”I landed lying down on my back and reached for my camera — it felt amazingly heavy, like a huge 50lb lead dumbbell. It was incredible. Just putting one foot in front of the other required tremendous effort.” So reported astronaut Andrew Thomas when he returned to Earth after five months on board the Mir space station in 1998, staggering forward, lurching to one side, overcome by vertigo and wasted muscles.
To preserve the dignity of their returning astronauts, Nasa scoops them out from shuttle spacecraft with mechanical movers, curtained off so no one can see the wrecked astronauts barely able to stand. In fact, many are ferried away in wheelchairs. Forget about the Dan Dare adventures, space travel seriously damages your health. Astronauts can be wrecked by long spells in space: muscles shrivelled, bones weakened, heart strained, lungs struggling.
It all sounds strangely similar to old age. In fact, overcoming the problems of space travel may well point to cures for osteoporosis and many of the other ills of ageing on Earth. For Nasa, the medical questions are reaching crisis point as they plan to send a group of astronauts on a three-year mission to Mars, taking 12 months to fly each way. It is planned for the year 2020, and although you might think there would be masses of technical problems to overcome, Nasa seems reasonably confident of building the rockets and the space capsule. No, the biggest headache is the astronauts themselves.
Humans were never designed for zero-G. We evolved to thrive, where muscles and skeleton, working against the Earth’s gravity, makes them grow strong. Even with rigorous exercise, cosmonauts on the Mir space station lost 1-2% of their bone mass each month. The risk of breaking a bone during a three-year mission to Mars has been calculated at around 30%, with horrific consequences.
”A limb fracture involving one of a six-person space crew could seriously compromise a mission’s objectives,” explains Jay Shapiro, at the National Space Biomedical Research Institute. For a human body, being weightless is like being confined to bed in a total body cast. Apart from bones, the muscles also waste away from lack of use, and some, like those in the calves, can lose around 20% of their mass in zero-G. Tendons and ligaments can weaken to the point that they tear like tissue paper. The lungs and other major organs suffer.
Blood feels the lack of gravity, too. When we’re standing on Earth, blood sinks to the feet and leaves the brain lighter, creating a gradient of blood pressure through the body. But in space, the pressure gradient disappears and the body thinks it’s in trouble and makes less blood, which spells trouble for the heart.
”If you have less blood, then your heart doesn’t need to pump as hard; it’s going to atrophy,” explains Victor Schneider, research medical officer at Nasa. ”It’s a classic case of ‘use it or lose it’.”
Medical researchers are trying to find magic drugs to fight bone loss, perhaps using the natural hormones or enzyme factors involved in building healthy bones. Nasa is also trying to develop gadgets to keep astronauts fit, but exercise alone is not enough. Alan Hargens, an orthopaedic specialist who recently worked at Nasa, states: ”You can’t just put high loads on the bone and then expect it to recover if you’re not taking care of the blood flow to that bone as well.”
One device he is working on looks like a spin-tub dryer, worn around the bottom half of the body, featuring a treadmill inside kept at low pressure with a vacuum cleaner. ”We’ve found that we can provide body weight by applying negative pressure over the lower body,” says Hargens. The machine restores the blood pressure gradient, strengthens the heart and muscles and also cuts down on bone loss.
If it lives up to its billing, it may be used on Earth to help rehabilitation in injuries, stroke, surgery or prolonged bed rest. Returning from space to Earth is equally traumatic once the body has got used to weightlessness, as astronaut Andrew Thomas described after his Mir venture. Bone recovery is the biggest problem and, after a six month space flight, it can take up to three years to repair the damage, if the bones fully recover at all.
Going where no man has gone before sounds like great fun, but it is pushing the human body way beyond what it was designed for. Once we conquer these problems, however, perhaps we will colonise space — and improve life for millions of the elderly on Earth. – Guardian Unlimited (c) Guardian Newspapers Limited 2001