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Backgrounder

A Canadian Experiment Onboard Space Shuttle Endeavour (STS-118)
Perceptual-Motor Deficits in Space (PMDIS)

Space shuttle pilots and payload operators need quick and accurate hand-eye coordination to manoeuvre objects in space. To dock the shuttle safely to the International Space Station, for example, the pilot must be accurate within a few centimetres while both vehicles move through space at 30,000 km per hour.

Manoeuvring a satellite worth tens or hundreds of millions of dollars with the shuttle's Canadarm, or handling a truss weighing close to 20 tons with the Space Station's Canadarm2, are also delicate operations requiring very precise hand-eye coordination.

Yet, experience and science experiments have shown that, while in microgravity, astronauts have a harder time reaching and pointing to objects than when they are on Earth. This could be critical in emergency situations.

Dr. Barry Fowler, a neuroscientist at York University, is researching the causes of this reduction in hand-eye coordination. To study Perceptual-Motor Deficits in Space (PMDIS), Dr. Fowler designed an experiment that resembles a simple computer game.

During Mission STS-118, Canadian astronaut Dave Williams will be put in front of different situations: in some trials, he will use a joystick to click on the targets, while in others, he will tap directly with a pointer on the touch screen specially designed for this experiment. The difficulty of the task will vary with the size of the targets. In other trials that simulate multi-tasking, he will be asked to push a button in response to a tone while hitting targets.

Astronaut Williams will perform these tasks under two conditions: while floating in the microgravity of space or anchored to the station by a seatbelt. A wristband will keep the astronaut's arm in a stable position. The computer will record the speed and accuracy of the target taps.

The results of the PMDIS experiment will help Dr. Fowler and his team determine if the loss in hand-eye coordination is due to one or a combination of the following:

• the brain not adapting fully to the weightlessness of space;
• the difficulty of performing mechanical tasks like pressing a button while floating in space; or
• distractions caused by flashing lights, floating objects, co-workers and some very spectacular scenery.

Once the 'why' of perceptual-motor deficits in space are known, researchers like Dr. Fowler can start looking at how to remedy this problem. Countermeasures could include instruments that take into account limited coordination capacities during weightlessness. This research in space could also lead to insights in the medical field on how the brain adapts or doesn't adapt to disease or injury that can confound hand-eye coordination.

Bristol Aerospace Limited from Winnipeg, Manitoba, was commissioned by the Canadian Space Agency to build the PMDIS hardware. Dr. Fowler's research is also supported financially by the CSA.

PMDIS will return to Earth after STS-118.

June 2007