Delta II was an expendable launch system, originally designed and built by McDonnell Douglas. Delta II was part of the Delta rocket family and entered service in 1989. Delta II vehicles included the Delta 6000, and the two later Delta 7000 variants ("Light" and "Heavy"). The rocket flew its final mission ICESat-2 on September 15, 2018, earning the launch vehicle a streak of 100 successful missions in a row, with the last failure being GPS IIR-1 in 1997.
|Manufacturer||United Launch Alliance|
|Country of origin||United States|
|Cost per launch||US$51 million in 1987 (7920-10 mod.)|
|Height||38.2–39 m (125–128 ft)|
|Diameter||2.44 m (8 ft 0 in)|
|Mass||151,700–231,870 kg (334,440–511,190 lb)|
|Stages||2 or 3|
|Payload to LEO||2,700–6,100 kg (6,000–13,400 lb)|
|Payload to GTO||900–2,170 kg (1,980–4,780 lb)|
|Payload to HCO||1,000 kg (2,200 lb)|
|Launch sites||Cape Canaveral SLC-17|
Vandenberg AFB SLC-2W
Delta 6000: 17
Delta 7000: 132
Delta 7000H: 6
Delta 6000: 17
Delta 7000: 130
Delta 7000H: 6
|Failures||1 (Delta 7000)|
|Partial failures||1 (Delta 7000)|
|Boosters (6000 Series) – Castor 4A|
|Thrust||478 kN (107,000 lbf)|
|Specific impulse||266 s|
|Burn time||56 s|
|Boosters (7000 Series) – GEM 40|
|No. boosters||3, 4, or 9|
|Thrust||492.9 kN (110,800 lbf)|
|Specific impulse||274 s|
|Burn time||64 s|
|Boosters (7000 Heavy) – GEM 46|
|Thrust||628.3 kN (141,200 lbf)|
|Specific impulse||278 s|
|Burn time||75 s|
|First stage – Thor/Delta XLT(-C)|
|Engines||1 RS-27 (6000 series) or RS-27A (7000 series)|
|Thrust||1,054 kN (237,000 lbf)|
|Specific impulse||302 s|
|Burn time||265 s|
|Second stage – Delta K|
|Thrust||43.6 kN (9,800 lbf)|
|Specific impulse||319 s|
|Burn time||431 s|
|Fuel||N2O4 / Aerozine 50|
|Third stage – PAM-D (optional)|
|Thrust||66 kN (15,000 lbf)|
|Specific impulse||286 s|
|Burn time||87 s|
In the early 1980s, all United States expendable launch vehicles were planned to be phased out in favor of the Space Shuttle, which would be responsible for all government and commercial launches. Production of Delta, Atlas-Centaur, and Titan 34D had ended. The Challenger disaster of 1986 and the subsequent halt of Shuttle operations changed this policy, and President Ronald Reagan announced in December of that year that the Space Shuttle would no longer launch commercial payloads, and NASA would seek to purchase launches on expendable vehicles for missions that did not require crew or Shuttle support.
McDonnell Douglas, at that time the manufacturer of the Delta family, signed a contract with the U.S. Air Force in 1987 to provide seven Delta IIs. These were intended to launch a series of Global Positioning System (GPS) Block II satellites, which had previously been manifested for the Space Shuttle. The Air Force exercised additional contract options in 1988, expanding this order to 20 vehicles, and NASA purchased its first Delta IIs in 1990 for the launch of three Earth-observing satellites. The first Delta II launch occurred on 14 February 1989, with a Delta 6925 boosting the first GPS Block II satellite (USA-35) from Launch Complex 17A (SLC-17A) at Cape Canaveral into a 20,000 km high Medium Earth orbit.
The first Delta II 7000-series flew in 1990, replacing the RS-27 engine of the 6000-series with the more powerful RS-27A. Additionally, the steel-cased Castor 4A solid boosters of the 6000 series were replaced with the composite-cased GEM-40. All further Delta II launches except three were of this upgraded configuration, and the 6000-series was retired in 1992.
McDonnell Douglas began Delta III development in the mid-90s as increasing satellite mass required more powerful launch vehicles. Delta III, with its liquid hydrogen second stage and more powerful GEM-46 boosters, could bring twice as much mass as Delta II to geostationary transfer orbit, but a string of two failures and one partial failure, along with the development of the much more powerful Delta IV, led to the cancellation of Delta III program. The upgraded boosters would still find use on the Delta II, leading to the Delta II Heavy.
On March 28, 2003, the Air Force Space Command began the process for deactivating the Delta II launch facilities and infrastructure at Cape Canaveral once the last of the second-generation GPS satellites were launched. However, in 2008, it instead announced that it would transfer all the Delta II facilities and infrastructure to NASA to support the launch of the Gravity Recovery and Interior Laboratory (GRAIL) in 2011.
The last GPS launch aboard a Delta II, and the final launch from SLC-17A at Cape Canaveral was in 2009. The GRAIL Launch in 2011 marked the last Delta II Heavy launch and the last from Florida. The final five launches would all be from Vandenberg Air Force Base (AFB) in California.
On July 16, 2012 NASA selected the Delta II to support the Orbiting Carbon Observatory OCO-2, Soil Moisture Active Passive (SMAP), and Joint Polar Satellite System JPSS-1 (NOAA-20) missions. This marked the final purchase of Delta IIs. OCO-2 was launched on July 2, 2014, SMAP was launched on January 31, 2015, and JPSS-1 was launched on November 18, 2017. All three of these launches were placed into orbit from Complex 2 at Vandenberg.
The Delta II family launched 155 times. Its only unsuccessful launches were Koreasat 1 in 1995, and GPS IIR-1 in 1997. The Koreasat 1 launch was a partial failure caused by one booster not separating from the first stage, which resulted in the satellite being placed in a lower than intended orbit. By using reserve fuel, it was able to achieve its proper geosynchronous orbit and operated for 10 years. The GPS IIR-1 was a total loss as the Delta II exploded 13 seconds after launch. The explosion occurred when a damaged solid rocket booster casing ruptured and triggered the vehicle's flight termination system. No one was injured, and the launch pad itself was not seriously impacted, though several cars were destroyed and a few buildings were damaged.
In 2007, Delta II completed its 75th consecutive successful launch, surpassing the 74 consecutive successful launches of the Ariane 4. With the launch of ICESat-2 in 2018, Delta II reached 100 consecutive successful launches.
While all completed Delta II rockets have launched, many flight-qualified spare parts remain. These spare parts will be assembled to create a nearly-complete Delta II, for exhibition in its 7420-10 configuration. The rocket will be displayed vertical at the Kennedy Space Center Visitors Complex, and may bear its popular "shark teeth" livery on its fairing, which was painted on past Delta II rockets for the GPS launches.
The first stage of the Delta II was propelled by a Rocketdyne RS-27 main engine burning RP-1 and liquid oxygen. This stage was technically referred to as the "Extra-Extended Long Tank Thor", a derivative of the Thor ballistic missile as were all Delta rockets until the Delta IV. The RS-27 used on the 6000-series Delta II produced 915 kN, while the upgraded RS-27A used by the 7000-series produced 1,054 kN. The stage was 26 meters long and 2.4 meters wide, weighted over 100 t when fueled, and burned for 260 seconds. In addition, two LR101-NA-11 vernier engines provided guidance for the first stage.
For additional thrust during launch, the Delta II used solid boosters. For the 6000-series, Delta II used Castor 4A boosters, while the 7000-series used Graphite-Epoxy Motors manufactured by ATK. The vehicle could be flown with three, four, or, most commonly, nine boosters. When three or four boosters were used, all ignited on the ground at launch, while models that used nine boosters would ignite six on the ground, then the remaining three in flight after the burnout and jettison of the first six.
The second stage of Delta II was the Delta-K, powered by a restartable Aerojet AJ10-118K engine burning hypergolic Aerozine-50 and N2O4. These propellants are highly toxic and corrosive, and once loaded the launch had to occur within approximately 37 days or the stage would have to be refurbished or replaced. This stage also contained a combined inertial platform and guidance system that controlled all flight events. The Delta-K stage was 6 meters long and 2.4 meters wide, containing up to 6 t of propellant, and burned for up to 430 seconds.
For low Earth orbit, Delta II was not equipped with a third stage. Payloads bound for higher energy orbits such as GTO or to reach Earth escape velocity for trans-Mars injection or other destinations beyond Earth used a solid propellant third stage. This stage was spin-stabilized and depended on the second stage for proper orientation prior to stage separation, but was sometimes equipped with a nutation control system to maintain proper spin axis. It also included a yo-weight system to induce tumbling in the third stage after payload separation to prevent recontact, or a yo-yo de-spin mechanism to slow the rotation before payload release.
The Delta II family used a four-digit system to generate its technical names:
For example, a Delta 7925H-10L used an RS-27A, nine GEM-46 boosters, a PAM third stage, and a lengthened 10ft diameter fairing. A Delta 6320-9.5 is a two-stage vehicle with an RS-27 first stage engine, three Castor 4A boosters, a 9.5ft diameter fairing, and no third stage.
In 2008 ULA indicated that it had "around half a dozen" unsold Delta II rockets on hand, but ULA CEO Tory Bruno stated in October 2017 that there are no complete, unbooked Delta II rockets left in the ULA inventory; and though there are leftover Delta II parts, there are not enough to build another launch vehicle. The remaining pieces will be used to create a museum piece for the Smithsonian.
The only person on record ever hit by space debris was hit by a piece of a Delta II rocket. Lottie Williams was exercising in a park in Tulsa on January 22, 1997 when she was hit in the shoulder by a six-inch piece of blackened metallic material. U.S. Space Command confirmed that a used Delta II rocket from the April 1996 launch of the Midcourse Space Experiment had crashed into the atmosphere 30 minutes earlier. The object tapped her on the shoulder and fell off harmlessly onto the ground. Williams collected the item and NASA tests later showed that the fragment was consistent with the materials of the rocket, and Nicholas Johnson, the agency's chief scientist for orbital debris, believes that she was indeed hit by a piece of the rocket.
Media related to Delta II at Wikimedia Commons
2001 Mars Odyssey is a robotic spacecraft orbiting the planet Mars. The project was developed by NASA, and contracted out to Lockheed Martin, with an expected cost for the entire mission of US$297 million. Its mission is to use spectrometers and a thermal imager to detect evidence of past or present water and ice, as well as study the planet's geology and radiation environment. It is hoped that the data Odyssey obtains will help answer the question of whether life existed on Mars and create a risk-assessment of the radiation that future astronauts on Mars might experience. It also acts as a relay for communications between the Mars Science Laboratory, and previously the Mars Exploration Rovers and Phoenix lander, to Earth. The mission was named as a tribute to Arthur C. Clarke, evoking the name of 2001: A Space Odyssey.Odyssey was launched April 7, 2001, on a Delta II rocket from Cape Canaveral Air Force Station, and reached Mars orbit on October 24, 2001, at 02:30 UTC (October 23, 19:30 PDT, 22:30 EDT).By December 15, 2010, it broke the record for longest serving spacecraft at Mars, with 3,340 days of operation. It is currently in a polar orbit around Mars with a semi-major axis of about 3,800 km or 2,400 miles. It has enough propellant to function until 2025.Aqua (satellite)
Aqua (EOS PM-1) is a NASA scientific research satellite in orbit around the Earth, studying the precipitation, evaporation, and cycling of water. It is the second major component of the Earth Observing System (EOS) preceded by Terra (launched 1999) and followed by Aura (launched 2004).
The name "Aqua" comes from the Latin word for water. The satellite was launched from Vandenberg Air Force Base on May 4, 2002, aboard a Delta II rocket. Aqua is on a Sun-synchronous orbit. It flies as the third in the satellite formation called the "A Train" with several other satellites (OCO-2, the Japanese GCOM W1, CALIPSO, CloudSat, and Aura).CALIPSO
CALIPSO is a joint NASA (USA) and CNES (France) environmental satellite, built in the Cannes Mandelieu Space Center, which was launched atop a Delta II rocket on April 28, 2006. Its name stands for Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations.
Passive and active remote sensing Instruments on board the CALIPSO satellite monitor aerosols and clouds 24 hours a day. CALIPSO is part of the "A Train", flying in formation with several other satellites (Aqua, Aura and CloudSat).Cape Canaveral Air Force Station Space Launch Complex 17
Cape Canaveral Air Force Station Space Launch Complex 17 (SLC-17), previously designated Launch Complex 17 (LC-17), was a launch site at Cape Canaveral Air Force Station, Florida used for Thor and Delta rocket launches between 1958 and 2011.
It was built in 1956 for use with the PGM-17 Thor missile, the first operational ballistic missile in the arsenal of the United States. More recently the launch complex has been used for vehicles in the Delta rocket family, derived from the Thor missile, to launch probes to the Moon and planets, solar observatories and weather satellites.
SLC-17 features two expendable launch vehicle (ELV) launch pads, 17A and 17B. The pads were operated by the US Air Force's 45th Space Wing and have supported more than 300 Department of Defense, NASA and commercial missile and rocket launches. Following the last military launch, in August 2009, SLC-17A was withdrawn from use, and SLC-17B was transferred to NASA for two remaining launches.
Pad 17A supported its first Thor missile launch on 3 August 1957, and Pad 17B supported its first Thor launch on 25 January 1957. The site was upgraded in the early 1960s to support a variety of more modern ELVs, which were derived from the basic Thor booster. The modern ELVs based on Thor came to be called the Delta family of rockets.
Thirty-five early Delta rocket missions were launched from Complex 17 between the beginning of 1960 and the end of 1965. At that time the complex was operated by the Air Force. The Air Force transferred Complex 17 to NASA in 1965, but the site was returned to the Air Force in 1988 to support the Delta II program.
As Delta II launches continued over the next decade, Pad 17B was modified in 1997 to support a new, more powerful launch vehicle, the Delta III, which made its maiden flight from the complex on 26 August 1998. The launch ended in failure, as did a second launch the next year. After a third launch on 23 August 2000 placed a mass simulator into a lower than planned orbit, the program was abandoned.
Among the major NASA missions launched from the complex were the Explorer and Pioneer space probes, all of the Orbiting Solar Observatories, the Solar Maximum Mission, Biological Satellites (BIOS), the International Cometary Explorer, the TIROS and GOES meteorology satellites, and the Mars Exploration Rovers Spirit and Opportunity.
On 10 September 2011, a Delta II 7920H-10C made the final launch from Space Launch Complex 17, carrying NASA's GRAIL spacecraft. All remaining Delta II launches will be made from Vandenberg Air Force Base in California.
At 7am EDT (1100 GMT) on 12 July 2018, both historic launch towers had been demolished via controlled demolition to make way for Moon Express to build and test its lunar lander.CloudSat
CloudSat is a NASA Earth observation satellite, which was launched on a Delta II rocket on April 28, 2006. It uses radar to measure the altitude and properties of clouds, adding to information on the relationship between clouds and climate in order to help resolve questions about global warming.CloudSat flies in formation in the "A Train", with several other satellites including Aqua, Aura, and CALIPSO. It has been in daytime-only operations since 2011 due to battery malfunction, requiring sunlight to power the radar.
The mission was selected under NASA's Earth System Science Pathfinder program in 1999. Ball Aerospace & Technologies Corp. in Boulder, Colorado, designed and built the spacecraft.
CloudSat's primary mission was scheduled to continue for 22 months in order to allow more than one seasonal cycle to be observed.Delta-class submarine
The Delta class (Project 667B Murena, Project 667BD Murena-M, Project 667BDR Kalmar, Project 667BDRM Delfin) is a common name for a set of four types of submarines which formed the backbone of the Soviet and Russian strategic submarine fleet since their introduction in 1973. They carry nuclear ballistic missiles of the R-29 Vysota family, with the Delta I, Delta II, Delta III and Delta IV classes carrying the R-29 (NATO reporting name: SS-N-8 'Sawfly'), R-29D (SS-N-8 'Sawfly'), R-29R (SS-N-18 'Stingray') and R-29RM (SS-N-23 'Skiff') respectively. The Delta I class carried 12 missiles, while the Delta II class which are lengthened versions of the Delta I class carry 16 missiles. The Delta III and Delta IV classes carry 16 missiles with multiple warheads and have improved electronics and noise reduction.
The R-27 Zyb missile carried by the Project 667s of the late 1960s had a range of 2,500–3,000 km (1,553–1,864 mi), so the earlier submarines were forced to patrol close to the North American coast, whereas the Deltas could launch the over 7,700 km (4,785 mi)-range R-29s from the relative safety of the Arctic Ocean. In turn the Deltas were superseded by the larger Typhoon-class submarines. The early Deltas remained in service until the 1990s with treaties such as START I. High running costs and the retirement of the Typhoons' R-39 missiles meant that some Delta III-class submarines were reactivated in the 2000s (decade) to replace the Typhoons.
In December 2010 Pavel Podvig and russianforces.org estimated the strength of the Russian strategic submarine fleet at one Typhoon-class submarine (used to test the R-30 Bulava missile), four Delta III, six Delta IV class, and one Borei class. They will ultimately be replaced by the new Borei-class submarines (also known as the Dolgorukiy class).Delta (rocket family)
Delta is an American versatile family of expendable launch systems that has provided space launch capability in the United States since 1960. There have been more than 300 Delta rockets launched, with a 95% success rate. Only the Delta IV remains in use as of 2018. Delta rockets are currently manufactured and launched by the United Launch Alliance.Delta III
The Delta III rocket was an expendable launch vehicle made by Boeing. The first Delta III launch was on August 26, 1998. Of its three flights, the first two were failures, and the third, though declared successful, reached the low end of its targeted orbit range and carried only a dummy (inert) payload. The Delta III could deliver up to 8,400 pounds (3,800 kilograms) to geostationary transfer orbit, twice the payload of its predecessor, the Delta II. Under the 4-digit designation system from earlier Delta rockets, the Delta III is classified as the Delta 8930.Extreme Ultraviolet Explorer
The Extreme Ultraviolet Explorer (EUVE) was a space telescope for ultraviolet astronomy, launched on June 7, 1992. With instruments for ultraviolet (UV) radiation between wavelengths of 7 and 76 nm, the EUVE was the first satellite mission especially for the short-wave ultraviolet range. The satellite compiled an all-sky survey of 801 astronomical targets before being decommissioned on January 31, 2001. It re-entered the atmosphere on January 30, 2002.Far Ultraviolet Spectroscopic Explorer
The Far Ultraviolet Spectroscopic Explorer (FUSE) is a space-based telescope operated by the Johns Hopkins University Applied Physics Laboratory. FUSE was launched on a Delta II rocket on 24 June 1999, as a part of NASA's Origins program. FUSE detected light in the far ultraviolet portion of the electromagnetic spectrum, between 90.5-119.5 nanometres, which is mostly unobservable by other telescopes. Its primary mission was to characterize universal deuterium in an effort to learn about the stellar processing times of deuterium left over from the Big Bang.
FUSE resides in a low Earth orbit, approximately 760 km (410 nmi) in altitude, with an inclination of 25 degrees and just less than a 100-minute orbital period. Its Explorer designation is Explorer 77.
On 12 July 2007, FUSE's final reaction wheel, which is required for accurately pointing a spacecraft, failed and efforts to restart it were unsuccessful. An announcement was made on 6 September that because the fine control needed to perform its mission had been lost, the FUSE mission would be terminated.GM Delta platform
Delta is General Motors' compact front-wheel drive automobile and crossover SUV platform, a successor to the GM T platform; it also replaced GM J platform and the Z platform used by the Saturn S-Series. The platform debuted in the 2003 Saturn Ion. Vehicles of this platform generally carry the letter "A" in the fourth character of their VINs.
Delta uses an independent suspension in front and Twist beam type in the rear. The Ecotec engine is widely used, as are a 4-speed automatic and 5-speed manual transmission.GPS IIR-1
GPS IIR-1 or GPS SVN-42 was the first Block IIR GPS satellite to be launched. It was to have been operated as part of the United States Air Force Global Positioning System. It was launched on January 17, 1997, and was destroyed 13 seconds into its flight due to a malfunction of the Delta II rocket that was carrying it. It was estimated to have cost US$40 million, with its carrier rocket costing $55 million. The satellite that was used for the IIR-1 mission was the second production IIR satellite, SVN-42.Geotail
Geotail is a satellite observing the Earth's magnetosphere. It was developed by Japan's ISAS in association with the United States' NASA, and was launched by a Delta II rocket on July 24, 1992.
The Geotail satellite was launched on July 24, 1992, by a Delta II launch vehicle from Cape Canaveral Air Force Station, Florida, United States. The primary purpose of this mission is to study the structure and dynamics of the tail region of the magnetosphere with a comprehensive set of scientific instruments. For this purpose, the orbit has been designed to cover the magnetotail over a wide range of distances: 8 R⊕ to 210 R⊕ from the earth. This orbit also allowed it to study the boundary region of the magnetosphere as it skims the magnetopause at perigees. In the first two years the double lunar swing-by technique was used to keep apogees in the distant magnetotail. This involved 14 lunar flybys.In 1993 the computer that controls the Low Energy Particles experiment locked up. Attempts to reset it failed. This problem was solved by changing the trajectory of the craft during a lunar flyby that took place on 26 September 1993 so that it passed through the shadow of the moon. Power from the batteries was cut while this took place. When the craft left the shadow the moon and power returned the computer started working again.The apogee was lowered down to 50 R⊕ in mid November 1994 and then to 30 R⊕ in February 1995 in order to study substorm processes in the near-Earth tail region. The present orbit is 9 R⊕ × 30 R⊕ with inclination of -7° to the ecliptic plane."
Geotail instruments studied electric fields, magnetic fields, plasmas, energetic particles, and plasma waves.In 1994 the principal investigator of the Plasma Wave Instrument (PWI), the experiment complement, was Professor Hiroshi Matsumoto of Kyoto University, with co-investigators from NASA, the University of Iowa, and STX Corporation.
Geotail is an active mission as of 2018. Geotail, WIND, Polar, SOHO, and Cluster were all part of the International Solar-Terrestrial Physics Science Initiative (ISTP) project.Graphite-Epoxy Motor
A Graphite-Epoxy Motor (GEM) is a solid-fuel rocket motor (SRM) produced by Northrop Grumman (Formerly Orbital ATK) with an epoxy composite casing. GEM boosters have been used on the Delta II, Delta III, and Delta IV, and are planned for future use on the Atlas V, Vulcan, and Orbital ATK’s proposed Omega.ICESat-2
ICESat-2 (Ice, Cloud, and land Elevation Satellite 2), part of NASA's Earth Observing System, is a satellite mission for measuring ice sheet elevation and sea ice thickness, as well as land topography and vegetation characteristics. ICESat-2, a follow-on to the ICESat mission, was launched on 15 September 2018 from Vandenberg Air Force Base in California, into a near-circular, near-polar orbit with an altitude of approximately 496 km (308 mi). It was designed to operate for three years and carry enough propellant for seven years.The ICESat-2 mission is designed to provide elevation data needed to determine ice sheet mass balance as well as vegetation canopy information. It will provide topography measurements of cities, lakes and reservoirs, oceans and land surfaces around the globe, in addition to the polar-specific coverage.
The ICESat-2 project is being managed by Goddard Space Flight Center in Greenbelt, Maryland. The sole instrument was designed and built by the center, and the bus was built by and integrated with the instrument by Orbital Sciences (later Orbital ATK). The satellite was launched on a Delta II rocket provided by United Launch Alliance. This was the last launch of the Delta II rocket.List of GPS satellites
As of December 2018, 73 Global Positioning System navigation satellites have been launched, 31 of which are operational, 9 in reserve, 1 being tested, 30 have been retired and 2 were lost at launch. The constellation requires a minimum of 24 operational satellites, and the official target count is 33.SVNs are "space vehicle numbers" which are serial numbers assigned to each GPS satellite. PRNs are the "pseudo-random noise" sequences, or Gold codes, that each satellite transmits to differentiate itself from other satellites in the active constellation.List of Thor and Delta launches
This is a list of launches made by the PGM-17 Thor IRBM, and its derivatives, including the Delta family and the Japanese N-I, N-II and H-I rockets which were based on license-produced components. Between 2005 and February 2018, rockets in this family have flown 69 consecutive missions without failure. Due to the size of the list, it has been split into several smaller articles:
List of Thor and Delta launches (1957–59)
List of Thor and Delta launches (1960–69)
List of Thor and Delta launches (1970–79)
List of Thor and Delta launches (1980–89)
List of Thor and Delta launches (1990–99)
List of Thor and Delta launches (2000–09)
List of Thor and Delta launches (2010–19)List of USA satellites
This is a list of satellites and spacecraft which have been given USA designations by the United States Air Force. These designations have been applied to most US military satellites since 1984, and replaced the earlier OPS designation. It is comparable to the Soviet/Russian Kosmos designation.
As of December 2018, USA designations have been assigned to 290 space missions. Note that there is not always a one-to-one mapping between launch vehicles and mission spacecraft. This can occasionally result in gaps when maintaining records that incorrectly make that assumption, such as the "missing" entries for USA-163 (which are, symmetrically, contemporary with confusion over "splitting" spacecraft tracks).USA-206
USA-206, also GPS SVN-50, PRN-05 and NAVSTAR 64 and known before launch as GPS IIR-21, GPS IIRM-8 or GPS IIR-21(M), is an American navigation satellite which forms part of the Navstar Global Positioning System. It was the twenty-first and last Block IIR GPS satellite to be launched, and the eighth to use the modernised IIRM configuration.GPS IIR-21 was built by Lockheed Martin, based on the AS-4000 satellite bus, with the navigation payload being built by ITT. It was launched by a United Launch Alliance Delta II rocket, using the 7925-9.5 configuration, on 17 August 2009 at 10:35 GMT. It was the last spacecraft to launch from Space Launch Complex 17A at the Cape Canaveral Air Force Station, a launch pad which was first used in August 1957 for test flights of the PGM-17 Thor missile. It is also the final flight of an AS-4000 bus, the final GPS launch on a Delta II, and the final Delta II launch to be overseen by the US Air Force.Following separation from its carrier rocket, GPS IIR-21 received its USA designation, USA-206. It was deployed into a transfer orbit, from which raised itself to a semi-synchronous medium Earth orbit on 19 August, using an onboard Star 37FM apogee motor. It is a 2,032-kilogram (4,480 lb) satellite, and is expected to operate for at least ten years. Once it had completed on-orbit testing, it began covering Slot 3 of Plane E of the GPS constellation, replacing USA-126, or GPS IIA-26, which was launched in July 1996. It was declared operational on 27 August 2009.