Hot Science In A Warm

As the FREESTAR experiments commenced operations, the Spacehab module was also a hive of activity as two shifts of astronauts activated and began their extensive programme of around-the-clock research. Only the most minor of problems, it seemed, was troubling Columbia herself: one of two heaters in a cryogenic fluid storage tank in the payload bay refused to work and part of the intercom between the module and the crew cabin exhibited difficulties.

Then, on the afternoon of 20 January, managers noticed an electrical 'spike' in one of two dehumidifiers used to collect and distribute water produced from condensation buildup in Spacehab. An identical system had sprung a leak the night before and was shut down, prompting Willie McCool to ''stop talking and start mopping''. A valve was reconfigured to allow cool air from Columbia's crew cabin to flow into the module, which stabilised the temperature level at a balmy 29 Celsius. Later in the mission, an air duct was routed into Spacehab to bring this down to around 22 Celsius.

''Even though the air temperatures are a little bit warmer in the hab right now than they would normally be, it's not really a factor for the crew,'' said Mission Operations Manager Phil Engelauf. ''It's really not even outside their comfort level.'' In fact, the temperature rise in the module had even drawn envious comments from scientists at the Goddard Space Flight Center, who told the astronauts that the overnight forecast in Maryland was for a 'low' of 8 degrees and a wind chill of minus 5 degrees. Even Cape Canaveral had seen snow flurries on 17 January.

Despite the slight rise in temperature, the research inside Spacehab continued at breakneck pace, although the astronauts had to move some of their life sciences gear over to Columbia's middeck to keep it sufficiently cool. One of the most important pieces of equipment on board STS-107 was ESA's Advanced Respiratory Monitoring System (ARMS), which required the crew to participate in an extensive series of breathing exercises to measure their cardiac output, with particular focus on the critical first few hours in microgravity. Its first measurements were taken just six hours after launch.

''They're looking specifically at the changes in respiratory or lung function when patients have to be on their backs for extended periods of time,'' said Laurel Clark. ''In fact, there's some good evidence that patients in intensive care units would be better off on their stomachs as opposed to their backs. This entails a huge amount of

Zhou Weijia Wisconsin

Demonstrating the 'roominess' of the new Spacehab Research Double Module, Kalpana Chawla tends experiments during her shift as part of STS-107's Red Team. Note the foot restraints covering the 'floor' of the laboratory.

overhead to take care of them that way, but certainly if there's much better oxygen exchange and lung function, then it's worth that overhead. They've been studying us in different positions, on our stomachs and on our backs, studying the air exchange.''

All four 'science crew' members - Anderson, Brown, Clark and Ramon - worked with the ARMS device during their respective shifts throughout the first two-and-a-half days of the mission, acquiring data both at rest and during periods of moderate to medium-high exercise on a stationary bicycle ergometer. The only problems were a higher-than-anticipated noise from one of its two gas analysers, which was later resolved, and a temporary 'lock-up' of its computer. This initially led to the cancellation of one of the planned pulmonary tests, although a rescheduling of priorities succeeded in recovering it and performing it satisfactorily.

Even 10 days into the mission, with almost a week to go before Columbia's landing, ARMS investigators were lauding a 100% success rate for their device. They did, however, stress that most of the critical data would not be complete until a battery of tests could be conducted on the astronauts, beginning a few hours after their 1 February touchdown back in Florida . . .

Meanwhile, in the field of biological research, cell cultures were being grown as part of efforts to better understand their genetic characteristics and ultimately combat prostate cancer and improve crop yields. Many of the life science and biological studies were sponsored by European and Canadian investigators, while the German space agency provided an experiment to observe the development of gravity-sensing organs in fish and students from across the globe explored the effects of microgravity on spiders, inorganic crystals, silkworms, bees and ants.

The Advanced Protein Crystallisation Facility (APCF), which had ridden several previous Spacelab missions, supported several hundred samples of key proteins, while the Biobox payload cultivated specimens of mammalian cells as part of four experiments provided by Belgian, French and Italian researchers. Both were supplied by ESA, as was Biopack, which explored the influences of acceleration and high-energy cosmic radiation on biological processes.

Flying commercially after several years of tests was Astroculture in Columbia's middeck, which was being used on STS-107 to investigate whether roses grown and nurtured in low-Earth orbit could produce new fragrances. As part of a study sponsored by perfume giant International Flavours and Fragrances (IFF), a tiny rose known as 'Overnight Scentsation' had flown on board STS-95 in October 1998 and yielded a fragrance which the company's Braja Mookherjee called ''a very green, fresh rosy note''. Fibres were used to 'collect' the scent for post-flight analysis and the fragrance was later incorporated into a new perfume known as 'Zen'.

On STS-107, two different plants - a rose and an Asian rice flower - were housed inside Astroculture and, as of 24 January, their growth was proceeding well. ''It's truly fascinating to see two flower plants doing very well up there,'' said project manager Weijia Zhou of the Wisconsin Center for Space Automation and Robotics, which worked jointly with IFF on the study, adding that ''the [space-grown] rose is a mild and pleasant kind of aroma; the other [Earth-grown] is strong''.

Elsewhere, combustion scientists were continuing the highly successful research begun on Columbia's MSL-1 missions in 1997 by reflying their versatile

Combustion Module, which was primarily under Kalpana Chawla's supervision. She had proved to be a rising star in NASA's Astronaut Office since her first bittersweet journey into space more than five years earlier. She had been ultimately exonerated from blame for the botched deployment of the Spartan-201 satellite during STS-87, and perhaps to highlight his own confidence in her abilities, Rick Husband had nominated her as the flight engineer for STS-107. Her performance was nothing short of exemplary.

''We've been busier than I ever imagined,'' she told Mission Control on 18 January, ''since things do take longer up here.'' Her duties with the Combustion Module encompassed three separate experiments: Paul Ronney's SOFBALL study of flame balls in microgravity, Gerard Faeth's Laminar Soot Processes (LSP) analysis of the formation and behaviour of soot and a new investigation known as 'Mist'. The latter was intended to investigate the use of fine water mists in firefighting, although its first run on 27 January encountered problems when it sprung a leak.

After repairing a faulty seal, then struggling to introduce mist into the experiment's chamber, Chawla began more than a dozen Mist experiments. During one of the tests, the pace of which had been deliberately increased to make up for lost time, video footage revealed an impressive slowing-down, elongation and 'wiggling' of one particularly weak flame. ''[Mist studies] how you can use water [vapour] to better extinguish fires,'' said Brown, adding that the combustion experiments on STS-107 were the second step towards a fully fledged Fluids and Combustion Facility for the space station.

Ronney and Faeth were also more than happy with their studies. ''It's been a great experiment to date,'' Ronney told journalists on 22 January as the facility's cameras detected and videotaped faint amounts of light and heat emitted by flames just 5 to 10 mm in diameter. Even taking account of the earlier MSL-1 research, he added STS-107's SOFBALL studies had set at least three new records: the weakest flame ever burned (in orbit or on Earth), the least amount of fuel mixed with air and - at more than 81 minutes - the longest-lived flame ever burned in space.

''I guess you could also say maybe the most excitement by a combustion researcher,'' Ronney joked. ''Is that a record, too?'' Flame balls had first been theoretically predicted by the Russian physicist Yakov Zeldovich in 1944, but were not seen under experimental conditions until Ronney's drop-tower tests four decades later. During STS-107, no fewer than 39 tests were performed, utilising 15 different fuel mixtures and triggering 55 flame balls which burned for a total of six-and-a-quarter hours. To minimise disturbances, Columbia's thrusters were disabled and the orbiter kept in 'free-drift' while the OARE monitor carefully measured acceleration levels.

It was hoped that SOFBALL data could lead to cleaner and more efficient car engines, as well as improving fire safety. It also gave the crew the opportunity to 'name' a few of the hardier flame balls. ''[I'm calling this one] Howard,'' deadpanned Dave Brown as the mission's final week drew to a close. ''After that, everyone started naming them,'' added Ronney. ''It was fun. It also helped us to keep track of some of the strange things we saw.'' Two balls which flew around in a spiral, DNA-like pattern were dubbed 'Crick and Watson' after the two Nobel Prize-winning biophysicists.

One of the largest flame balls was named 'Zeldovich' and another honoured Paul Ronney himself, although, as the principal investigator pointed out with a chuckle, ''it turned out to be small and short-lived ... a wimp!'' Overall, the flame ball studies were an outstanding success. ''We didn't think flame balls could last for more than a few minutes,'' said Ronney of the MSL-1 studies, ''but we were wrong. Many of them were still burning when SOFBALL's computer automatically ended the test. We needed more time." That additional time was provided during the STS-107 experiment runs.

''Before the mission began, I said I wanted to send a flame ball around the world. 'Kelly' almost made it,'' Ronney said of the longest-lasting of all flame balls, which burned for 81 of the 90 minutes needed for Columbia to circle the globe. ''Kelly's experience is a fascinating example of group dynamics among flame balls. She was created, one of nine flame balls, in a gaseous mixture of hydrogen, oxygen and sulphur hexafluoride. All the others began drifting around the chamber . . . competing with one another, while Kelly remained motionless at the centre. Before long, the others were exhausted; they had drifted too close to the walls and winked out. Kelly was left alone with a chamber full of fuel.''

Other important experiments included Buddy Guynes' Mechanics of Granular Materials (MGM), which sought to test 'sand columns' under microgravity conditions that could not be mimicked on Earth. ''The possibility of retirement is appealing to me, but I want to work for a good while yet,'' said Guynes, a researcher from NASA's Marshall Space Flight Center. ''I'm expecting exciting results from the mission and would like to have a hand in getting the good news out to the public.'' The experiment looked at how environmental changes could drastically change the properties of a bulk granular material.

The obvious household example of this phenomenon is a packet of coffee, which, originally brick-solid when packed, becomes much softer and easily shifted once it is opened and air is admitted. ''Before that air comes in,'' explained Guynes, ''you can almost use that coffee [package] like a hammer. As soon as you let air in, it gets real loose. The [thixotropic] soil [effects] you see in an earthquake can be similar, especially if there's water around. Water is a lubricant between the grains. When they're shaken, they also get loose.''

The strength of soils comes from the friction and geometric 'interlocking' between the faces of individual grains; but this can also introduce weaknesses as their craggy surfaces form small voids and make them behave like liquids when moisture and air are trapped. As external pressure increases, intergranular pressures drop and soften the material, eventually liquefying it. During this process of liquefaction, buildings can sink and tilt, bridge piers can move and buried structures can float. On STS-107, three columns of sand were 'squeezed' between tungsten plates in a water-filled Lexan jacket.

Previous MGM flights in 1996 and 1998 had already yielded a number of insights into soil mechanics and behaviour and it was hoped that the experiments on Columbia's mission would enable scientists to design better models of soil movement under stress. This could eventually lead to new ways of strengthening building foundations, managing undeveloped land and handling powdered and granular materials in chemical, agricultural and other industries. ''We might end up changing our building techniques,'' Guynes speculated. ''This is one of the things NASA is doing that has a very strong application for the guy on the street.''

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