Return to Human Space Flight home page

Mission Events Summary
Terminal Count
Extends from T minus 20 minutes through SRB ignition.

First Stage
Extends from SRB ignition through SRB separation.

Second Stage
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 vehicle performance.
Designed to allow return of orbiter and crew to KSC launch site.
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 KSC.
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.

Orbit Insertion
Following MECO, one or two propulsive thrusting periods move the vehicle to the desired orbital altitude.

On Orbit
Guidance, navigation and control during orbit phase.

On-Orbit Checkout
The day before deorbit, the crew performs a checkout of systems used during entry.

Phase includes deorbit burn preparation through descent to 400,000 feet.

Phase begins at 400,000 feet and ends at touchdown.

Curator: Kim Dismukes | Responsible NASA Official: John Ira Petty | Updated: 04/07/2002
Web Accessibility and Policy Notices