Did you ever wonder what those strange conglomerations of letters meant? Here's your chance to find out what those NASA acronyms stand for. About Space and Astronomy presents the Guide to NASA Acronyms. From Operations and Flight Support to Orbiter Maintenance Man-Hours and Operations and Maintenance Plan to Oxidizer, you'll find them here. This page lists acronyms starting with O. For others, click on the appropriate letter above or below.

[O]

O: Engineering Order
O&C: Operation(s) and Checkout (Building-was MSOB)
O&C: Operation and Checkout
O&C: Operations and control
O&C: Operations and checkout
O&FS: Operations and Flight Support
O&M: Operation and Maintenance
O&P: operations and Procedures
O&R: Overhaul and Repair
O-NAV: Onboard Navigation
O/B: Operational Base
O/B: Onboard
O/C: Operations Critical
O/D: On Dock
O/D: Outside Diameter
O/ET: Orbiter/External Tank
O/F: Oxidizet--to-Fuel Ratio
O/L: Overload
O/L-RC: Overload-Reverse Current
O/R: Oxygen Relief
O/R: Outside Radius
O/V: Overvoltage
O/V-U/V: over Voltage/Under Voltage
O2: Oxygen
OA: Overall
OA: Output Axis
OA: Orbital Assembly
OA: Operational Instrumentation MDM-Aft
OA: Office of Applications (now OSTA)
OA: Operational Aft (DSC or MOM)
OAA: Orbiter Access Arm
OAA: Orbiter Alternate Airfield
OAA: Orbiter access arm
OAC: Quality Assurance Chart
OAFD: Orbiter Air Flight Deck
OAFTO: Orbiter Atmospheric Flight Test Office
OAL: Overall Level
OALC: Ogden Air Logistics Center
OAMS: Orbital Attitude and Maneuvering System
OAS: Office Automation System
OAS: Orbiter Aeroflight Simulator
OAS: Orbiter Atmospheric Simulator
OAS: Orbiter Avionics System
OASCB: Orbiter Avionics Software Control Board
OASIS: Oceanic and Atmospheric Scientific Information System
OASPL: Overall Sound Pressure Level
OAST: Office of Aeronautics and Space Technology
OAT: Overall Test
OAT: Operational Acceptance Test
OB: Onboard
OB: Operational Base
OB: Outboard
OBC: Onboard Computer
OBCO: Onboard Checkout (Instrumentation)
OBCS: Onboard Checkout Subsystem
OBS: "Observe, Observer"
OBS: Operational Biomedical System
OBS: Operational Biomed Sensors
OBS: Operational Bioinstrumentation System
OBS: Operational bioinstrumentation system
OBV: Oxidizer Bleed Valve
OCALC: Oklahoma City Air Logistics Center
OCD: Operational Capability Development
OCDR: Orbiter Critical Design Review
OCDU: Optics Coupling Data Unit (G&N)
OCE: Ocean Color Experiment
OCF: Orbiter Computational Facilities
OCF: Onboard Computational Facility
OCH: Orbiter Common Hardware
OCN: Order Control Number
OCP: Output Control Pulse
OCR: Optical Character Recognition
OCRM: Orbiter Crash and Rescue Manuals
OCT: "Octal, Octave"
OD: Operations Directive
OD: Operational Downlink/Downlist
OD: Outside Diameter
OD: Oxygen Drain
ODB: Operational Data Book
ODC: Other Direct Costs
ODCDR: Orbiter Delta CDR
ODDS: Operational Data Delivery Services
ODES: Optical Discrimination Evaluation Study
ODF: Orbit Determination Facility
ODIN: Orbital Design Integration (System)
ODP: Operational Display Procedure
ODR: OutPut Data Redundancy
ODRAN: Operational Drawing Revision Advance Notice
ODU: Output Display Unit
OEAS: Orbital Emergency Arresting System
OECO: Outboard Engine CLjtoff
OEM: Original Equipment Manufacturer
OES: Orbiter Emergency Site
OESS: Orbiter/ET Separation Subsystem
OEX: Orbiter Experiments
OEX: Orbiter experiments
OF: Operational FWD DSC or MDM
OF: Operational Instrumentation MDM-FWD
OF: Orbital Flight
OF: Outside Face
OF: Oxidizer-to-Fuel Ratio
OF: Oxygen Fill
OFCC: Office of Federal Contract Compliance
OFDS: Oxygen Fluid Distribution System
OFDS: Orbiter Flight Dynamics Simulator
OFI: Operational Flight Instrumentation
OFI: Operational flight instrumentation
OFK: OPtical Flight Kit
OFK: Officiaf Flight Kit
OFM: Original Equipment Manufacturer
OFP: Operational Flight Profile
OFP: Operational Flight Program
OFP: Orbiter Flight Program
OFS: Orbiter Functional Simulator
OFS: Orbital (Orbiter) Flight System
OFT: Orbital Flight Test
OFTDS: Orbital Flight Test Data System
OFTM: On-Orbit Flight Technique Meeting
OFTR: Orbital Flight Test Requirement
OG: Zero Gravity
OG: Outer Gimbal (Roll)
OG: Oxygen Gage
OGA: Outer Gimbal Angle
OGA: Outer Gimbal Axis
OGE: Operating Ground Equipment
OGMT: Orbiter Greenwich Mean Time
OGS: Outer Glideslope
OGS: Oxygen Generation System
OGS: Quantity Gaging System
OGV: Oxygen Gage Valve
OH: Overhaul
OH: Overhead
OHA: Operational Hazard Analysis
OHA: Orbital Height Adjustment Maneuver
OHC: Onboard Hard Copier
OHC: Optics Hand Controller
OHF: Occupational Health Facility
OHGVT: Orbiter Horizontal Ground Vibration Test
OHMM: Ohmmeter
OI: Operational instrumentation
OIA: Orbiter Interface Adapter
OIA: Office of International Affairs
OIB: Orbiter Interface Box
OIR: Operations Integration Review
OISR: Open Item Status Report
OISSP: Office of Interim Space Station Program
OIT: Orbiter Integrated Test
OJT: On-the-Job Training
OL: Operational Left DSC or MDM
OL: Open Loop
OLDB: On-Line Data Bank
OLDR: Quick Look Data Reference
OLF: Orbiter Landing Facility (now SLF)
OLIF: Orbiter Landing Instrumentation Facilities
OLOW: Orbiter Lift-off Weight
OLSA: Orbiter/LPS Signal Adapter
OLSP: Orbiter Logistics Support Plan
OM: Outer Marker (ILS)
OM: Optical Master
OM: Operational Mid DSC or MDM
OM: Orbiter Main Engine
OM: Orbital Maneuvering Engine
OM RS: Operations and Maintenance Requirements Specification
OMA: Orbiter Maintenance Area
OMA: Operations Maintenance Area
OMB: Office of Management and Budget
OMBUU: Orbiter Midbody Umbilical Unit
OMCF: Operations and Maintenance Control File
OMCF: Orbiter Maintenance and Checkout Facility
OMD: Operations and Maintenance Documentation
OMD: Orbiter Mating Device
OMDR: Operations and Maintenance Data Record
OMDRI: Operations and Maintainability Data Record
OME: Orbital Main Engine
OMET: Orbiter Mission Elapsed Time
OMEWG: Orbiter Maintenance Engineering Working Group
OML: Outer Mold Line
OML: Orbiter Mold Line
OML: Outside Mold Line
OMMH: Orbiter Maintenance Man-Hours
OMNI: Omni-Range
OMNI: Omnidirectional
OMP: Operations and Maintenance Plan
OMPR: Operational Maintainability Problem Reporting
OMPT: Observed Mass Point Trajectory
OMR: Orbiter Management Review
OMR: Operations Management Room
OMR: Operations and Maintenance Requirements
OMRB: Operating Material Review Board
OMRC: Operational Maintenance Requirements Catalog
OMRF: Orbiter Modification and Refurbishment Facility
OMRP: Operations and Maintenance Requirements Plan
OMRSD: Document
OMRSD: Operational Maintenance Requirements and Specification
OMRSD: O&M Requirements and Specifications Documentation
OMRSD: Operational Maintainability Reporting Systems Document
OMS: Orbital maneuvering system
OMSF: Office of Manned Space Flight (now OSTS)
OMSP: Operational Maintenance Support Plan
OMiS: Operational Management Information System
OMiSS: Operation and Maintenance Instruction Summary Sheet(s)
ONBD: Onboard
ONBT: Orbiter Neutral Buoyancy Trainer
OND: Operator Need Date
ONR: Office of Naval Research
OOD: Orbiter On-Dock
OODP: Out-of-Detent Pitch
OODR: Out-of-Detent Roll
OOP: Out of Position
OOSDP: On-Orbit Station Distribution Panel
OOT: Out of Tolerance
OP: Operate
OP: Oxygen Purge
OP: Operation
OP: Open
OPA: Operations Planning Analysis
OPB: Oxidizer Preburner
OPBOV: Oxidizer Preburner Oxidizer Valve
OPDAR: OPtical Detection and Ranging
OPE: Other Project Element
OPER: "Operations, Operate, Operator"
OPER: Operation
OPF: Orbiter Processing Facility
OPF: Orbiter Processing Facility
OPFC: Orbiter Preflight Checklist
OPGUID: OPtimum Guidance (Technique)
OPI: Orbiter Payload Interrogator
OPIDF: Operational Planning Identification File
OPIS: Orbiter Prime Item Specification
OPL: Open Problem List
OPL: Operational
OPLF: Orbiter Processing and Landing Facility
OPNS: Operational Phase
OPO: Orbiter Project(s) Office
OPOV: Oxidizer Preburner Oxidizer Valve
OPOV: Oxidizer preburner oxidizer valve
OPP: OPPosite
OPP: Opportunity
OPPAR: Orbiter Project(s) Parts Authorization Request
OPPL: Orbiter Project Parts List
OPR: Oxygen Pressure Regulator
OPR: Orbiter/Payload Recorder
OPR: Operator
OPR: Operations Planning Review
OPR: Office of Primary Responsibility
OPRV: Oxygen Pressure Relief Valve
OPS: Orbiter Project schedules
OPS: Oxygen Purge System
OPS: Operations Sequence
OPS: Operations
OPS: Operational sequence
OPSB: Orbiter Processing SuPport Building
OPSR: Operations Supervisor (GSTDN Site)
OPSS: Orbital Propellant Storage Subsystem
OPT: optimum
OPT: optics
OPT: Option
OPT: OPerational Pressure Transducer
OPTB: Operational Program Time Base
OPTB: Opposite
OR: Operations Room
OR: Operations Review
OR: Operations Requirement
OR: Outer Roll
OR: Oxygen Relief
OR: OPerational Right
ORB: "Orbit, Orbital, Orbiter"
ORB: Order
ORB 1 -g: Orbiter one-g (trainer)
ORCHIS: Oak Ridge Computerized Hierarchical Information
ORCHIS: System
ORD: Operational Requirements Document
ORD: Operational Readiness Date
ORD: Operational Ready Data
ORD: Ordnance
ORD: Orbital Requirements Document
ORDC: Orbiter Data Reduction Center
ORE: On-Orbit Repair Experiment
ORF: Orifice
ORG: Organization
ORI: Operational Readiness Inspection
ORIDE: Override
ORIEN: Orientation
ORIG: Origin
ORLA: OPtimum Repair Level Analysis
ORP: OFS Retransmission Processor
ORR: Operational Readiness Review
ORR: Operations Requirements Review
ORS: "Orroval Valley, Australia (STDN)"
ORS: Orbital Refueling System
ORSDI: Oak Ridge Selective Dissemination of Information
ORT: Orbit Readiness Test
ORT: Operational Readiness Test
ORTHOG: Orthogonal
OSA: Operational Support Area
OSDH: Orbiter System Definition Handbook
OSE: Orbiter Support Equipment
OSE: Operating SupPort Equipment
OSF: Office of Space Flight (now OSTS)
OSF: Ordnance Storage Facility
OSHA: Occupational Safety and Health Act (Activity)
OSHA: Occupational Safety and Health Administration
OSLM: Operations ShOP/Lab Manager
OSMP: Operational SuPport Maintenance Plan
OSOP: Orbiter Systems Operating Procedures
OSP: Operations Support Plan
OSR: Operations Support Room
OSSA: Office of Space Science and Applications
OSSRH: Orbiter Subsystem(s) Requirements Handbook
OST: Orbiter SuPport Trolley
OST: Operations Support Team (GSFC)
OSTA: Office of Space and Terrestrial Application(s)
OSTDS: Office of Space Tracking and Data Systems
OSTO: Office of Space Transportation Operations
OSTP: Orbiting System Test Plan
OSTS: Office of Space Transportation Systems
OT: Operational instrumentation MDM-Tank
OT: Out Temperature
OT: Operating Time
OT: Overti me
OT: Operational Trajectory
OT: Operational Test
OT: Optical Tracker
OT&E: Operational Test and Evaluation
OTA: Optical Telescope Assembly
OTB: Orbiting Tanker Base
OTBD: Outboard
OTC: Orbiter Test Conductor
OTD: Operational Technical Documentation
OTD: Orbiter Test Director
OTDA: Office of Tracking and Data Acquisition (now OSTDS)
OTEMP: Overtemperature
OTH: Over-the-Horizon (.Radar)
OTK: Oxidizer Tank
OTL: Ordnance Test Laboratory
OTLC: Orbiter Timeline Constraints
OTO: One-Time-Only
OTOS: Orbit-to-Orbit Stage
OTP: Operations Turnaround Plan
OTP: Operations Test Plan
OTP: OPerational Test Procedure
OTR: Outer
OTR: Operating Time Record
OTS: Orbiter Test Conductor
OTS: Off-the-Shelf
OTT: Optional Team Targeting
OTV: Operational Television
OTV: Orbiter Transfer Vehicle
OTV: Orbital transfer vehicle
OTY: Quantity
OUP: OFS UPlink Processor
OUT: Orbiter Utilities Tray
OUT: Output
OUT: Outlet
OUTBD: Outboard
OV: Orbiter vehicle
OVBD: Overboard
OVF: Overfill
OVFL: Overf low
OVHD: Overhead
OVHT: Overheat
OVLD: Overload
OVRD: Override
OWD: One-Way Doppler
OWDE: One-Way Doppler Extraction
OWF: OPtimum Working Frequency
OXD: "Oxide, Oxidizer"
OXDZR: Oxidizer
OXID: Oxidizer
OXY: Oxygen
Oil: Operations Integration Instruction

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