The Orbit Attitude and Maneuvering System or OAMS was a propulsion system used in orbit by the Gemini spacecraft.

Adapted from publication: On Shoulders of Titans: A History of Project Gemini (Hacker, Barton C., and James M. Grimwood. NASA SP-4203, 1977, reprinted 2002):

Besides letting a pilot steer the spacecraft, the OAMS also held the ship steady in orbit and, at the start of the mission, provided the power to push the spacecraft away from the spent second stage of the launch vehicle and to insert the craft into orbit - or, in case of trouble, to abort the mission. The complete OAMS had 16 small engines, which burned hypergolic propellants fed under pressure from one fuel (monomethylhydrazine) and one oxidizer (nitrogen tetroxide) tank. All engines were mounted in fixed positions and were run at fixed levels of thrust. Eight of the OAMS engines were rated at 111 newtons (25 lbf) thrust and fired in pairs, allowing the pilot to pitch, roll, and yaw the spacecraft and so control its attitude. The other eight engines were rated at 444 newtons (100 lbf) thrust; two were oriented to fire forward, two backward, and two to each side. This was the maneuvering part of the system. In July 1962, the rated thrust of the two forward-firing engines was reduced to 378 newtons (85 lbf).

During Gemini 8, on March 16, 1966, OAMS engine number 8 became stuck on, resulting in uncontrollable spinning of the spacecraft. The entire OAMS had to be shut down and the mission was terminated prematurely. This resulted in modifications to OAMS to permit engine isolation.