PCG-STES-MMTP
The PCG-STES-MMTP operated on the International Space Station during Expedition 5. The
experiment used Mitochondrial Metabolite Transport Proteins samples to grow crystals. This
investigation suffered sample loss from the sample pedestals during the mission. Even though
there was a loss of some of the sample, crystals did grow in 4 out of the 28 wells.
Unfortunately, these crystals were too small and poor quality to perform X-ray diffraction.
PCG-STES-MS
The PCG-STES-RGE operated on the International Space Station during Expeditions 6 through
- This mission was launch in November 2002 and was returned in August 2005. This was the
longest running crystal experiment to date aboard the ISS.
PCG-STES-RDP
PCG-STES-RDP operated on ISS during Expedition 5 during 2 separate runs. The experiment
used an engineered RNA enzyme sample to grow crystals. Crystals were not obtained from the
first run of this investigation. This was attributed to using the precipitant MPD (hexylene glycol),
which is now known to evaporate more than expected in the PCAMs. This investigation began
in June 2002 and was concluded in October 2002. During the post analysis, it was discovered
there was an increase in the concentration of magnesium chloride in the samples, which may
have led to the degradation of the samples. (One Year Postflight Report, 2003)
The second run of this investigation began in October 2002 and concluded in December 2002.
The detailed examination of the PCAM trays revealed that tiny crystals had grown in the trays.
They may have been overlooked in the initial examination when the samples were returned to
Earth. It is not known whether the crystals grew in orbit or post-landing. Upon further
examination, it appeared that the samples had been disturbed. An explanation of the
disturbance is that the STES unit had been dropped or jolted during transport with enough
force to displace the samples or shatter crystals.
These experiments lead to an optimization of growing the ribozyme in ground laboratories.
Crystals are now more reproducible. The rate of growth has increased from 4% to 50% (One
Year Postflight Report, 2003).
PCG-STES-RGE
No information gathered.
PCG-STES-SA
Not surprisingly, given the wide array of materials and objectives, some samples did produce
large crystals while other samples produced crystals no better than those produced on Earth.
Yet other samples failed to crystallize at all. Crystals of MnSOD, produced during Expedition 4,
exhibited an 80-fold volume increase when compared to the crystals produced on Earth. The
crystals that were produced in orbit ranged from small, needle-like crystals to large 3-D crystals.
These crystals were used for Synchrotron X-ray analysis, the use of a high-energy, adjustable
particle beam used for crystal diffraction. Through this analysis it was determined that the