This photograph shows the Instrument Pointing System (IPS) for Spacelab-2 being deployed in the cargo bay of the Space Shuttle Orbiter Challenger. The European Space Agency (ESA) developed this irnovative pointing system for the Spacelab program. Previously, instruments were pointed toward particular celestial objects or areas by maneuvering the Shuttle to an appropriate attitude. The IPS could aim instruments more accurately than the Shuttle and kept them fixed on a target as the Shuttle moved. On the first pallet, three solar instruments and one atmospheric instrument were mounted on the IPS. Spacelab-2 was the first pallet-only mission. One of the goals of the mission was to verify that the pallets' configuration was satisfactory for observations and research. Except for two biological experiments and an experiment that uses ground-based instruments, the Spacelab-2 scientific instruments needed direct exposure to space. The Spacelab-2 mission was designed to capitalize on the Shuttle-Spacelab capabilities to carry very large instruments, launch and retrieve satellites, and point several instruments independently with accuracy and stability. Spacelab-2 (STS-51F, 19th Shuttle mission) was launched on July 29, 1985 aboard the Space Shuttle Orbiter Challenger. The Marshall Space Flight Center had overall management responsibilities of the Spacelab missions.
