Overview
If a malfunction forces an ascent abort, several options are available.

Return-to-Launch-Site
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.