A miniSpacelab mission 117

crystals produced on Earth is that the gravitational factors, such as sedimentation and convection, can lead to imperfections in the crystalline structure; such imperfections and their causes are largely side-stepped in a microgravity environment. Overall, Ivins and Low conducted more than 120 protein experiments during the course of the STS-32 mission.

Another of Ivins' responsibilities was the American Flight Echocardiograph (AFE), an off-the-shelf ultrasound device specially modified for the Shuttle. It could non-invasively generate three-dimensional, cross-sectional images of the heart or soft tissues and display them on a CRT screen. Previously flown in April 1985, it was hoped that the echocardiograph might lead to the development of new counter-measures for cardiovascular changes experienced during spaceflight. It was also used in conjunction with another experiment called Lower-Body Negative Pressure (LBNP), a collapsible set of 'trousers' that drew fluids into the legs to counteract the adverse effects of returning to Earth's gravity.

Other experiments included studies of whether the circadian rhythms - daily repeating 'biological clocks' - of pink bread mould persisted in the absence of terrestrial gravity. Samples of the mould were kept in darkness inside a middeck locker and were examined by the astronauts 10 hours after launch, midway through the mission and shortly before re-entry. The results generally indicated that the mould's circadian rhythms did indeed persist in space, although its biological clock may have been affected and 'reset' by daily repeating changes in cabin temperature and carbon dioxide levels on Columbia's middeck.

Another interesting experiment of note has been described by Wetherbee as ''kind of a sextant in reverse'', known as the Latitude-Longitude Locator, or 'L-cubed'. This had its genesis in October 1984, during Challenger's STS-41G mission, when Australian-born oceanographer Paul Scully-Power observed many interesting features from orbit, but was unable to plot their exact geographical locations. To address this problem, NASA, in cooperation with the US Department of Defense, began to develop an instrument that could determine a location's latitudinal and longitudinal coordinates from orbit.

During STS-32, this 'L-cubed' instrument was used by crew members to take repeat photographs of a geographical feature every 15 seconds; the data was then fed into an onboard computer, which calculated two possible sets of latitudinal and longitudinal coordinates. The crew, by knowing whether the target was 'north' or 'south' of their flight path, could then determine which set was correct. The instrument, which utilised a modified Hasselblad large-format camera with a wide-angle lens, proved extremely successful.

Despite the impressive nature of the flight, it was not entirely smooth sailing. On 11 January, before the LDEF retrieval, some 7.5 litres of water oozed from a leaking dehumidifier on the middeck into a compartment where the air-purification equipment was kept. The astronauts switched the leaky unit off and used a backup, to which Brandenstein joked, ''We get the plumber-of-the-year award, but not the housekeeper-of-the-year award.'' They then vacuumed up the waste water and dumped it overboard.

A more serious problem arose as the crew slept during the night of 14 January, when Brandenstein was awakened by Mission Control following indications of a problem with one of the IMUs that kept track of Columbia's acceleration. The device was reset and worked normally, but Al Pennington pointed out that permanent problems with the unit could lead to an early end to the mission. Another key factor in a possible early landing was the weather outlook at Edwards, which was predicted to feature overcast skies and a chance of snow flurries on 17 and 19 January.

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