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Trajectory design is needed for each Shuttle mission.
Although
the missions we currently fly are similar (all go to the International
Space Station), there are slight differences in each mission.
Payload weight,
specific orbiter, mission requirements, time of
year we launch, wind, Solid
Rocket Booster performance, and even
the individual engines used on the mission will affect the trajectory
we fly.
There are several areas of
trajectory design for which my group is
responsible. The most important of these is the design of the
pitch, yaw and engine throttling tables on launch day.
Balloons are released from Cape Canaveral Air Force Station
which provide us with wind and atmospheric information.
This data, combined with information about the orbit
which we wish to obtain, and the precise amount of propellant
which is loaded into the External
Tank (which we monitor), is used
to "fly out" a trajectory with a computer program. The output
from this program gives us a table of pitch and yaw attitudes
which the Shuttle will be commanded to fly, as well as when
and how much the main engines throttle down and then up again.
These attitude and throttle commands are then loaded onto the
Space Shuttle a couple of hours before launch.
Currently,
my specific area of responsibility is the prediction of
how much propellant will be loaded into the External Tank at launch.
On launch day we use a program which monitors telemetry from
the tank and gives a prediction of final loading, which is fed into
the computer simulation which is run about 3.5 hours prior to
launch. It is this simulation which designs the final trajectory
as mentioned above.
The larger group I work in designs all phases of
the flight, including
ascent, on-orbit, entry,
descent, approach and landing, and all
potential abort scenarios.
Currently, I am working on STS-127 which should launch in
August 2009. My first flight, STS-104,
launched in July 2001.
I have also worked on STS-110,
113, 114,
121, 116,
117,
