The Spaceflight Meteorology Group
Postflight Mission Summary for STS-79
October 18, 1996
...New shuttle flight duration record...
Space Shuttle Atlantis landed at the Shuttle Landing Facility (SLF), Florida at 12:13
UTC, September 26,1996, after the six person crew successfully completed their ten day
historic mission and returned Astronaut Shannon Lucid to Earth after her six month
Weather for launch day proved to be exciting. Within the last two hours of the launch
count, surface observations at both the SLF and at Zaragoza violated the weather flight
rules briefly. A low cloud deck at 9 hundred feet developed a ceiling at Zaragoza. This
deck rapidly burned off before launch. However, for a period in the launch count the prime
TAL site was observed "NO GO". Rain showers off the east coast of Florida moved
north northwestward just west of the SLF causing a "NO GO" observation within
the last hour of the count. These showers continued to move north northwestward and began
dissipating, so that no delay in the count was incurred. SMG forecasts for all sites
remained "GO" through the count, and Atlantis lifted off at the beginning of the
"5 minute" window at 08:54:48 UTC for an "on-time" launch.
The very short launch window was necessary to insert Atlantis into proper orbit to
accomplish the docking with the MIR Space Station, retrieve Astronaut Shannon Lucid, and
deploy Astronaut John Blaha for his extended flight in MIR. Secondary mission objectives
were also met successfully.
An apparent failure of an Auxiliary Power Unit (APU) caused concern to flight
controllers and mission managers. It also made the landing flight rules more restrictive,
i.e, by lessening the crosswind limit from 15 knots to 10 knots allowed for landing.
On-orbit support consisted of daily Mission Management Team (MMT) weather briefings. Five
days before the planned landing, SMG briefed detailed forecasts for landing day and for
the following two days' landing opportunities. Atlantis did have enough consumables on
board to remain on orbit until Sunday, September 29th, if necessary. However with the
apparent failed APU, mission managers decided to take the earliest opportunity to land at
the site (either Florida or California) with the most favorable weather.
Touchdown of Atlantis occurred at the Shuttle Landing Facility (SLF), KSC, Florida at
1213 UTC, September 26, after ten days in orbit. On landing day, winds at the surface and
in the low level remained east southeasterly as high pressure over the eastern U.S.
dominated weather in Florida. Normally in deep easterly flow over Florida, rainshowers and
low cloud ceilings develop over the water and advect across the Cape. This occurred to
some extent. However, a strong subsidence inversion aloft and brisk winds aloft prevented
cloud growth above about 8 000 feet. The SMG forecasters used enhanced IR satellite
imagery to identify and track low cloud elements which were confirmed by the Shuttle
Training Aircraft (STA) and the WSR- 88D at Melbourne. An anxious moment for SMG
forecasters occurred when the STA pilot announced just a few minutes before the deorbit
burn that low clouds over the water approximately 25 miles offshore were moving toward the
Cape. SMG forecasters held to a "GO" forecast, and Atlantis touched down without
incident. Weather remained favorable through post landing operations.
Lead Meteorologist for STS-79 was Dan Bellue. Tim Garner was the Assistant Lead, and
Mark Keehn worked as the Lead Techniques Development Unit (TDU) Meteorologist. This marked
the third time that these meteorologists together have worked a shuttle launch and
Submitted by: Dan G. Bellue