A Final Farewell to Mir

Commander Charlie Precourt brought the Space Shuttle Discovery in for a perfect landing at the Kennedy Space Center at 2:00 p.m. EDT (1800 UTC). A strong high pressure system over the eastern Gulf of Mexico resulted in unusually good weather for a Florida afternoon. Even then, the passage of the afternoon sea breeze presented forecasters with a challenge. Winds were switching from southwest to northeast just 25 minutes before the de-orbit burn decision . . . and were just a few knots under the 15 knot crosswind limit for a daylight landing. The sea breeze and strong afternoon heating produced scattered low clouds. These clouds increased in the vicinity of the runway, but stayed in the 2/8 coverage range (below the limit of 5/8). Excellent weather reconnaissance reports from astronaut pilot Ken Cockrell aided the SMG forecasters.

Discovery's nine-plus day mission culminated 977 total days spent in orbit by the seven U.S. astronauts who stayed aboard Mir since the Shuttle-Mir program began. Mission Specialist Andy Thomas was the last visitor; he was brought back after four and a half months onboard Discovery. Another highlight was Mission Specialist Franklin Chiang-Diaz completing a record - tying sixth space flight and 1,269 hours in total space shuttle flight time . . . a record for U.S. astronauts.

The Alpha Magnetic Spectrometer overcame some communications problems to search for anti-matter and dark matter in space. This will help probe further into the Big Bang theory of the origin of the universe.

The Space Shuttle Discovery launched from the Kennedy Space Center on June 2, 1998, at 6:05 p.m. EDT (2205 UTC). Thanks to a strong high pressure system over Florida and the Gulf of Mexico, the weather was unusually good. There were a few low clouds (5,500 feet). The 14 knot crosswinds from a brisk southwest wind were just within limits for the RTLS (Return to Launch Site for an abort requires crosswinds of 15 knots or less). The wind forecast was a little tricky since a potential sea breeze could have caused varying winds for RTLS. Unlike prior days in the week, the sea breeze developed too late to make it inland to the Shuttle Landing Field (SLF). Weak high pressure over the Transoceanic Landing (TAL) sites in Spain and Morocco made them "weather go" as well. These good weather conditions took some of the pre-launch pressure off the 10-minute launch window.

The SMG Lead Forecaster for STS-91 was Steve Sokol, working his 80th mission overall (15th as mission lead). The TAL Forecaster and Assistant Lead was Wayne Baggett. The Lead Techniques Development Unit (TDU) meteorologist was Tim Oram.