Scientist photographs STS- 26 Post-flight (VDA) Vapor Diffusion Apparatus Tray with (PCG) Protein Crystal Growth Samples.

The COS consists of a specially designed (VDA) Vapor Diffusion Apparatus tray with 6 chambers, a video camera for each chamber, a lighting system, and associated hardware. By observing the crystal growth in each chamber, researchers can identify which conditions and concentrations of proteins and precipitants are best for promoting the crystal growth to a particular protein.

Final (VDA) Vapor Diffusion Apparatus Tray adjustments before loading into shuttle.

STS066-13-029 (3-14 Nov 1994) --- On the Space Shuttle Atlantis' mid-deck, astronaut Scott E. Parazynski, mission specialist, works at one of two areas onboard the Shuttle which support the Protein Crystal Growth (PCG) experiment. This particular section is called the Vapor Diffusion Apparatus (VDA), housed in a Single Locker Thermal Enclosure (STES). Together with the Crystal Observation System, housed in the Thermal Enclosure System (COS/TES) the VDA represents the continuing research into the structures of proteins and other macromolecules such as viruses. In addition to using the microgravity of space to grow high-quality protein crystals for structural analyses, the experiments are expected to help develop technologies and methods to improve the protein crystallization process on Earth as well as in space.

On the Space Shuttle Atlantis' mid-deck, astronaut Joseph R. Tanner, mission specialist, works at area amidst several lockers onboard the Shuttle which support the Protein Crystal Growth (PCG) experiment. This particular section is called the Crystal Observation System, housed in the Thermal Enclosure System (COS/TES). Together with the Vapor Diffusion Apparatus (VDA), housed in a Single Locker Thermal Enclosure (SLTES) which is out of frame, the Cos/TES represents the continuing research into the structures of proteins and other macromolecules such as viruses.

On the Space Shuttle Orbiter Atlantis' middeck, Astronaut Joseph R. Tarner, mission specialist, works at an area amidst several lockers which support the Protein Crystal Growth (PCG) experiment during the STS-66 mission. This particular section is called the Crystal Observation System, housed in the Thermal Enclosure System (COS/TES). Together with the Vapor Diffusion Apparatus (VDA), housed in Single Locker Thermal Enclosure (SLTES), the COS/TES represents the continuing research into the structure of proteins and other macromolecules such as viruses.

These Vapor Diffusion Apparatus (VDA) trays were first flown in the Thermal Enclosure System (TES) during the USMP-2 (STS-62) mission. Each tray can hold 20 protein crystal growth chambers. Each chamber contains a double-barrel syringe; one barrel holds protein crystal solution and the other holds precipitant agent solution. During the microgravity mission, a torque device is used to simultaneously retract the plugs in all 20 syringes. The two solutions in each chamber are then mixed. After mixing, droplets of the combined solutions are moved onto the syringe tips so vapor diffusion can begin. During the length of the mission, protein crystals are grown in the droplets. Shortly before the Shuttle's return to Earth, the experiment is deactivated by retracting the droplets containing protein crystals, back into the syringes.

The Thermal Enclosure System (TES) provides thermal control for protein crystal growth experiments. The TES, housed in two middeck lockers on board the Space Shuttle, contains four Vapor Diffusion Apparatus (VDA) trays. Each can act as either a refrigerator or an incubator and its temperature can be controlled to within one-tenth degree C. The first flight of the TES was during USMP-2 (STS-62).