| m | meter |
| M-AERI | Marine-Atmosphere Emitted Radiance Interferometer |
| m-g | milli-g (Earth's gravitational acceleration) |
| M&A | Measurement and Analysis |
| M&C | Monitor and Control |
| M&P | Materials and Processes |
| M&S | Modeling and Simulation |
| MA | Mission Assurance |
| ma | milli-ampere(s) |
| MA | Momentum Adjust |
| MAC | Mandatory Access Control |
| MAD | Margin Allocation Document |
| MAG | Magnetometer |
| MAGED | Magnetospheric Electron Detector |
| MAGIC | Mesoscale Atmospheric Global Irradiance Code |
| MAGPD | Magnetospheric Proton Detector |
| MAIAC | Multi-Angle Implementation of Atmospheric Correction |
| MAID | Master Action Item Database |
| Master Action Item List | |
| MAIP | Mission Assurance Implementation Plan |
| MAM | Mission Assurance Manager |
| MAP | Mission Assurance Plan |
| MAR | Mission Assurance Requirements |
| MaRR | Manufacturing Readiness Review |
| MARS | Monitoring, Analysis and Response System |
| MARS | Multimode Aeronautical Radio System |
| MASC | Mission Assurance Support Contract |
| MAST | Monitoring and Analysis Software Tools |
| MAT | Mission Allowable Temperature |
| MAT | Mission Assurance Terminal |
| MaxTTRS | Maximum Time to Restore Service |
| mb | millibar |
| MB | megabyte (10E6 bytes) |
| Mbps | megabits per second (10E6 bits) |
| MCA | Magnetically Controlled Area |
| MCC | Master Control Console |
| MCC | Maximum cross-correlation |
| MCDM | Multi-Criteria Decision Making |
| MCID | Master Channel ID |
| McIDAS | Man-computer Interactive Data Access System |
| MCM | Multi-Chip Module |
| MCOM | Mission Communications Operations and Maintence |
| MCP | Management Control Plan |
| MCP | Master Control Procedure |
| MCP | Micro Channel Plate |
| MCR | Mission Confirmation Review |
| MCRR | Mission Confirmation Readiness Review |
| MD | Momentum Desaturation |
| MD-5 | Message Digest - 5 |
| MDAA | Mission Directorate Associate Administrator |
| MDC | Mapped Diagnostic Context |
| MDD | Metadata Document |
| MDL | Multiuse Data Link |
| MDR | Mission Definition Review |
| MDR | Mission Design Review |
| ME | Materials Engineer |
| MEB | Materials Engineering Branch |
| MECO | Main Engine Cut-Off |
| MEDA | Macintyre Electronic Design Associates |
| MEF | Mission Essential Functions |
| MEFL | Maximum Expected Flight Level |
| MEMSCAG | Multiple End Member Snow Covered Area and Grain |
| MEO | Medium Earth Orbit |
| MEOP | Maximum Expected Operating Pressure |
| MEP | Message Exchange Platform |
| MERIS | Medium Resolution Imaging Spectrometer |
| MES | Main Engine Start |
| MESO | Mesoscale |
| MET | Mission Elapsed Time |
| METE | Mission End-to-End Testing |
| MetOp | Meteorological Operational |
| METOP | European Meteorological Operational SC |
| MFB | Multi-Function Bus |
| MFR | Memorandum For the Record |
| MGA | Maturity Growth Allowance |
| MGH | Massachusetts General Hospital NSCL |
| MGSE | Mechanical Ground Support Equipment |
| MHz | MegaHertz |
| MI | Microwave imagery |
| MIB | Mishap Investigation Board |
| MIB | Multiple Interface Board |
| MIC | Meets Intent Certification |
| MICD | Mechanical Interface Control Document |
| MIKR | Mission Integration Kickoff Review |
| MIL | Military |
| MIL-STD | Military standard |
| MIP | Mandatory Inspection Point |
| MIPS | Millions of Instruction Per Second |
| MIS | Microwave Imager/Sounder (NPOESS) |
| MISR | Multi-angle Imaging Spectro-Radiometer (EOS) |
| MISTIC | Meteorological Imager Scene & Timeline Center |
| MITEQ | Microwave Information Transmission Equipment |
| MIT-LL | Massachusetts Institute of Technology - Lincoln Laboratory |
| MLI | Multilayered Insulation |
| MLS | Mission Life/Lifetime Storage |
| MLS | Multi-Level Security |
| MLT | Magnetic Local Time |
| mm | millimeter |
| MM | Mission Management (Ground Segment Element) |
| MMD | Mean Mission Duration |
| MMFR | Mission Management Flight Ready |
| MMI | Man-Machine Interface |
| MMOD | Micro-Meteoroid Orbital Debris |
| MMP | Mission Management Prototype |
| MMPDS | Metallic Materials Properties Development and Standardization |
| MMR | Monthly Metrics Review |
| MOA | Memorandum of Agreement |
| MOAP | Mission Operations Assurance Plan |
| MOC | Mission Operations Center |
| MOCART | Monte Carlo Atmospheric Model |
| MOCI | Mission Operations Configuration Item |
| MOD06 | Moderate Resolution Imaging Spectroradiometer (MODIS) Cloud Product algorithm |
| MOD35 | Moderate Resolution Imaging Spectroradiometer (MODIS) Cloud Mask algorithm |
| MODB | Mission Operations Database |
| MODEM | Mission Operations Daily Exchange Meeting |
| MODIS | Moderate Resolution Imaging Spectroradiometer |
| MODTRAN | MODerate resolution atmospheric TRANsmission |
| MOE | Measure Of Effectiveness |
| MOG | Moderate or greater |
| MOI | Moment of Inertia |
| MOLP | Mission Operational Life Phase |
| MOM | Mission Operations Manager |
| MOMS | Mission Operations and Mission Services |
| MON | Mixed Oxides of Nitrogen |
| MOP | Measure of Performance |
| MOP | Mission Operations Plan |
| MOPS | Millions of Operations Per Second |
| MOR | Mission Operations Review |
| MOSFET | Metal Oxide-Silicon Field Effect Transistor |
| MOST | Mission Operations Support Team |
| MOT | Missions Operations Test |
| MOU | Memorandum of Understanding |
| MOWG | Mission Operations Working Group |
| MP | Media Protection |
| MPC | Marine Prediction Center |
| MPC | Merged Processing Center |
| MPCB | Material and Processes Control Board |
| MPCP | Mishap Preparedness and Contingency Action Plan |
| MPD | Mission Phase Discriminator |
| MPLNET | Micro –Pulse Lidar Network (NASA) |
| MPLS | Multi-Protocol Label Switching |
| MPR | Monthly Program Review |
| MPS | Magnetospheric Particle Sensor |
| MPS | Master Production Schedule |
| MPS | Mission/MM Planning and Scheduling |
| MPS-HI | Magnetospheric Particle Sensor - High Energy Range |
| MPS-LO | Magnetospheric Particle Sensor - Low Energy Range |
| MR | Management Reserve |
| MRAD | Mission Resources Analysis Document |
| MRB | Material Review Board |
| MRD | Mission Requirements Document |
| MRR | Manufacturing Readiness Review |
| MRR | Material Review Report |
| MRR | Mission Readiness Review |
| MRS&S | Multiuse Data Link Receive System and Server |
| MRT | Mission Readiness Test |
| ms | milliseconds |
| MSD | Mission Support Division |
| MSDS | Materials Safety Data Sheets |
| msec | millisecond |
| MSFC | Marshall Space Flight Center |
| MSG | Meteosat Second Generation |
| MSLP | Mean sea level pressure |
| MSOD | Mission Support Office Director |
| MSPSP | Missile Systems Pre-Launch Safety Package |
| MSR | Management Status Review |
| MSR | Monthly Status Report |
| MSR | Monthly Status Review |
| MSRD | Mission/System Requirements Document |
| MST | Maintenance Sustainment and Training |
| MST | Mission Support Team |
| MSU | Michigan State University Coupled Cyclotron Facility |
| MTA | Metering Tube Assembly |
| MTBF | Mean Time Between Failures |
| MTD | Month To Date |
| MTD | Maximum Tolerable Downtime |
| MTE | major test event |
| MTF | Modulation Transfer Function |
| MTG | Maintenance Test Group |
| MTG | MeteoSat Third Generation |
| MTL | Mission Time Line |
| MTSAT | Multifunctional Transport Satellites (Japan Meteorological Agency) |
| MTTR | Mean Time To Repair |
| MTTRS | Mean time to Restore Service |
| MUA | Materials Usage Agreement |
| MUF | Model Uncertainty Factor |
| MUMBO | Air Force Research Lab accelerator |
| MUOS | Mobile User Objective System |
| MUVR | Multilayer Ultra Violet Reflectance |
| MVC | Model/Multiple View Controller |
| MVD | Mean Vector Difference |
| MVT | Mission Validation Test |
| MVTDS | Mission Validation Test Data Sets |
| MW | Microwave |
| MWI | Manufacturing Work Instruction |
| MWIR | mid-wave infrared |
| MWSST | microwave sea surface temperature |