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McDonnell Douglas DC-X
The McDonnell Douglas DC-X, also known as the Delta Clipper, was an unpiloted reusable rocket demonstrator that made twelve vertical takeoff and landing flights from 1993 to 1996.
Mechanical counterpressure suit
A mechanical counterpressure suit, also known as a Space Activity Suit, is a proposed skintight elastic spacesuit protecting against vacuum without gas pressurization; none has flown.
MEDA (Mars instrument)
MEDA (Mars Environmental Dynamics Analyzer) is a suite of environmental sensors on NASA's Perseverance rover that measures Martian weather and dust in Jezero Crater since 2021.
Medium Earth orbit
Medium Earth orbit, also called Intermediate Circular Orbit, is the band from 2,000 to 36,000 kilometers up, home to GPS, Galileo, BeiDou, GLONASS, and broadband satellites.
Meisei Electric
Meisei Electric is a Japanese manufacturer of meteorological, disaster-prevention, and space equipment, founded in Tokyo in 1938 and headquartered in Isesaki, Gunma Prefecture. It supplied instruments for Japan's first satellite, Ohsumi.
Merah Putih
Merah Putih ("Red and White") is a family of geostationary communications satellites owned and operated by Indonesia's state-owned telco Telkom Indonesia, beginning with the Telkom-4 satellite launched in 2018.
Merah Putih 2
Merah Putih 2, formerly Telkomsat HTS 113BT, is an Indonesian high throughput telecommunications satellite launched on a SpaceX Falcon 9 from Cape Canaveral in February 2024.
Mercury (spacecraft)
The Mercury spacecraft was a one-person capsule built by McDonnell Aircraft for NASA's Project Mercury, which flew two suborbital and four orbital crewed missions between 1961 and 1963.
Mercury-Atlas 6
Mercury-Atlas 6, the MA-6 mission, was the first United States crewed orbital spaceflight, launched February 20, 1962, carrying John Glenn around Earth three times in Friendship 7.
Mercury-Atlas 8
Mercury-Atlas 8, also called Sigma 7, was the third crewed orbital Mercury flight; Wally Schirra completed six orbits on October 3, 1962, then the longest American spaceflight.
Mercury-Atlas 9
Mercury-Atlas 9, also known as Mercury 9 and flown as Faith 7, was the final crewed mission of Project Mercury, with Gordon Cooper completing 22.5 orbits in May 1963.
Mercury-Redstone 1
Mercury-Redstone 1 was the first attempt to launch a Mercury spacecraft on a Redstone rocket, an unmanned November 21, 1960 attempt at Cape Canaveral whose engine shut down just after ignition.
Mercury-Redstone 3
Mercury-Redstone 3, also known as Freedom 7, was the first United States human spaceflight, launched May 5, 1961, carrying Alan Shepard on a 15-minute suborbital flight.
Mercury-Redstone 4
Mercury-Redstone 4, known as Liberty Bell 7, was the second and final crewed Project Mercury suborbital flight, launched July 21, 1961, carrying Gus Grissom; the capsule sank after splashdown but was recovered in 1999.
MESSENGER
MESSENGER was a NASA spacecraft that became the first to orbit Mercury, operating from March 2011 until it was deliberately crashed into the planet in April 2015.
Meteor-M
Meteor-M (Метеор-М) is a series of Russian polar-orbiting weather and remote-sensing satellites built by VNIIEM for Roscosmos and Roshydromet, launched since 2009 from Baikonur and Vostochny to provide cloud imaging, sea-ice monitoring, and search and rescue.
Meteosat
Meteosat is a series of European geostationary meteorological satellites, first launched in 1977, that provides continuous full-disc imagery of Europe, Africa, and surrounding oceans for weather forecasting and climate monitoring.
MethaneSAT
MethaneSAT is an Earth-observing satellite spectrometer launched in March 2024 by the Environmental Defense Fund to quantify methane emissions from oil and gas basins worldwide.
Michael Collins (astronaut)
Michael Collins was an American astronaut who served as Apollo 11 command module pilot, orbiting the Moon in 1969 while crewmates Armstrong and Aldrin made the first crewed lunar landing.
Michael Fincke
Edward Michael "Mike" Fincke is a retired American NASA astronaut and Air Force colonel who flew four missions, spent 549 days in space, and completed nine spacewalks before retiring in 2026.
Michael J. Massimino
Michael J. Massimino (born 1962) is an American engineer and former NASA astronaut who flew on the final two Hubble servicing missions, performing four spacewalks, and now teaches at Columbia University.
Michael P. Anderson
Michael P. Anderson, also known as Michael Phillip Anderson, was an American astronaut who was payload commander of the ill-fated Space Shuttle Columbia mission in 2003.
Micro-Nova (lunar hopper)
Micro-Nova, also written µNova, is a rocket-propelled lunar hopper built by Intuitive Machines to reach permanently shadowed craters and steep slopes a wheeled rover cannot.
MicrOmega
MicrOmega is a visible and near-infrared hyperspectral microscope, developed at the Institut d'Astrophysique Spatiale in France, that analyzes powdered planetary samples aboard the ExoMars Rosalind Franklin rover.
Microscopic Imager
The Microscopic Imager was a fixed-focus camera on the robotic arms of NASA's Mars rovers Spirit and Opportunity, taking extreme close-up views of rocks and soils.
Mid-Atlantic Regional Spaceport, Wallops Island, Virginia
The Mid-Atlantic Regional Spaceport (MARS) is a commercial spaceport on Wallops Island, Virginia, operated by the Virginia Spaceport Authority, which supplies the International Space Station and launches Antares and Electron rockets.
Mid-Infrared Instrument
The Mid-Infrared Instrument (MIRI) is a camera and spectrograph on the James Webb Space Telescope that observes mid-infrared light at wavelengths from 4.9 to 28.8 micrometers.
Mikoyan-Gurevich MiG-105 (МиГ-105)
The Mikoyan-Gurevich MiG-105 (МиГ-105), also called the 105 Vehicle, was a Soviet piloted test analog of the Spiral orbital spaceplane, air-launched from a Tu-95 in 1977 and 1978.
Milani
Milani is a 6U CubeSat built by Tyvak International for ESA's Hera planetary defense mission, scheduled to map the asteroids Dimorphos and Didymos after deployment in January 2027.
Military satellite
A military satellite is an uncrewed spacecraft operated by a defense ministry or armed forces to support communications, navigation, reconnaissance, missile warning, and signals intelligence, often with dual civilian uses.