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Delta 7925
The Delta 7925 was a three-stage American expendable launch vehicle of the Delta II family, flown from 1990 to 2009 and used to launch GPS satellites and NASA Mars missions.
Delta 7925-9.5
The Delta 7925-9.5 was a three-stage American Delta II launch vehicle with nine strap-on boosters, the workhorse for GPS satellites and NASA missions like Deep Impact.
Delta II
The Delta II was an American expendable launch vehicle that flew 155 missions from 1989 to 2018, launching GPS satellites and NASA missions including the Mars rovers.
Delta IV
Delta IV, also known as Delta 4, was an American expendable rocket family developed by Boeing, whose Heavy variant was the United States' primary heavy-lift rocket.
Delta IV Heavy
Delta IV Heavy, also known as Delta 4 Heavy, was a heavy-lift rocket flown by United Launch Alliance from 2004 to 2024, largely for national security missions.
Delta-K
Delta-K is the restartable hypergolic second stage of the Delta II rocket, powered by an Aerojet AJ10-118K engine, flown from 1989 to the final Delta II flight.
Delta-v (Δv)
Delta-v (Δv, delta-vee) is the change in velocity a spacecraft's propulsion system can produce, measured in km/s and serving as the basic currency of mission design, since required propellant grows exponentially with it.
Delta-v budget
A delta-v budget is the sum of all velocity changes a spacecraft must generate over its mission, from launch correction through orbit maintenance to disposal, plus the propellant those maneuvers require.
Demonstration Rocket for Agile Cislunar Operations
The Demonstration Rocket for Agile Cislunar Operations (DRACO) was a United States program led by DARPA with NASA to demonstrate a nuclear thermal rocket engine in orbit, planned for 2027.
Dennis Tito
Dennis Tito is an American engineer and investment manager who became the first paying space tourist, visiting the International Space Station aboard a Russian Soyuz in 2001.
Deorbit of Mir
The deorbit of Mir was the deliberate, controlled reentry of Russia's Mir space station into the South Pacific Ocean on March 23, 2001, after 15 years in orbit.
Deorbit sail
A deorbit sail, also called a drag sail, is a deployable membrane that raises a satellite's atmospheric drag so it reenters and burns up sooner, without propellant.
Department of Defense Space Shuttle missions
The Department of Defense Space Shuttle missions were 11 classified military and intelligence flights of NASA's Shuttle between 1982 and 1992, from STS-4 to the final dedicated mission, STS-53.
Deployable antenna reflector
A deployable antenna reflector is a large satellite antenna folded for launch and unfolded in orbit, most commonly a lightweight mesh reflector used on communications and radar spacecraft.
Derelict satellite
A derelict satellite is an artificial satellite in Earth orbit that no longer performs its mission and is not being operated, whether failed or retired to a graveyard orbit.
Derelict spacecraft
A derelict spacecraft is an inert, unsteerable object in orbit, unable to reach a graveyard orbit. The defunct Cosmos 2251 destroyed Iridium 33 in the 2009 collision.
DESTINY+
DESTINY+ (デスティニー・プラス) is a JAXA deep-space mission launching in 2028 that will fly by asteroid Apophis and then asteroid Phaethon, the Geminid meteor shower's parent, in 2030.
DFH-3
DFH-3 (Dong Fang Hong 3, 东方红三号) is a Chinese three-axis stabilized geostationary communications satellite bus developed in the 1990s by the China Academy of Space Technology, whose platform later baseed 41 satellites.
DFH-3B
DFH-3B is a Chinese geostationary satellite bus from the China Academy of Space Technology, the platform for BeiDou-3 GEO and IGSO satellites and LaoSat 1.
DFH-4
DFH-4 (Dong Fang Hong 4) is a large geostationary communications satellite bus developed by the China Academy of Space Technology, first launched in 2006 and sold to international customers.
Diamant
Diamant, French for diamond, was France's first satellite launch vehicle, flown from 1965 to 1975; its debut launch carried the Astérix satellite and made France the third space power.
Dick Scobee
Dick Scobee, formally Francis Richard Scobee, was an American astronaut and Air Force test pilot who commanded the ill-fated final flight of the Space Shuttle Challenger in 1986.
Differential GPS
Differential GPS, also known as DGNSS, is an augmentation technique that improves GPS accuracy to 3 to 5 meters by broadcasting corrections from a surveyed reference station.
DigitalGlobe
DigitalGlobe, originally EarthWatch Incorporated, was an American commercial provider of high-resolution Earth-imagery products, operating its own imaging satellites and acquired by Maxar Technologies in 2017.
Dilution of precision (navigation)
Dilution of precision (DOP), also called geometric dilution of precision, is a unitless satellite navigation measure of how satellite geometry amplifies ranging errors in position.
Direct-broadcast satellite television in Latin America and the Caribbean
Direct-broadcast satellite television in Latin America and the Caribbean delivers pay TV to home dishes, growing from 2 million households in 1998 to about 31 million by 2014.
Direct-to-device satellite connectivity
Direct-to-device (D2D) satellite connectivity, also called direct-to-cell, is a service architecture enabling standard smartphones to reach areas terrestrial networks do not cover.
Direct-to-home television in India
Direct-to-home television in India, also known as DTH in India, delivers satellite TV directly to a subscriber's dish and set-top box, first launched as Dish TV in 2003.
DirecTV
DirecTV is an American direct-broadcast satellite and streaming television service launched in 1994, once the country's top pay-TV distributor and now wholly owned by TPG.
Discoverer
Discoverer was the public cover name of a US satellite series launched from Vandenberg between 1959 and 1962, masking the classified CORONA film-return spy satellite program.