The International Space Station (ISS) is a unique laboratory operating in low-Earth orbit. Over the past 20 years, more than 3,000 investigations from researchers in 108 countries have been accomplished aboard the orbiting facility. In the early days of ISS assembly, research took place at a more modest level than today. Delays in the launch of the Zvezda Service Module to July 2000 slipped the overall ISS assembly sequence, including the arrival of the Destiny Laboratory module, the cornerstone of US research activities aboard ISS, to February 2001, with the first research facilities arriving shortly afterwards. To get a jump start on conducting research aboard ISS as early as possible, mission managers approved the use of limited resources on the STS-106 mission in September 2000 to launch the first three NASA-sponsored science experiments.
Left: ISS as it appeared to the STS-106 crew in September 2000. Right: The crew of STS-106, front left to right, Malenchenko, Wilcutt, and Altman; rear left to right, Burbank, Lu, Mastracchio, and Morukov.
Space shuttle mission STS-106 lifted off on the morning of September 8, 2000, with its seven-person crew of Commander Terence W. Wilcutt, Pilot Scott D. Altman, and Mission Specialists Edward T. Lu, Richard A. Mastracchio, Daniel C. Burbank, Yuri I. Malenchenko, and Boris V. Morukov. The mission was dedicated to resupplying and outfitting ISS ahead of the first expedition crew’s arrival and therefore had little extra time or space for science payloads. To ease the integration process, the three experiments chosen all had previous flight experience on space shuttle missions, required little crew time, and used little of the available stowage on ascent. One of the experiments would remain in the shuttle middeck throughout the shuttle mission as a so-called sortie payload, a second required only for a crewmember to transfer it to a quiescent location aboard ISS, and the third was passive stowage only, prepositioned on ISS to be operated once the Expedition 1 crew arrived.
Left: Morukov operating the CGBA in the shuttle middeck. Middle: Wilcutt operating the CGBA. Right: CGBA Isothermal Control Module.
The sortie payload consisted of a Commercial Generic Bioprocessing Apparatus (CGBA), a single middeck locker sized apparatus that had flown multiple times on previous space shuttle flights. The CGBA, built by Bioserve Space Technologies at the University of Colorado in Boulder, provided automated processing for biological experiments, minimizing crew interactions to activation, periodic health checks, and deactivation. On STS-106, the CGBA contained the Isothermal Containment Module (ICM) to provide temperature control to the two experiments within the unit. One experiment, Synaptogenesis in Microgravity led by Principal Investigator (PI) Haig Kashishian of Yale University in New Haven, Connecticut, used seven Gas Exchange-Group Activation Packs (GE-GAPs) to house and control the development of Drosophila melanogaster, or fruit flies. The ICM automatically controlled the GE-GAPs through a preset temperature profile during the mission. The experiment, previously flown on STS-93 in 1999, sought to better understand development of the nervous system of fruit flies in microgravity. The second CGBA experiment, Kidney Cell Gene Expression led by PI Timothy G. Hammond of the Durham Veterans Medical Center in Durham, North Carolina, used a single Generic Bioprocessing Apparatus (GBA) in the ICM. The purpose of the experiment, previously flown on STS-90 in 1998, was to study how microgravity affects the gene expression of proteins in cultured kidney cells. The CGBA functioned normally throughout the flight, but unexpected temperature excursions in the two experiments made interpretation of the results problematic.
Left: Student preparing samples for the PCG-EGN Dewar experiment. Middle: Still from a video of Lu transferring the PCG-EGN into the Zarya module. Right: PCG-EGN Dewar stowed in Zarya.
The first passive science experiment placed aboard ISS was the Protein Crystal Growth-Enhanced Gaseous Nitrogen (PCG-EGN) Dewar. Alexander McPherson of the University of California at Irvine was the PI for this experiment that had flown seven times during the Shuttle-Mir Program. The day before launch, flash-frozen samples of 21 different protein solutions in capillary tubes provided by four investigators were loaded into the Dewar, a vacuum-jacketed container similar to a large thermos bottle with an absorbent inner liner saturated with liquid nitrogen. Middle and high school students from Alabama, California, Florida, and Tennessee helped load about 150 of the 500 samples. The Dewar rode into orbit in the shuttle middeck, and once the hatches to ISS were open, Lu transferred the Dewar to a quiescent place in the Zarya module. Over time, the liquid nitrogen boiled off, the frozen samples thawed, and the proteins crystallized out of solution. Without the disturbing influence of gravity, investigators hoped to grow larger and purer crystals to allow more detailed understanding of their structure. The Dewar was returned to Earth by the next space shuttle mission to visit ISS, STS-92 in October 2000, after spending 46 days in space. The PCG-EGN Dewar experiment subsequently flew four more times aboard ISS.
Left: MACE-II experiment floating in the Unity Node 1 module. Middle: Shepherd operating MACE-II in Unity during Expedition 1. Right: Helms operating MACE-II during Expedition 2.
The third experiment launched on STS-106 was the Middeck Active Control Experiment-II (MACE-II) led by PI R. Rory Ninneman of the U.S. Air Force Research Laboratory in Albuquerque, New Mexico, with a collaborating team at the Massachusetts Institute of Technology in Cambridge, Massachusetts, led by David W. Miller. The experiment, previously flown as MACE-I on STS-67 in 1995, sought to demonstrate algorithms that future satellites can use to reduce certain stresses such as vibrations experienced during launch or during orbital maneuvers. The multi-body platform test article, the structure of the MACE-II hardware that was tested, had four 1-inch-diameter struts connected to five nodes. During operations, it was free-floating but loosely tethered in the module. The entire platform had 20 separate sensors that monitor vibration. During STS-106, the MACE-II experiment launched as passive stowage in the Spacehab module and the crew transferred it into the Unity Node 1 module to await the arrival of the Expedition 1 crew. That crew’s commander, William M. Shepherd operated MACE-II near the end of his mission and since he wasn’t able to complete all the required sessions, managers decided to leave it on orbit for Expedition 2 Flight Engineer Susan J. Helms to complete the experiment. The hardware returned to Earth aboard STS-105 in August 2001.
The quest for knowledge continues…