News - November 21, 2017

Study into influence of Mars radiation on plants

Roelof Kleis

Mars endures roughly 20 times the radiation we do on Earth. Can plants handle this? Nynke Tack, bachelor’s student of Plant Sciences, investigates this.

© Roelof Kleis

Not by going to Mars and back – that remains beyond our current capabilities. But her research is meant to contribute to the answer on the question whether we will ever be able to live on Mars. In the meantime, Tack remains closer to home, at the Reactor Institute Delft, which is part of Delft University of Technology. There, she will irradiate plants as if they were growing on the surface of Mars.

Tack’s experiment is part of Wieger Wamelink’s research. He has been trying to figure out whether – and if so, how – vegetables can be grown on Mars.  Wamelink assumes that horticulture on Mars will have to be done underground, as the radiation levels on the surface are far too high. But that is an assumption. ‘I might be wrong, which would only be great news, as that would mean we won’t have to cultivate the vegetables underground.’

We can only simulate the equivalent radiation dose, not the actual radiation spectrum on Mars.
Nynke Tack

Plants on Mars would endure a daily dose of about 610 microsievert. For comparison: that dose is only 36 microsievert on Earth, which is quite a difference. But according to Tack, that seemingly high dose should still be manageable. ‘The doses we use to induce mutations are of the order of magnitude of several sievert, so tens of thousands of times higher.’ What is expected to be much more harmful than the standard dose on Mars are the peaks in radiation levels caused by explosions on the surface of the sun.

Solar flares
To study this as well, Tack will not only simulate the ‘normal’ radiation, but also the radiation caused by solar flares. This will be achieved by administering 50 times the daily dose. Note that this too is just a simulation. Tack: ‘We can only simulate the equivalent radiation dose, not the actual radiation spectrum on Mars. That would also require high-energy protons and neutrons.’ Tack uses gamma-rays from Cobalt-60 isotope sources.

06-NIE foto Wieger Wamelink Sven Menschel-1.jpg

To be allowed to carry out the radiation experiment, Tack must go through an extensive training. The final examination of this training is half-way the planned experiments. ‘To be able to start with the experiment, I will be appointed a babysitter to guide me during the first few weeks’, she chuckles. Tack will start later this month and should be done by the end of the year. The will conduct the experiments with cress and rye. She left for Delft last Sunday with everything she will need, as she will be living there for the duration of the experiment.

This week, Wamelink concluded his worm experiment. He grew wild rocket (the salad!) on Martian soil, both in the presence and absence of worms. A highly remarkable side-effect came up during this experiment: some of the worms procreated. ‘In one of the pots, we encountered not only the four worms we had placed, but also a youngling. The first alien life’, Wamelink says jokingly. Wamelink found two other younglings in other pots as well.