the best instruments in the world for dating sediments. It is the so-called OSL reader (Optical Stimulated Luminescence) and 275 instruments have been sold so far, with the reader undergoing continuous refinement and development to fulfil specific objectives.
The European Space Agency (ESA) learned of this unique competency four years ago, and researchers at the Radiation Research Division were commissioned to find out whether OSL technology could also be used on the planet Mars, which consists of entirely different materials than Earth. The answer was positive, and ESA was so satisfied with the reports on this pilot project that a brand new project has now been launched. The assignment this time is to determine more precisely the physical design of the instrument in order for it to be part of a Mars mission.
From 80 kilograms to 600 grams
Bent Lauritzen, head of programme, Mayank Jain, head of project, and Torben Lapp, development engineer, bring out a small model made from porous plaster saturated with glue. The model has been drawn on a computer and then printed out using a 3-D printer. „Of course, this is not the right material. This model can only be used to assess the mechanics,“ explains Mayank, who goes on to describe in detail how a sample from the sediment on Mars can be placed into one of three holes in the ‘stomach’ of the instrument, after which a dial can be turned to allow a new sample to be placed in the next hole.
The movement is, of course, remote-controlled electronically from the control centre on Earth. „Our OSL reader weighs nearly 80 kg and is as large as a milk crate, but in order to qualify for the Mars mission, it needs to be smallerthan a milk carton and weigh no more than 600 g,“ says Bent Lauritzen. „That’s why the Mars instrument can only hold three samples at a time.“
Inside the OSL reader, a sample of a mineral is exposed to various light spectra. And by measuring the light signal reflected from the mineral, it is possible to say how much time has passed since the mineral was exposed to sunlight. The signals are an expression of the radiant energy stored in the material. „They must be exposed to laser light at different wave lengths, which is usually done by changing filters. But because we can’t send a technician to Mars, we have to include three different light units – one blue, one red and one green. There also has to be room for a sensitive detector and a radiation unit capable of calibrating the sample by giving it a test dose from an x-ray or beta source,“ Mayank Jain continues.
Design and technological solutions are at the heart of this project, which will be concluded in 2010 and which also involves the Dutch company cosine Research. Besides the actual model, an end product that is just as important will be a technological road map providing a detailed recipe for how to move on to the next step – an actual space model.
„The instrument won’t be launched for at least five years. It won’t be ready for the next Mars mission, EXOMARS, and it’s not at all certain that ESA will even decide to bring our instrument along or even commission us to build it,“ says Bent. But the three researchers still feel there is a good chance that they will at least be taken on as consultants on a final project and perhaps even get the assignment of processing any data brought back by a dating instrument.
In any case, the project would give them important experience that they can use to transform the famous OSL reader into a portable model that will be even more useful than the milk-crate-sized lab model. „Of course, the collaboration with ESA will open many doors for us, and the agreement also entails that we will be able to sell our concept to NASA should ESA not require it after all,“ concludes Bent Lauritzen.
|From Risø DTU to Mars
The OSL reader (Optical Stimulated Luminescence) is being developed in collaboration with the Dutch company cosine Research, which is responsible for developing the electronics. DTU Space has carried out a so-called planetary protection study in an effort to ensure that the instrument does not bring live material (bacteria or viruses) from Earth to Mars.