On this MSL-1 mission, Long Module 1 carries a number of experiment racks including a test flight of the International Standard Payload Rack which is to be used on Space Station. Rack 12 is the misleadingly named Middeck Glovebox, which used to fly on the orbiter mid-deck but now is in the Long Module, and carries more materials experiments. The OARE Orbiter Acceleration Research Experiment is an instrument attached to the bottom of the cargo bay, which has flown on many previous Columbia missions. It measures the acceleration environment of the Shuttle, which is particularly important on a microgravity experiment mission. It consists of the Hitchhiker avionics box and a Getaway Special type canister containing two experimental heat pipes.
Heat pipes are devices used to passively remove heat from electronics on spacecraft.
Technical problems with the life support systems and thermal control systems continue on board Mir. The carbon dioxide removal system failed on Apr 3. Launch of a supply craft, Progress M-34, with repair equipment for the oxygen systems, is scheduled for Apr 6. A Defense Meteorological Satellite Program weather satellite for the US Air Force was launched on Apr 4 from Vandenberg. The Titan 23G-6 rocket separated from the payload six minutes after launch and delivered the DMSP and its integral Star 37 solid motor upper stage into a suborbital trajectory over the Pacific.