- ACS
- Attitude control system
- AD
- Air density satellite (Explorer)
- AE
- Atmosphere Explorer satellite
- AEROSAT
- Joint FAA-ESRO Aeronautical Satellite
- AIMP
- Anchored Interplanetary Monitoring Platform (Explorer)
- ALFMED
- Apollo light-flash moving-emulsion detection
- ALSEP
- Apollo lunar surface experiments package
- AM
- Airlock module (Skylab spacecraft component)
- AMPS
- Atmospheric, Magnetospheric Plasma-in-Space laboratory (Space Shuttle payload)
- AMU
- Astronaut maneuvering unit
- Anik
- Canadian Telesat domestic telecommunications satellite
- ANNA
- Army-Navy-NASA geodetic satellite
- APS
- Ascent propulsion system (Apollo LM component); also auxiliary propulsion system
- APT
- Automatic picture transmission
- ASTP
- Apollo-Soyuz Test Project
- ATDA
- Augmented target docking adapter
- ATM
- Apollo Telescope Mount (Skylab spacecraft component)
- AVCS
- Advanced vidicon camera system
- BBIVA,BBVC
- Black Brant IVA, Black Brant VC sounding rockets
- BE
- Beacon Explorer satellite
- BIC
- Barium-ion-cloud experiment
- BIOCORE
- Apollo 17 medical experiment (using mice)
- BIOS
- Biological Investigation of Space (suborbital flight experiment); sometimes also used as short name for Biosatellite
- CAS
- Cooperative Applications Satellite (CAS-A was Eole)
- CEPE
- Cylindrical Electrostatic Probe Experiment (orbital experiment attached to Delta second stage)
- CM
- Command module (Apollo spacecraft)
- Cos
- ESRO cosmic ray satellite
- CRISP
- Cosmic Ray Ionization Program
- CSM
- Command and service module (Apollo spacecraft, combination of CM and SM)
- CTS
- Communications Technology Satellite
- DAD
- Dual Air Density Explorer satellite
- DFBW
- Digital fly-by-wire program
- DME
- Direct Measurement Explorer satellite
- DPS
- Descent propulsion system (Apollo LM component)
- DSN
- Deep Space Network
- EASEP
- Early Apollo scientific experiments package (Apollo 11)
- ECS
- Environmental control system
- EGO
- Eccentric (orbiting) Geophysical Observatory
- EOPAP
- Earth and ocean physics applications program
- ERAP
- Earth resources aircraft program
- EREP
- Earth resources experiment package (Skylab experiment)
- EVA
- Extravehicular activity
- EXAMETNET
- Experimental InterAmerican Meteorological Rocket Network
- EXOSAT
- ESRO high-energy astronomy satellite, for x-ray astronomy
- FIRE
- Flight Investigation of the Reentry Environment (reentry heating project)
- GATV
- Gemini Agena Target Vehicle
- GEOS
- Geodetic Satellite (Explorer); also its successor, Geodynamic Experimental Ocean Satellite, and ESRO’s Geostationary Scientific Satellite
- GOES
- Geostationary Operational Environmental Satellite
- GRS
- German Research Satellite (GRS-1 was Azur; GRS-2-A, Aeros)
- GTS
- Geostationary Technology Satellite
- HAPPE
- High Altitude Particle Program Experiment
- Hawkeye
- Scientific satellite (Explorer; follow-on to Injun series)
- HCMM
- Heat Capacity Milpping Mission Explorer
- HET
- Health/education telecommunications experiment (on ATS 6)
- HL-10
- Lifting-body research vehicle
- IE
- Ionosphere Explorer
- IME
- Interplanetary meteoroid experiment
- IMP
- Interplanetary Monitoring Platform (Explorer)
- Injun
- Scientific satellite (Explorer)
- IRLS
- Interrogation, recording, and location system
- ISEE
- International Sun-Earth Explorer
- IU
- Instrument unit
- IUE
- International Ultraviolet Explorer
- IUS
- Interim upper stage for Space Shuttle (called orbit-to-orbit stage, or OOS, by Air Force; interim version of Space Tug)
- Kiwi
- Ground-test reactor for nuclear propulsion research
- LC
- Launch complex
- LDEF
- Long-Duration Exposure Facility (satellite)
- LES
- Launch escape system
- LEM
- Lunar excursion module (renamed LM)
- LLRV
- Lunar landing research vehicle
- LL TV
- Lunar landing training vehicle
- LM
- Lunar module (Apollo lunar-landing spacecraft)
- LOI
- Lunar orbit insertion
- LOR
- Lunar orbit rendezvous (Apollo lunar-landing mode)
- LRV
- Lunar roving vehicle (Rover)
- LST
- Large Space Telescope (satellite)
- Luster, Project
- Sounding Rocket experiment to capture interplanetary particles
- M2-F2
- Lifting-body research vehicle
- MAROTS
- ESR+B166O Maritime Orbital Test Satellite
- MCC
- Midcourse correction; also Mission Control Center
- MDA
- Multiple docking adapter (Skylab spacecraft component)
- MDS
- Meteoroid Detection Satellite (Explorer)
- MESA
- Modularized equipment stowage assembly (Apollo LM component)
- METEOSAT
- ESRO geostationary meteorological satellite
- MET; METS
- Mobile equipment transporter; modularized equipment transport system (for Apollo lunar landing missions)
- MSFN
- Manned Space Flight Network
- MTS
- Meteoroid Technology Satellite
- NERV
- Nuclear Emulsion Recovery Vehicle (high-altitude radiation experiment)
- NERVA
- Nuclear engine for rocket vehicle application
- NOAA
- National Oceanic and Atmospheric Administration meteorological satellite (successor to ESSA satellites)
- NOMSS
- National Operational Meteorological Satellite System
- OOS
- Orbit-to-orbit stage (see IUS)
- OSCAR
- Orbiting Satellite Carrying Amateur Radio
- OTS
- ESRO Orbital Test Satellite
- OWL
- Rice University scientific satellite (Explorer)
- OWS
- Orbital Workshop (Skylab space station)
- PAET
- Planetary Atmosphere Experiment Test (suborbital flight experiment)
- Phoebus
- Ground-test reactor for nuclear propulsion
- PLACE
- Position location and communications experiment (on ATS 6)
- PLSS
- Portable life support system
- POGO
- Polar Orbiting Geophysical Observatory
- Prometheus
- Sounding rocket for lightning research
- PS
- Payload shroud
- QUESTOL
- Quiet, experimental, short takeoff and landing aircraft
- RAE
- Radio Astronomy Explorer
- RAM
- Research and Applications Module (Spacelab forerunner)
- RAM, Project
- Radio attenuation measurement (reentry communications blackout research)
- RAM C-1, etc.
- Suborbital spacecraft in Project RAM
- RBV
- Return-beam-vidicon camera
- RCS
- Reaction control system
- RM
- Radiation/Meteoroid satellite
- RMU
- Remote maneuvering unit
- Rover, Project
- NASA-AEC research and development program of nuclear reactor propulsion for rockets
- RPRV
- Remotely piloted research vehicle
- RTG
- Radioisotope thermoelectric generator (spacecraft power system)
- S-I
- Saturn I booster first stage
- S-IB
- Saturn IB booster first stage
- S-IC
- Saturn V booster first stage
- S-II
- Saturn V second stage
- S-IV
- Saturn I second stage
- S-IVB
- Saturn IB second stage; Saturn V third stage
- SAS
- Small Astronomy Satellite (Explorer); also solar array system (Skylab Orbital Workshop component)
- Scanner, Project
- Horizon definition experiment (sounding rocket)
- Scramjet
- Supersonic combustion ramjet engine
- scs
- Stabilization and control system
- SE
- Solar Explorer satellite
- SERT
- Space Electric Rocket Test(SERT 1 was suborbital; SERT 2 was orbited)
- SEV A
- Surface extravehicular activity (lunar exploration); also standup extravehicular activity
- SHAPE
- Supersonic High Altitude Parachute Experiment
- SIM
- Scientific instrument module (Apollo SM component)
- SITE
- Satellite instructional television experiment (on ATS 6)
- SLA
- Spacecraft-lunar module adapter; also spacecraft launch vehicle adapter
- SM
- Service module (Apollo spacecraft component)
- SNAP
- Systems for nuclear auxiliary power (nuclear-electric spacecraft power supply)
- SPAN
- Solar Particle Alert Network
- SPANDAR
- Space and range radar
- SPED
- Supersonic Planetary Entry Decelerator (suborbital flight test)
- SPS
- Service propulsion system (Apollo SM component)
- SRB
- Solid (fueled) rocket booster (for Space Shuttle)
- SRM
- Solid (fueled) rocket motor
- SSME
- Space Shuttle main engine
- SSS
- Small Scientific Satellite (Explorer)
- SST
- Supersonic transport aircraft
- STA
- Shuttle training aircraft
- STADAN
- Space Tracking and Data Acquisition Network (see also STDN)
- STDN
- Spacecraft Tracking and Data Network (formerly STADAN)
- STOL
- Short takeoff and landing aircraft
- STS
- Space transportation system
- TETR
- Test and Training Satellite (MSFN training satellite; see also TTS)
- TLI
- Translunar injection (insertion into trajectory for the moon)
- TOPS
- Thermoelectric outer planets spacecraft
- Topsi
- Topside sounder satellite
- TIS
- Test and Training Satellite (MSFN training satellite; see also TETR)
- V/STOL
- Vertical or short takeoff and landing aircraft
- VTOL
- Vertical takeoff and landing aircraft
- X-15
- High-altitude, high-speed, experimental rocket research aircraft
- X-24
- Lifting-body research vehicle
- XB-70
- Experimental supersonic aircraft