The Spaceflight Meteorology Group

Postflight Mission Summary for STS-88

January 6, 1999

International Space Station Construction Begins

The Space Shuttle Endeavour landed at Florida’s Kennedy Space Center (KSC) Shuttle Landing Facility at 10:53 PM EST (0353 UTC) on Monday, December 14, 1998 after a very successful 11 day mission. Endeavour launched from KSC’s Pad 39A on Friday, December 4, at 3:35 AM EST (0835 UTC) after a one day delay. Mission objectives included a rendezvous with the Russian built Zarya segment which had been launched in November, moving the US built node 1 (Unity) upon Endeavour’s docking mechanism and docking the Shuttle/Unity to Zarya, and completing three space walks to make additional connections on the new International Space Station. All objectives were accomplished.

The planned launch day had been Thursday, December 3rd but an electrical problem late in the launch count delayed the launch one day. Prior to the electrical problem, the weather had been a key factor in the launch decision. A high pressure system covered the southeast US and southwestern Atlantic. Showers developed over the water and moved towards the Florida coast in the southeast flow. Moderate rain showers moved into the launch (and emergency return landing area) an hour prior to the scheduled launch. There are stand-off distances for rain showers that must be met for the launch site and also for the landing site at KSC, in the event of a launch abort. The showers cleared the launch area minutes before the scheduled launch, but were predicted to be near the stand-off distance limit for landing at return-to-launch site (RTLS) abort landing time. At the final decision point, the observed and forecast RTLS landing weather was No-Go. However, this became a moot point when the electrical problem occurred. For the next day’s launch attempt, the KSC weather was better, with scattered low clouds and no showers in the KSC area. One of the three TAL sites had acceptable weather. Only one “Go” TAL site is required for launch. Endeavor launched on time at 0835 UTC December 4, at the opening of the 5 minute launch window.

Weather also played an important role on the December 14 landing day. An upper level trough moving into the southeast US caused a surface low pressure system to develop off the Florida coast, east of KSC. A shield of low clouds developed around the low and spread west over eastern Florida about 15 hours prior to landing. The northeast movement of the low and daytime heating eroded the clouds over the land during the day. By sunset, the edge of the cloud shield was along the coast at KSC. The SMG landing forecast called for scattered low clouds at landing time. The forecast also included a chance of ceilings for the possibility that the cloud deck would develop westward under the inversion as temperatures dropped. As the landing count continued, the weather reconnaissance aircraft and infrared satellite imagery showed very slow eastward movement of the cloud shield. At about 1 hour before the de-orbit burn, or 2 hours before landing, the clouds continued to show a slow eastward progression and the chance of low cloud ceilings at KSC was dropped from the SMG forecast, making the landing forecast a “Go.” Endeavour landed under mostly clear skies.

Mission Lead Forecaster for STS-88 was Karl A. Silverman, working his 31st mission, 5th as Lead. Richard Lafosse was Assistant Lead and Doris Rotzoll worked as the Lead Techniques Development Unit Meteorologist.

Submitted by:

Karl A. Silverman

Mission Trivia:
10th night landing.
17 KSC landings in a row.
6 on-time landings in a row.
25 KSC landings out of the past 30.
KSC landing total is now 46 which exceeds EDW total of 45. (WSSH = 1)
Only the 2nd KSC landing with Clear Skies reported. The other was STS-50.
Last KEDW landing was 3/31/96 (STS-76).