Inner-ear testing in outer space

A group of Atlantic Ocean toadfish are enjoying the trip of a lifetime, 170 miles overhead on board the space shuttle Columbia…

A group of Atlantic Ocean toadfish are enjoying the trip of a lifetime, 170 miles overhead on board the space shuttle Columbia. They make up one of the most unusual collection of space travellers launched into orbit.

They are participants in Neurolab, a long-duration shuttle flight aimed at better understanding the effects of weightlessness on the nervous system and on systems that control balance. The 26 separate experiments are packed into the European Space Agency-built reusable Spacelab, on its last flight after 15 years being carried aloft aboard the shuttle.

The mission could just as well be called the Noah's Ark flight. There are cages of rats, tanks of toadfish and swordtail fish and 1,500 crickets on board, and the flight's human car go, a seven-member team including four doctors, will also participate in a variety of experiments.

One of the least appealing is a purpose-built ESA developed mechanical chair which can spin the astronauts at a stomach-churning 45 revolutions a minute. The object of this human centrifuge is to study the role of the inner ear in detecting changes in motion and spatial orientation.

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The astronauts were unlikely to suffer from motion sickness during the spins, according to Dr Bernard Cohen, an investigator with the Mount Sinai School of Medicine in New York. They will already have come through a bout of space sickness, a short-term malaise which affects most space travellers as they first encounter weightlessness.

The effect is caused when the pull of gravity disappears in orbit, and the balance and motion systems, the semi-circular canals and otolith organ in the inner ear, go into sensory overload.

Susceptible Earth-bound travellers experience a version of space sickness in ordinary motion sickness.

"You can't think, you can't move, you can't eat, you can't do anything but lie still," said Dr Stephen Highstein, professor of otolaryngology and anatomy at Washington University School of Medicine in St Louis.

Dr Highstein is the chief scientist for experiments involving the toadfish, among the stars of the Neuro lab show. "The inner ear of these fish, which helps sense motion, is highly similar to that of humans and other mammals," he said.

The fish have been surgically attached to sensors which will measure the impulses passing from their balance system to their brain. Re searchers will be able to record changes in the impulses as the fish adjust to microgravity, information which could help in developing methods to counteract space sickness, he said.

Many of the experiments involve studying how sensory organs, brain tissue and nervous systems of rats, snails and crickets develop in a microgravity environment. The 135 snails will be housed in a "closed equilibrated biological aquatic system", the phrase used by the National Aeronautics and Space Administration for what earthlings would call a fish tank.

It isn't all hard work for the astronauts. Another experiment involves throwing a ball back and forth. The object is to evaluate whether the crew can predict the trajectory and catch a ball thrown in microgravity. Yet another experiment involves monitoring how astronaut sleep patterns are affected during space flight.

There is real science imbedded in all the Neurolab experiments, however. Insomniacs, long-haul air travellers, those susceptible to motion sickness and vertigo and people who get dizzy when they stand up too quickly could all benefit from what is learned during this flight.