Primary payloads are SPACEHAB-4, a commercially owned and operated laboratory module containing 12 experiments, mostly in commercial space product development; the Spartan 207/Inflatable Antenna Experiment (IAE), which includes a free-flying carrier and an attached antenna that will be inflated and later jettisoned after operations; and Technology Experiments for Advancing Missions in Space (TEAMS), a set of four space technology experiments.

Scheduled as part of the Spartan 207/IAE and TEAMS investigations are a total of four rendezvous operations with two research satellites -- the most ever during a single Space Shuttle flight.

The crew also will conduct and oversee several secondary investigations in the fields of technology demonstration, protein crystal growth and biological processes.

More than 90 percent of the payloads on this 77th Space Shuttle flight are sponsored by NASA's Office of Space Access and Technology through its Commercial Space Centers and their industrial affiliates.

The 11th flight of Endeavour (OV-105) will begin with liftoff from Pad B, Launch Complex 39. Endeavour will ascend to an orbital insertion altitude of 153 nautical miles (283 kilometers/176 statute miles) at a 39-degree inclination to the equator. The planned 10-day mission is scheduled to end at KSC's Shuttle Landing Facility.

Five experienced space flyers, all with military experience, and one rookie comprise the STS-77 crew.

The mission commander is John H. Casper (Col., USAF), who will be making his fourth flight. The former Vietnam War combat pilot has flown three times before on the Space Shuttle, as pilot of STS-36 in 1990 and as commander of STS-54 in 1993 and STS-62 in 1994.

Pilot Curtis L. Brown Jr. (Lt. Col., USAF) will assist Casper at the flight controls. The former Air Force instructor pilot and test pilot flew on two previous Shuttle missions as pilot, STS-47 in 1992 and STS-66 in 1994.

Mission Specialist Andrew S.W. Thomas, the only space flight rookie on the crew, will serve as payload commander. The South Australian native was leader of the program for microgravity materials processing in space at NASA's Jet Propulsion Laboratory before joining the astronaut corps.

Mission Specialist Daniel W. Bursch (Cmdr., USN) will make his third space flight. The former Navy flight instructor and strike operations officer previously flew as a mission specialist on STS-51 in 1993 and on STS-68 in 1994.

Mission Specialist Mario Runco Jr. also will make his third trip into space. A former New Jersey state trooper and Navy fleet environmental services officer, Runco was a mission specialist on STS-44 in 1991 and on STS-54 in 1993.

Canadian Space Agency astronaut Marc Garneau will make his second space flight. A former captain in the Canadian Navy and deputy director of the Canadian Astronaut Program, Garneau was the first Canadian in space when he flew as a payload specialist on STS 41-G in 1984.

Starting with the last Shuttle mission, STS-76 in March, NASA is now leasing a SPACEHAB module to resupply the Russian Mir Space Station during Phase 1 of the International Space Station program. While the single module was used for STS-76, subsequent resupply missions are expected to use the new SPACEHAB double module. The double modules will carry supplies, equipment, water and some experiments on two other Shuttle-Mir docking missions targeted for later this year.

On STS-77, the SPACEHAB Space Research Laboratory single module will carry about 2,905 pounds (1,318 kilograms) of experiments and support equipment for commercial payloads in the areas of materials science and life science. The astronauts will try to grow high-quality crystals of semiconductor and optical materials in two furnaces, the Commercial Float Zone Furnace and the Space Experiment Facility. The SPACEHAB module will be activated on Flight Day One.

The Spartan will serve as a platform for the antenna, which at full inflation, is roughly the size of a tennis court. The lens-shaped antenna has a diameter of about 48 feet (14.6 meters) and is mounted on three 92-foot (28-meter) struts attached to the Spartan spacecraft.

The experiment is designed to validate the deployment (i.e., inflation) and the performance of a large inflatable antenna during a 90-minute test. The Spartan 207 with the attached IAE will be released from the payload bay by the RMS on Flight Day 2. At that time, the IAE will be roughly the size of a large kitchen table. After the antenna is inflated like a balloon, and on-orbit measurements are taken, the Spartan carrier will jettison the IAE; the next day, Endeavour will rendezvous with Spartan and its robotic arm will retrieve and re-berth the spacecraft in the orbiter's cargo bay.

Inflatable components like the antenna could significantly reduce the cost, while increasing the reliability, of deployable structures in space.

The experiments are:

*Global Positioning System (GPS) Attitude and Navigation Experiment (GANE) to assess the degree of accuracy that the GPS can be used to determine the attitude of a space vehicle. The International Space Station will use GPS for position, velocity, time information and attitude determination.

*Vented Tank Resupply Experiment (VTRE) to test improved methods for in-space refueling. The results of this investigation will be incorporated in future designs of spacecraft liquid storage tanks. This experiment also has applications to the space station.

*Liquid Metal Thermal Experiment (LMTE) to evaluate the performance of liquid metal heat pipes in microgravity. The heat pipes used in this experiment are designed to operate at 300 to 1,000 degrees Celsius. The data obtained will be used to design thermal management devices for future space systems.

*Passive Aerodynamically-Stabilized Magnetically-Damped Satellite (PAMS) to demonstrate the principle of aerodynamic stabilization, a method of positioning a satellite in a specific orientation while in low Earth orbit. Aerodynamic stabilization could lead to satellites that are more cost-effective and reliable, and less complicated. PAMS consists of a small deployed satellite and a measuring system. The satellite will be deployed by ejection from a canister in the payload bay on Flight Day 4. Endeavour is scheduled to rendezvous with the satellite three times -- on the day of deployment and on Flight Days 7 and 8 to perform experiment operations.

The Tank Pressure Control Experiment/Reduced Fill Level (TPCE/RFL) experiment, will investigate pressure control in on-orbit storage tanks containing cryogenic propellants and life support fluids. The tank experiment will be in a Get Away Special (GAS) canister, along with 11 other self-contained payloads in canisters mounted on a Get Away Special Bridge Assembly.

A Metallic Thermal Protection System (TPS) experiment, mounted on the outside of the orbiter, will test a type of protective coating for reusable launch vehicles that is lightweight and durable in heavy rain.

In-cabin payloads include the Aquatic Research Facility (ARF), a joint NASA and Canadian Space Agency project to study small aquatic organisms; and Biological Research in a Canister (BRIC) which will focus on the tobacco hornworm during metamorphosis.

Other experiments are the Crystal Growth by Liquid-Liquid Diffusion investigation that will grow protein crystals by diffusing one liquid into another; and the National Institutes of Health-C7 (NIH-C7) experiment to evaluate the effects of space flight on muscle and bone cells from chicken embryos.