OAO		Orbiting Astronomical Observatory
OARE		Orbiter Acceleration Research Experiment
OART		Office of Advanced Research and Technology
OAS		Orbit Adjust Stage
OAS		Onizuka Air Station
OBV		Orbital Boost Vehicle
OC		Optical Communications
OCC		Operartions Control Center
OCI		Ocean Color Imager
OCO		Orbiting Carbon Observatory
OD		Orbit Determination
OFO		Orbiting Frog Otolith
OGO		Orbiting Geophysical Observatory
OHSFP		Office of Human Space Flight Programs
OIC		Orbital Imaging Corporation
OKB		Opytno Konstruktorskoye Byuro
OMS		Obital Maneuvring System
OMS		Operational Meteorological Satellite
ONR		Office of Naval Research
OOCO		On-Orbit Check-Out
OPEP		Orbital Plane Experimental Package
OPLE		Omega Position Location Equipment
ORBIS		Orbiting Radio Beacon Ionospheric Satellite
ORBITA		Organización de Recursos Básicos para la Investigación Tecnológica Aerospacial
OREX		Orbital Reentry EXperiment
ORIS		Orbiting Radio Ionospheric Satellite
OSC		Orbital Sciences Corporation
OSCAR		Orbiting Satellite Carrying Amateur Radio
OSF		Office of Space Flight
OSO		Orbiting Solar Observatory
OST		Orbital Solar Telescope
OSTA		Office of Space and Terrestrial Aplication
OTM		Orbital Trim Maneuver
OTRAG		Orbital Transport und Raketen-AktienGesellschaft
OTS		Orbital Test Satellite
OV		Orbiting Vehicle