Partial gravity? On Earth?
Most of us, including the author, assumed extended duration microgravity or partial gravity research is not possible on Earth.
We know of evacuated drop towers, the elegant zero-G parabolic flights on airplanes, but these typically last only seconds or, in the case of sounding rockets, a couple of minutes. This requires carefully designed experiments that have to work perfectly within the small time window, a challenge and headache for the designers.
But it turns out that more than a decade ago, in 2006, a technique was already developed to perform long duration experiments… on your desktop. How could I have missed that?
But there is a caveat. The device is tailored for the study of cell cultures or experiments with a limited volume. Still, in many cases this can lend valuable insight in the processes taking place in the actual space environment.
The Device is called a Random Positioning Machine (RPM). Unfortunately, the name does not refer to a desktop-quantum-field-confabulator-stargate-thingy, (or the infinite probability drive in Hitchhiker’s Guide to the Galaxy); it just means that an effect similar to what samples experience in microgravity is created by spinning samples in a randomized fashion. The device functions like the miniature version of the hamster-wheels early astronaut-pilots were trained in, as evidenced in the following clip:
The somewhat underwhelming action of the RPM (we prefer the sight of nauseated screaming volunteers or determined astronaut-pilots) does have important use cases.
Applications in Microbiology: Martian soil detox.
In a beautiful application of this technology, researchers are experimenting with the detoxification of the Martian soil.
Rich in perchlorates, which is both a plant fertilizer, rocket propellant and source of oxygen, contact with the Martian soil potentially taxes the human thyroid and longs, which requires a mitigation strategy be it preventative medication (iodine pills), decontamination or soil and dust treatment. The risk of other nasties like chromium, heavy metals in general, or the physical size of Martian dust and its potential to shorten the life span of equipment or air filters, also needs to be studied and taken care off.
Active in synthetic biology, he works with bacteria that are engineered to solve problems that cannot be tackled – or are not tackled well – by ‘wild’ bacteria. A team of his students entered the iGEM International Genetically Engineered Machine competition with a solution to the problem of growing non-toxic plants on Mars, but needed ‘Martian’ gravity to test their ideas.
“The soil on Mars has perchlorate chemical compounds in it, which can be toxic for humans,” explains Prof. Claessen. High doses of perchlorate can inhibit the thyroid gland’s uptake of iodine and interfere with foetal development.
“Our students started ‘building’ a bacterium that would degrade the perchlorate to chlorine and oxygen, but they needed to know whether that bacterium would behave the same way in the partial gravity of Mars as it would on Earth.”
As its name suggests, the RPM continually changes its orientation at random, so that items placed within it have no opportunity to adjust to a steady gravity direction. The original design could successfully simulate zero gravity while the newer RPM 2.0 can additionally simulate partial gravity, the stages between normal Earth gravity and the weightless environment.
Prof. Claessen is now building a Dutch consortium to investigate soil detoxification on a larger scale. This will have applications on Earth. For example, there is a lot of perchlorate in Chile’s Atacama Desert, where the soil is believed to resemble that on Mars. Atacama soil was previously used as fertiliser in the US, but later it was found that perchlorate had been washed from this fertiliser into groundwater used for drinking.
For more information and links to the parties involved, we refer to the ESA article.