
Alexander Moore, doktorand, analyserade ytmaterial från asteroider.
Airborne experiment in zero gravity
Alex Moore, PhD student in Atmospheric science at Luleå University of Technology, successfully conducted an experiment in the sky to validate penetrometry, commonly used for cheese maturation, as a method to analyse the granular surface of asteroids.
“Very little is known about the underlying physics of penetrometry, hopefully the result of this experiment will contribute to the usage of penetrometry for future sample-return missions in space,” Alex Moore says.
Penetrometry is, simply put, the science of sticking a metal rod into a surface to understand the properties of that surface. Alex Moore used a robotic arm and several linear actuator motors which pushed the metal rods into the samples during microgravity to understand how and if the method would be valid in space.
“There have been past sample-return missions, like OSIRIS-REX and Hayabusa-2, where samples have been brought back to discover what these bodies are made of. However, there has been conflicting evidence and reports about the properties of the granular surface material, that is why this experiment has been critical to secure future sample-return mission,” Alex Moore says.
The usage of penetrometry has been mostly limited to ground-based studies, such as soil science and cheese maturation. Thus, very little is known about the underlying physics of penetrometry which makes it a challenge if we want to apply it in space. And because one cannot eliminate gravity in a laboratory it has to be conducted during a parabolic flight.
“Understanding the mechanical properties of solar system bodies, such as asteroids, is essential for understanding both their origin and evolution,” Alex Moore explains.
Microgravity on Earth
As the goal of this experiment was to gather data on how penetrometry would perform in space as well as to see whether it would be feasible to use the robotic arm in such an extreme environment it would need to be conducted in microgravity. However, it is rather expensive to travel to space so instead the experiment was conducted in Bordeaux. In fact, it took place in a special retrofitted plane above the French city during what is called a parabolic flight.
The parabolic flight creates a microgravity environment by flying in 45-degree angles, where at the top of the curve a microgravity is created for around 20 seconds. During one of these flight 30 parabolas are conducted. This is a great way to simulate a microgravity environment without having to go into space.
“It was an incredible experience. Some would liken it to going over the top of a rollercoaster, but I would say it is very different. During each parabola you experience a gravity of 2g as the plane climbs, the downwards pressure is very intense as you weigh twice as much. Then you hit the 0g gravity phase and you go from double your weight to weightlessness, which is a very fun experience,” Alex Moore says.
The results
One of the goals were to test the feasibility of the robotic arm in extreme environment such as in microgravity. During the experiment the arm worked without a hitch, so the proof of the feasibility was a huge success.
“This opens for a great wealth of possibilities and applications for this robotic arm in a microgravity experiment and the potentiality for further campaigns testing its uses,” Alex Moore says.
All the data has not yet been analysed, but from the live data Moore saw during the flight he expects a good degree of success for the penetrometry section of the experiment. The next step will be to do the tests in an environment of 1g gravity to be able to compare the results. However, he is confident that the data collected will make for some interesting findings.
Contact
Alexander Moore
- Research Assistant
- 0980-67548
- alexander.smyth-moore@ltu.se
- Alexander Moore
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