The Spaceflight Meteorology Group

STS-103, the 96th Shuttle mission lifted off from Pad 39-B of the Kennedy Space Center at 00:50 UTC (06:50 CST), December 20th, 1999, into a 28.45� inclination orbit. This was the 27th flight for the Shuttle Discovery and the 3rd servicing mission for the Hubble Space Telescope (HST).

The Hubble Space Telescope had lost a fourth gyroscope in mid November 1999 and although the craft remained safely in orbit, it was placed in a "safe mode" until repairs could be completed. Having fewer than three working gyroscopes precluded any scientific observations, since the telescope has very precise pointing requirements. When three of Hubble's six gyros failed earlier this year, NASA officials decided to move forward the June 2000 Hubble servicing mission. Three gyroscopes must be working to meet the telescope's scientific observational requirements. Other mission servicing activities on the HST included the replacement of a guidance sensor, a new transmitter, the spacecraft's computer, and some degraded insulation.

The crew was led by Curtis L. Brown, Mission Commander and Scott J. Kelly, Pilot. Other crewmembers were Steven L. Smith, Mission Specialist, C. Michael Foale, Mission Specialist, John M. Grunsfeld, Mission Specialist, Claude Nicollier, Mission Specialist (ESA), and Jean-Francois Clervoy, Mission Specialist (ESA).

With the grounding of the shuttle fleet after STS-93, several launch dates were used after the STS-103 mission was slipped from the original September 13, 1999 date to mid-October, then late November, and finally to December:

1st Launch Date - 11 Dec 1999 05:13Z - Saturday PM - Delayed at L-2 Day MMT

2nd Launch Date - 17 Dec 1999 02:18Z - Thursday PM - Delayed 24 hours at Tanking MMT earlier in day

3rd Launch Date - 18 Dec 1999 01:47Z - Friday PM - Weather Scrub

4th Launch Date - 19 Dec 1999 01:21Z - Saturday PM - Delayed 24 hours at 2nd Tanking MMT earlier in day

5th Launch Date - 20 Dec 1999 00:50Z - Sunday PM - On Time Launch

Launch Weather: After several delays including a weather scrub in the launch count, STS-103 had an on-time launch on the evening of the 19th of December at 6:50 PM CST. Weather was relatively benign as mid and high level cloudiness from the Gulf of Mexico streamed over the Florida peninsula. West and northwest winds prevailed keeping the low levels dry and cloud free. A weak frontal boundary had persisted over the Florida panhandle with an associated weak low-pressure center located off of the Carolina coast. The prime Transoceanic Abort Landing (TAL) site was Ben Guerir since weather at Banjul, The Gambia, was �NO GO� due to visibility restrictions caused by smoke and haze from a controlled burn near the airport.

Weather two days earlier had caused a weather scrub as multi-layered clouds, rain, crosswinds, turbulence, and the potential for triggered lightning caused forecasters to issue a NO GO forecast. A weak warm frontal boundary had moved into the mid portions of Florida creating the disturbed weather, which persisted throughout the launch count. The scrub was called several minutes after the opening of the launch window.

Landing Weather: A weak frontal boundary over the Florida panhandle drifted southward during the day, producing an increased pressure gradient over central Florida. No weather was associated with this boundary as it drifted southward and virtually cloudless skies prevailed at the SLF throughout the day. Westerly winds persisted, causing surface winds to go out of limits for cross winds at the de-orbit decision time for the first landing opportunity. Winds subsided as the sun set and the subsequent landing opportunity was observed "GO" at the decision time and forecast "GO".

The mission was cut short by two days because of launch delays and the possible Y2K impact. Landing occurred after almost 8 days in orbit at the Shuttle Landing Facility in Florida on December 27th at 18:01 CST (28th 00:02 UTC ).

SMG Lead Meteorologist Dan Bellue worked his 86th mission and the 16th as Lead. Steve Sokol was the Assistant Lead and Doris Rotzoll was the Techniques Development Unit Meteorologist.

The Spaceflight Meteorology Group web site is at http://www.srh.noaa.gov/smg. NASA Space Shuttle information is available at http://www-pao.ksc.nasa.gov/kscpao/schedule/schedule.htm.

Submitted by:
Dan G. Bellue
STS 103 Lead Meteorologist