The middeck area of the Space Shuttle Orbiter's pressurized crew segment is the most cost-effective place aboard the Shuttle for conducting crew-tended scientific and commercial microgravity experiments. However, mid-deck locker space for experiments is very limited.

To meet a new for more experiment facilities per flight, SPACEHAB, Inc., Arlington, Virginia developed the SPACEHAB Space Research Laboratory pictured. Carried in the Orbiter's payload bay and accessed through an airlock, the SPACEHAB laboratory is a pressurized facility that roughly doubles the Orbiter's habitation volume and quadruples the volume available for crew-tended payload hardware. At right, the laboratory is shown in the Orbiter's payload bay on flight STS-63; the photo was taken by an astronaut perched high above the Orbiter on the remote manipulator arm.

Two of the basic SPACEHAB modules were built and certified for Shuttle flight in a development program financed entirely with private capital. McDonnell Douglas Aerospace conducted design, development and construction of the modules under contract to SPACEHAB, Inc. SPACEHAB pays NASA for launch services and leases experiment space to U.S. and international private industry, universities, research institutions, and government agencies, including NASA.

The laboratory has flexible accommodations wherein payloads can be carried in racks and lockers and externally on the flat rooftop. Equipped with the necessary subsystems for power, environment control and life support, communications and data systems, the basic module is 13.5 feet in diameter, nine feet long, has 1,100 cubic feet of pressurized volume and a 4,800-pound payload capacity.

The SPACEHAB Space Research Laboratory made a successful Space Shuttle debut aboard STS-57, Orbiter Endeavour, in June 1993. On that occasion, the module carried 22 experiments sponsored by more than 25 U.S. companies, NASA, a network of universities and research organizations, and the European Space Agency.

In February 1994, the laboratory went aloft on its second flight aboard STS-60, Orbiter Discovery. Once again it demonstrated successful performance, housing 13 commercial development experiments, including crystal growth research aimed at development of improved semiconductors, and an investigation of the structure of human insulin crystals directed toward possible improvement in the treatment of diabetes.

SPACEHAB's third flight - also successful - was on STS-63, Orbiter Discovery, in February 1995. On SPACEHAB-3, SPACEHAB, Inc., introduced innovations to reduce significantly the demand on crew time: a video switch for trimming the time astronauts spend controlling video equipment and an experiment interface in the SPACEHAB telemetry system that reduces crew time in downlinking experiment data. Another new feature is a pair of 12-inch diameter windows on the roof of the module; one window has a NASA docking camera to assist in Shuttle/Mir rendezvous docking.

SPACEHAB, Inc. has developed a "double" module to increase its payload-to-orbit capacity and to provide greater flexibility in a mixed configuration, the forward half for locker and rack science experiments and the aft half for cargo/supply support of Shuttle/Mir missions.

Shown above, the double module is capable of carrying 10,000 pounds of cargo (experiments and supplies), but it will be constrained to 6,000-pounds on Shuttle/Mir flights because the dockings take place in Mir's high inclination orbit. The double module consists of one of the standard single modules joined together with the SPACEHAB Structural Test Article that was used to qualify the single module. The Italian company Alenia Spazio is preparing the double module and certifying it for flight. It will debut on Shuttle/Mir Mission 4 (STS-79, July 1996) and will also be used on Mir Missions 5 and 6.