Living in space is bad for you.
Any astronaut returning to Earth from the International Space Station (ISS) does their best to smile for the cameras but struggles to stand. So, imagine what it will be like for future missions to Mars. After several months cooped up in zero (or micro) gravity, the first astronauts to step onto the Martian surface will barely be able to manage an ungainly stagger, let alone a giant leap.
“There’s a variety of different effects that can happen,” says Nasa biologist Sharmila Bhattacharya. “There’s a reduction in bone density, there’s loss of muscle and vision can be affected.” Her recent studies suggest that spaceflight even compromises the immune system.
Add in difficulties with balance, sleep deprivation, a slowing of the cardiovascular system, not to mention excess flatulence; throw in a bit of space sickness, vertigo and lethargy, and you begin to understand the scale of the problem. Bhattacharya’s experiments, along with countless others carried out over more than fifty years, attribute most of these symptoms to the effects of living without gravity.
It seems humans have not evolved for life in space.
As a result, there are several ongoing initiatives to try to understand - and minimise - the impact of weightlessness. The European Space Agency, for instance, recently ran a series of bed rest studies, examining the effects on volunteers of 21 days of inactivity. And a forthcoming year-long joint Nasa/Russian mission to the International Space Station (ISS), is designed to put the latest theories on combating weightlessness, such as improved exercise and nutritional regimes, to the test.
However, if mankind is to travel to Mars, the moons of Jupiter, Saturn or beyond, we may need more extreme solutions. And one of those includes resurrecting plans all but abandoned by Nasa in the 1970s: spacecraft with their own artificial gravity.
Early designs for space stations all assumed that artificial gravity – generated by enormous spinning wheels - would be the norm in the future. Take an example from the 1949 issue of the Journal of the British Interplanetary Society written by H E Ross, which envisages a “refuelling station” on the way to the Moon. The design consists of three sections, rather quaintly labelled, “a bowl, bun and arm.”
The bowl is effectively a giant mirror, designed to concentrate sunlight that heats water to produce steam for power generation. That’s right, a steam powered space station. The bun – which looks more like a bagel – is located behind the mirror. The arm pokes out on the side of the bun and is linked to a docking port.
With any rotating wheel in space, the artificial gravity, or as Ross more accurately puts it “the pseudo gravitational effect”, works like this: thrusters rotate the bun/bagel around its axis, generating a centripetal force. Anyone inside this hollow wheel experiences a similar effect to gravity, as if they were being pulled towards the outer curved hull (although actually it is the floor of the hull pushing up against them). The amount of artificial gravity generated depends on the size of the wheel and the speed of rotation. The bigger the wheel and the faster it turns, the greater the effect. The result is brilliantly illustrated in the film 2001, where the astronaut jogs around the inside of the spaceship.
Towards the end of the Apollo Moon programme, in the late 1960s, Nasa commissioned studies from industry on future space stations. All the designs specified that artificial gravity would be essential.