The Spaceflight Meteorology Group

Postflight Mission Summary for STS-94

July 31, 1997

Space Shuttle Columbia landed at the Shuttle Landing Facility (SLF), Florida at 10:47 UTC, on Thursday, July 17, 1997, after the seven person crew successfully completed their "virtually perfect scientific mission" of sixteen days. STS-94 was the reflight of the April, 1997, STS-83 Mission, which was shortened prematurely due to a fuel cell problem.

Weather for launch day proved to be exciting. Attempting a launch in Florida in the middle of the afternoon in July always presents a challenge. Surface high pressure over Florida and the Gulf of Mexico persisted as a weak upper level trough remained over the eastern US. Winds aloft were generally westerly. Thunderstorms developed along the western coast of Florida and moved east southeastward. Cumulus fields developed as surface heating increased over the land. Showers and thunderstorms developed over central Florida in the late morning and early afternoon hours. As launch time approached these thunderstorms continued moving east southeastward near the southwest portion of the 20 NM circle surrounding the SLF. Rainshowers developed within a hour of launch northwest of the SLF just beyond the 20 NM circle. After the weather recon pilot reported this activity was dissipating and returns from the Melbourne WSR88D confirmed no further development, the RTLS forecast was amended at 17:50 UTC to remove "TSRA WI 20 NM". The count was picked up at the T-9 Minute hold. Two minutes from launch, forecasters at the Range Operations Control notified SMG that the Lightning Detection And Ranging (LDAR) system was detecting lightning from a cell approximately 18 NM south southwest of the SLF. SMG notified the Flight Director that this activity was expected to continue moving away from the SLF and would not impact RTLS.

At the TAL sites a weak surface low pressure area was present to the southwest of Spain and was expected to remain nearly stationary and produce little weather for Ben Guerir, Morocco. Surface winds did approach crosswind limits there, but these limits were never exceeded. At Banjul, The Gambia, the other TAL site, a low cloud ceiling developed for about one hour during the launch count, but moved out of the area. Convective complexes developing over central Africa were expected to produce a threat of "TSRA WI 20 NM" for Banjul. As the launch count progressed, these thunderstorms remained beyond the approaches to Banjul, and were removed from the forecast. The weather recon pilot reported "HAZE aloft, but GO, with a reduced slant range visibility.

Columbia lifted off at 18:02 UTC, after a twelve minute wait (due to weather concerns) in the opening of the two and one half hour launch window. With ample high level moisture present, pileus clouds were observed around the vehicle as it lifted through the 30,000 foot level.

The Microgravity Lab was flown for 16 days. The mission, described by the NASA Shuttle Program Manager, Tommy Holloway, as "a virtually perfect scientific mission," far exceeded the scientific community’s data collection expectations.

Touchdown of Columbia occurred at the Shuttle Landing Facility (SLF), KSC, Florida at 10:47 UTC, July 17, after sixteen days in orbit. The initial weather concern was for visibility restrictions due to fog. With light winds and high dewpoint temperatures a risk of fog development existed. As on launch day, winds aloft were blowing offshore. Showers in the Gulfstream were persistent. Weak boundaries from the land breeze and out-flow from earlier convection collided and produced a shower near Patrick AFB that developed into a short-lived thunderstorm three hours prior to the de-orbit burn decision. The land breeze continued moving offshore. At 07:50 UTC, SMG updated the forecast to remove fog, due primarily to sufficient wind velocity and mixing in the surface-to-500 foot layer. However, weak showers persisted offshore through the final hour leading to the de-orbit burn decision. At 09:30 UTC, just before the de-orbit burn decision, SMG updated the forecast to include "showers 20 to 30 NM offshore." The Flight Director determined that this would not produce an impact to landing and gave a "GO" for the de-orbit burn at 09:36 UTC. Columbia touched down without incident. Visibility at landing was 8 miles in BCFG (Fog Patches). Weather remained favorable through post landing operations.

Lead Meteorologist for STS-94 was Dan Bellue. Tim Garner was the Assistant Lead, and Mark Keehn worked as the Lead Techniques Development Unit (TDU) Meteorologist. Richard Lafosse worked as the Radar Meteorologist. This marked the fourth time that this team of meteorologists has worked a shuttle launch and landing together.

Submitted by:

Dan G. Bellue and Frank C. Brody