| Acronym | Meaning |
 | GOMOS | Global Ozone Monitoring By Occultation Of Stars |
| GOMR | Global Ozone Monitoring Radiometer |
| GOSAMR | Gelation Of Soils: Applied Microgravity Research |
| GOX | Gaseous OXygen |
| GPC | General Purpose Computer |
| GPPF | Gravitational Plant Physiology Facility |
| GPS | Global Positioning System |
| GR | General Relativity |
| GRO | Gamma Ray Observatory |
| GRS | Gamma Ray Spectrometer |
| GRS | Great Red Spot |
| GRTLS | Glide RTLS |
| GRU | Glavnoye Razvedivatel'noye Upravileniye |
| GSC | Guide Star Catalog |
| GSFC | Goddard Space Flight Center |
| GSO | GeoSynchronous Earth Orbit |
| GST | Greenwich Sidereal Time |
| GTO | Geostationary Transfer Orbit |
| GUGK | Glavnoye Upravileniye Geodesii I Kartografii |
| HAINS | High Accuracy Inertial Navigation System |
| HALOE | Halogen Occultation Experiment |
| HAO | High Altitude Observatory |
| HB | Horizontal Branch |
| HCI | Highes Communications |
| HCMM | Heat Capacity Mapping Mission |
| HD | Henry Draper Catalog Entry |
| HDE | Henry Draper Extension |
| HDM | Hot Dark Matter |
| HEAO | High Energy Astronomical Observatory |
| HERA | Hermes Robotic Arm |
| HF | High Frequency |
| HGA | High Gain Antenna |
| HH | Hitchhiker |
| HIRDLS | High Resolution Dynamics Limb Sounder |
| HIRIS | High Resolution Imaging Spectrometer |
| HIRS | High Resolution Infrared Radiation Sounder |
| HJD | Helicentric Julian Date |
| HLC | Heavy Lift Capability |
| HLV | Heavy Lift Vehicle |
| HMC | Halley Multicolor Camera |
| HOTOL | HOrizontal TakeOff And Landing |
| HPFTP | High Pressure Fuel Turbopump |
| HPOTP | High Pressure Oxidizer Turbopump |
| HR | Hertzsprung-Russell |
| HRDI | High Resolution Doppler Imager |
| HRI | High Resolution Imager |
| HRMS | High Resolution Microwave Survey |
| HRPT | High Resolution Picture Transmission |
| HRSC | High Resolution Stereo Camera |
| HRSI | High-temperature Reusable Surface Insulation |
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