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Postflight Mission Summary for STS-106
September 29, 2000
The Space Shuttle Atlantis and its seven member crew touched down in Florida at 0756
UTC on Wednesday, September 20th. This was the 23rd consecutive landing at the
Kennedy Space Center (KSC) and the 15th nighttime landing in shuttle history. While in
orbit, the STS-106 crew successfully prepared the International Space Station for the
arrival of the first permanent crew. The five astronauts and two cosmonauts also
delivered more than 6,600 pounds of supplies and installed batteries, power converters,
a toilet and a treadmill on the station. Two members of the crew also performed a space
walk to connect power, data and communications cables to the newly arrived Zvezda
Service Module and the station. This successful 12 day mission marked the completion
of the 99th shuttle mission. Extensive coverage of STS-106 can be found at:
http://www.spaceflight.nasa.gov/shuttle/archives/sts-106/index.html
Weather played a major role in the decision making process for both the launch and the
landing.
Early in the launch count, scattered rain showers covered the KSC area, violating the 'no
precipitation within 20 NM' weather flight rule. The showers were expected to diminish
but not dissipate through the count. The Return To Launch Site (RTLS) abort landing
forecast included showers within 20 NM. Weather flight rules for RTLS allows for
isolated light rain showers to exist, providing certain criteria are met. There is also an
exception in this rule which can be invoked in very specific circumstances when there
are moderate showers involved. A second concern for RTLS was thunderstorms
approaching from the northeast. Forecast movement of the anvils would bring them
over the KSC complex at abort landing time, another weather flight rule violation. The
final concern was shower development along outflow boundaries within the 20 NM
exclusion zone.
At launch minus four and a half hours, SMG briefed the astronaut crew and flight control
team, including the ascent flight director, about these issues. There were no weather
concerns at the overseas abort sites in Spain or Morocco.
The showers continued to diminish as launch time approached. The speed of the
approaching thunderstorms slowed enough to remove the threat of anvils violating
weather flight rules. Outflow boundary showers that had been developing ahead of the
approaching thunderstorms became less frequent and weaker in strength as the storms
approached. Applying the exception portion of the RTLS rain shower flight rule to the
existing and potential showers allowed for an on-time launch at 1245 UTC, the opening
of a two and a half minute launch window.
Weather concerns for landing on September 20th were also challenging. Hurricane
Gordon had dropped 2 to 3 inches of rain on the KSC complex a few days before
landing, and Tropical Depression #12 regenerated over Cuba the evening before the
landing. Also, due to a satellite eclipse, there would be no GOES East satellite imagery
during a critical portion of the landing count, from touchdown minus 4 hours (TD-4 hrs.)
to TD-1 hr (just after the de-orbit burn). Weather flight rules for landing are more
restrictive than for launch. There can be no thunderstorms, including electrified anvils,
or showers within a 30 NM radius of the runway. Radar and weather reconnaissance
aircraft reports would be especially critical.
When the Spaceflight Meteorology Group entry team relieved the planning team at
touchdown minus 9 hours (TD-9 hrs), showers were occurring along the east coast of
Florida and thunderstorms were over western and southern Florida. SMG predicted that
the thunderstorms would diminish but maintained "showers within 30 NM" in the landing
forecast.
At TD-4 hrs. (de-orbit burn minus 3 hrs.), the flight control team, including the entry flight
director, was given a thorough weather briefing. The thunderstorm activity that could
effect KSC had been decreasing, but anvils would continue to move towards KSC. The
shower activity had also been decreasing in intensity and areal coverage. The
downward trend in both thunderstorm and shower activity was expected to continue but
neither concern could yet be eliminated.
At de-orbit burn minus 1 hour, with weather recon reports confirming what the radar was
indicating, the flight director was informed that the anvils would no longer be a threat.
The only remaining concern was the shower activity, which continued to diminish.
At TD-1:30, less than a half hour before the de-orbit burn, the showers were removed
from the forecast. With no showers in the forecast, the forecast was then 'go' based on
the weather flight rules. At TD-1:20, the flight director gave the crew a 'go' for the de-
orbit burn. Five minutes later, the weather recon aircraft reported low clouds developing
near the landing runway. The astronaut pilot in the weather recon aircraft was
concerned that low clouds could block the visual landing aids. SMG briefed the flight
director and entry team that low clouds were expected and in the forecast. This
information was relayed back to the weather recon aircraft. The de-orbit burn began at
TD-1:07. A little more than an hour later the Space Shuttle Atlantis touched down on
runway 15 at KSC. At touchdown, KSC reported a few low clouds, broken high clouds,
and no precipitation within 30 NM.
For additional information about the Spaceflight Meteorology Group, shuttle weather
forecasts and landing weather requirements, please visit:
www.srh.noaa.gov/smg
Lead Forecaster for STS-106 was Karl A. Silverman working his 36th mission, 6th as
Lead. TAL Forecaster was Richard A. Lafosse and Lead Technique Development
meteorologist was Doris A. Rotzoll.
Submitted by:
Karl A. Silverman
STS-106 Lead Metorologist
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www.nws.noaa.gov 
