Not all of the experiments were housed on the MPESS-mounted payload bay hardware. A new, and potentially important facility - particularly in anticipation of upcoming International Space Station research - was provided in the Shuttle's middeck. Known as the Middeck Glovebox (MGBX), it was developed by Don Reiss of NASA's Marshall Space Flight Center and was essentially a scaled-down, locker-based version of the unit that had for some years been used in the Spacelab module. Equipped with video and still cameras and foot-activated audio-recording gear, it was used on STS-75 to conduct three combustion experiments.
The Middeck Glovebox 263
It was activated late on 22 February, only hours after Columbia reached orbit, and following a test of its cameras and recording equipment, took centre-stage from the 27th. Typically, for each experiment, the crew removed a sample kit from stowage lockers and inserted it through the MGBX door, before tightly sealing the unit. Using gloves, they were then able to manipulate the samples. The three experiments investigated the effect of airflow on flame-spreading characteristics, explored the conditions leading to the ignition of several samples of ashless filter paper and examined the behaviour of soot under microgravity conditions.
On 3 March, Takashi Kashiwagi of the National Institute for Standards and Testing and Principal Investigator of the Radiative Ignition and Transition to Spread Investigation (RITSI) - the filter paper experiment - received a boost in science return thanks to Cheli, who sped up a relatively long process and completed half of a second run ahead of schedule. Early results indicated that flames produced in space differ dramatically from those on Earth. ''They were upside-down,'' exclaimed Kashiwagi, ''completely the reverse of flames one usually sees!''
Another experiment, supervised by Horowitz, was the Forced-Flow Flame-Spreading Test (FFFT), in which he ignited a cylindrical sample of ashless paper, commenting on ''a blue ball moving down the tube'' as he recorded the phenomenon on video. He also informed investigators that he saw ''a yellow flame inside the blue flame that is quite spectacular! I've never seen anything like this.'' All MGBX combustion experiments were completed by 5 March and the crew was instructed to check and evaluate the unit's performance before stowing it away.
''These procedures'', said Glovebox Facility Manager David Jex of NASA's Marshall Space Flight Center, ''will give the Marshall project team a post-operation look at Glovebox performance following a range of combustion experiments performed over the last few days.'' Added Peter Curreri: ''The mix of remote-controlled experiments in Columbia's [payload bay], with the hands-on Glovebox demonstrations in the Shuttle middeck, have proven the compatibility of the two approaches to conducting science in orbit.'' In total, 65 samples, ranging from paper to Teflon, were burned and, according to investigators, gathered more than 125% of the planned scientific data.
Knut Sacksteder of NASA's Lewis Research Center, the Principal Investigator for the FFFT experiment, reported 16 flat and cylindrical paper samples successfully burned, yielding significant variations in flame colour, size, growth rate, airflow speed and fuel temperature. Kashiwagi's RITSI team, meanwhile, observed a new combustion phenomenon known as 'tunnelling flames', which moved along a narrow path rather than 'fanning out' from the burn site. Lastly, NASA Lewis' David Urban, developer of the Comparative Soot Diagnostics (CSD) experiment, tested the effectiveness of two different smoke-detection systems.
Such experiments, said Franklin Chang-Diaz, ''are going to be valuable if we are going to have a reliable fire-detection system'' on the International Space Station. Although Columbia would never visit the orbital complex, her crew did succeed in contacting a team of astronauts who in two weeks would fly to another space station: the Russian outpost, Mir. On the morning of 6 March, Allen spoke to Kevin Chilton, who would command the STS-76 mission to Mir later that month. ''When you get up here,'' Allen joked, referring to TSS-1R, ''if you see anything we left, bring it home for us.''
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