Recent experiments on levitating fruit flies using diamagnetism could serve as a proxy model for the effects of microgravity in space.
Researchers at Nottingham University found that the levitating flies walked faster than normal — the same effect observed in earlier experiments on board the International Space Station and Shuttle.
‘In the original experiments it wasn’t clear whether it was microgravity that was causing these effects because they had to compare the behaviour of flies in space with a control group of flies on the ground,’ Dr Richard Hill of Nottingham told The Engineer.
‘Despite all their efforts to ensure each group of flies had gone through the same environmental conditions, the flies on the ground had not gone through all the launch procedures which involved cold storage, transport to the launch site, then high g-forces endured on board. We can be quite confident now that the changes in behaviour were down to microgravity… and that we can simulate that on the ground.’
Their experiments rely on a phenomenon called diamagnetism. Unlike ferromagnetic materials such as iron, which are strongly attracted to magnetic fields, most biological materials are weakly repelled from magnetic fields.
So the researchers have to use a powerful superconducting magnet to produce a very strong magnetic field of around 16 Tesla — approximately 350,000 times stronger than the strength of the Earth’s field.
‘What we’re doing is counteracting the force of gravity using the diamagnetic force, which is acting on each molecule of the organism,’ said Hill. ’So in that sense we can make this comparison between the centrifugal force that is acting on astronauts in orbit, which balances out the force of gravity.’
Fruit flies were chosen for the experiments because they serve as a model organism in biology whose genetic, biochemical and neural pathways are very well understood.
Indeed in the next set of experiments, due to be published soon, the researchers examined the flies’ transcriptome — the sum of all the different genes actively expressed — after variable periods in a levitating state.
‘One possibility for this technique [diamagnetism] is to use it as a screening tool for experiments that might go into orbit; without taking the expense to launch rockets into space we can see which experiments are going to be suitable and interesting,’ said Hill.