The final shuttle-Mir mission, STS-91 recovered NASA astronaut Andy Thomas from the Mir station and took Russian space chief and ex-cosmonaut Valeri Ryumin to Mir for an inspection tour of the ageing station. This was the first test of the super lightweight Aluminium-Lithium alloy external tank, designed to increase shuttle payload to the Mir / International Space Station orbit by 4,000 kg. At 22:15 GMT Discovery entered an initial 74 x 324 km x 51.6 deg orbit, with the OMS-2 burn three quarters of an hour later circulising the chase orbit. Discovery docked with the SO module on Mir at 17:00 GMT on June 4. NASA equipment was retrieved from the station, and Discovery undocked at 16:01 GMT on June 8, and landed on Runway 15 at Kennedy Space Center at 18:00 GMT on June 12.
On an extremely successful mission the space shuttle Endeavour deployed the 61 metre long STRM mast. This was a side-looking radar that digitally mapped with unprecedented accuracy the entire land surface of the Earth between latitudes 60 deg N and 54 deg S. Sponsors of the flight included the US National Imagery and Mapping Agency (NIMA), NASA, and the German and Italian space agencies. Some of the NIMA data would remain classified for exclusive use by the US Department of Defense.