What do you hope to find out from that?

This is all part of NASA's artificial gravity programme, which is important because many of the problems with human space flight are associated with weightlessness and the effect on the brain, the muscles, the heart and so on, and the fact that the longer you are in the weightless environment the worse things get. Because Mars missions entail a journey of six months out and six months back, plus a stay on the surface for as much as a year and a half, you are talking about a thousand days where all of it is spent either in reduced-gravity or microgravity environments.

So what can we do to counter that?

Give the astronauts drugs, get them to do exercise. But none of these is uniformly effective as far as I can tell. The new thinking is we take our light, our heat, our fuel, our atmosphere - so why don't we take gravity as well? And then the question is how do you take gravity with you? There is the thought that you could use short-arm centrifuges, small enough to stay inside a relatively small vehicle at a radius of round about 3 metres, and spin people at around 40 revolutions per minute. Also you could give them a short but intense burst of gravity a couple of times - use gravity almost as a drug. If you can accept that concept, then you need to know if it would work and what the dose should be. And that's where the research programmes in Johnson Space Center are starting from. Later on this year if I'm really unlucky, I'll get to go on one of those centrifuges.