Medical Experiments

Elsewhere in the Spacelab module, the crew - which included two medical doctors (Brady and Thirsk) and a veterinarian (Linnehan) - also concentrated on the second complement of LMS experiments: the life science investigations. These were further categorised under five disciplines: human physiology, musculoskeletal, metabolic, neuroscience and space biology and, according to Victor Schneider of NASA's Life and Microgravity Sciences Office on 5 July, ''the information-gathering has just been tremendous. As a scientist, I think the amount of data we have is exciting.''

Two hours after launch, Favier and Thirsk kicked-off the human physiology investigations by donning electrodes and sensors to monitor their eye, head and torso movements for Canadian scientist Douglas Watt's Torso Rotation Experiment. It had been known for decades that many astronauts experience motion sickness in space - particularly during their first few days aloft, as their bodies adapt to the strange new environment - and the aim of Watt's study was to identify, and ultimately avoid, movements that contribute to this feeling of illness.

Meanwhile, Linnehan and Brady joined their colleagues in the torso rotation studies and participated in initial tests to evaluate their muscle strength and control. It was already known that muscle fibres became smaller - or 'atrophied' - in microgravity, which resulted in a steady loss of muscular mass. Many of these observations tend to be short-lived, generally vanishing when astronauts return to Earth, but the potential impact of longer-duration, six-month stays on the International Space Station on human muscles and bones remained largely unknown.

Using an ESA-built device known as the Torque Velocity Dynamometer, akin to a piece of exercise equipment found in a gym, the crew were able to take precise measurements and calculate their muscle performance and function, including strength, amounts of force produced and resultant fatigue. Blood samples were taken throughout the mission to enable ground-based physicians to better understand metabolic and biochemical changes in their bodies while in space. Additionally, the Astronaut Lung Function Experiment was used to gauge microgravity's impact on lung performance and respiratory muscles during rest and periods of heavy exercise.

On 22 June, the human physiology studies entered the first of two specialised three-day 'blocks' of time to probe changes in sleep and performance patterns. It marked the first-ever comprehensive study of sleep, circadian rhythms and task performance in space and, according to Principal Investigator Timothy Monk of the University of Pittsburgh, was essential ''if we are going to do long-term exploration in space. We have to know what happens when we remove ourselves from real-time cues.'' As astronauts circle Earth every 90 minutes - experiencing 16 'sunrises' and 'sunsets' in each 24-hour period - their 'normal' timing cues alter significantly.

Investigators hoped that such studies might be beneficial to workers on Earth, whose normal work and sleep schedules change regularly, as well as sufferers of jetlag. Additionally, ''ageing and depression are related to the 'clock' going wrong,'' said Monk. Typically, during the sleep experiments, all four science crew members -

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Linnehan, Brady, Favier and Thirsk - wore electrode-laden skullcaps which monitored their brain waves, eye movements and muscular activity. A second block of time for the experiment began on 2 July when they filled in questionnaires at the start and end of their shifts and again wore the skullcaps while asleep.

Following Columbia's landing, the data from both blocks was compared to create a picture of how the astronauts' sleep patterns had changed during the mission. ''These were the first integrated studies where we could look at mood, circadian rhythms and sleep,'' said Victor Schneider. ''We need to know how we can help individuals in space and on Earth work different schedules.''

Extending this physiological research into the musculoskeletal arena were a battery of experiments to explore the underlying causes of muscular and bone loss, which featured the first-ever collection of muscle tissue biopsy samples before and after the mission. Almost immediately after Columbia touched down at KSC on 7 July, the science crew underwent MRI scans and biopsies for comparison with pre-flight samples. It was expected that this might lead to improved countermeasures to reduce in-flight muscular atophy. Pre- and post-flight data was also used in support of other investigations looking at changes in the astronauts' muscular activity in orbit.

The crew routinely used a bicycle ergometer in the Shuttle's middeck, which was fitted with a large, weighted flywheel surrounded by a braking band to resist imparting their pedalling motions to the hull, enabling the crew to exercise without disturbing the sensitive microgravity experiments. The Torque Velocity Dynamometer, already mentioned, was used to measure calf-muscle performance during these exercise periods; additionally, Linnehan and Favier wore electrodes on their legs which applied precise electrical stimuli to cause involuntary muscular contractions. Data from these experiments was expected to provide new insights into why muscles lost mass in space.

The dynamometer was also employed for musculoskeletal tests to measure the astronauts' arm and hand-grip strength. On 24 June, they strapped their arms into the machine, curling and extending them as it provided resistance. One of the investigators for the experiment, Pietro di Prampero of the University of Udine in Italy, commented a few days later that ''analyses so far have shown smaller changes in the maximal force of leg and arm muscles than expected.'' Overall, the dynamometer performed near-flawlessly, with the exception of a few mechanical setup problems and software glitches, and operated for 85 hours during the mission.

In light-hearted reference to all of the electrodes worn and blood and tissue samples taken from them, Linnehan, Brady, Favier and Thirsk jokingly called themselves ''the rat crew''. Even their food and drink intakes were carefully monitored, as part of ongoing studies of metabolic changes and calcium loss during spaceflight. They typically took non-radioactive calcium isotopes at each meal, from 10 days before Columbia's launch until a week into the mission, and by tracking its relationship to food-and-drink intake, scientists were able to distinguish calcium intake and excretion and determine the total amount used by their bones.

Many of the LMS research facilities were cross-disciplinary and Douglas Watt's Torso Rotation Experiment was also employed for some of the neuroscience studies, by providing for the first time an opportunity to bridge the gap between space motion sickness and the causes of disorientation and nausea on Earth. It was hoped that this could help scientists to learn more about the problems associated with postural disorders and vertigo leading to falls and broken bones. The device precisely tracked the positions of the astronauts' eyes, heads and upper bodies as they went about their everyday activities.

The most important observations came shortly after entering orbit and they reported symptoms associated with adaptation to the microgravity environment. Voluntarily fixing the head to the torso with a neck brace has acquired the name 'torso rotation' because the subject has to turn their entire body in order to move their head. On Earth, this gradually leads to motion sickness in an example of deliberate 'egocentric' motor strategy, during which the subject concentrates on a body frame of reference, rather than an 'external world' reference. Similar motor strategies are often adopted by astronauts, exacerbating the onset of space sickness symptoms.

''The findings will make a contribution to a further understanding, counter-measures and rehabilitative programmes for not only astronauts, but also for people in hospitals on Earth,'' Thirsk told reporters in Toronto during a space-to-ground news conference on 30 June. ''With the information we can figure better ways to keep people in space healthier and fight off muscle and bone degeneration and also use the information on Earth.''

Another device used as part of the neuroscience research was a piece of headgear for the Canal and Otolith Integration Studies, which investigated the impact of microgravity exposure on the vestibular system of the inner ear and resultant changes in eye-hand-head coordination. Throughout the experiment, astronauts wore high-tech modified ski goggles, which carefully tracked their eye and head motions as they watched a series of illuminated targets. Typically, they remained either in a fixed position on the bicycle ergometer or 'free-floating' in the Spacelab module and the targets displayed themselves across the inner surface of the goggles.

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