- Terminal Count
- Extends from T minus 20 minutes through SRB ignition.
- Extends from SRB ignition through SRB separation.
- Begins at SRB separation and extends through main engine cutoff
and ET separation.
Ascent Abort Modes
- Abort may become necessary if there is a failure that affects
- Designed to allow return of orbiter and crew to KSC launch
- Transatlantic Landing
- Available if a main engine fails after last RTLS opportunity,
but before AOA can be accomplished.
- Abort to Orbit
- Used to boost the orbiter to a safe orbital altitude if
it is impossible to reach the planned altitude.
- Abort Once Around
- Vehicle orbits the Earth once and lands at Edwards AFB or
- Contingency Abort
- Maintains orbiter integrity for in-flight crew escape if
landing cannot be made.
Manual Thrust Vector Control
- Substitutes inputs from RHC for automatic commands from Guidance.
- Following MECO, one or two propulsive thrusting periods move
the vehicle to the desired orbital altitude.
- Guidance, navigation and control during orbit phase.
- The day before deorbit, the crew performs a checkout of systems
used during entry.
- Phase includes deorbit burn preparation through descent to 400,000
- Phase begins at 400,000 feet and ends at touchdown.