 A Delta II rocket launches from Cape Canaveral carrying the Dawn spacecraft. |
|
| Function | Launch vehicle |
|---|---|
| Manufacturer | United Launch Alliance (Boeing IDS) |
| Country of origin | United States |
| Cost per launch (1987) | US$36.7 million |
| Size | |
| Height | 38.2 - 39 m (125.3 - 127 ft) |
| Diameter | 2.44 m (8 ft) |
| Mass | 151,700 - 231,870 kg (334,300 - 511,180 lb) |
| Stages | 2 or 3 |
| Capacity | |
| Payload to LEO |
2,700 - 6,100 kg (5,960 - 13,440 lb) |
| Payload to GTO |
900 - 2,170 kg (1,980 - 4,790 lb) |
| Payload to HCO |
1,000 kg (2,200 lb) |
| Launch history | |
| Status | Active |
| Launch sites | Cape Canaveral SLC-17 Vandenberg AFB SLC-2W |
| Total launches | 146 Delta 6000: 17 Delta 7000: 123 Delta 7000H: 5 |
| Successes | 144 Delta 6000: 17 Delta 7000: 121 Delta 7000H: 5 |
| Failures | 1 (Delta 7000) |
| Partial failures | 1 (Delta 7000) |
| Maiden flight | Delta 6000: 14 February 1989 Delta 7000: 26 November 1990 Delta 7000H: 8 July 2003 |
| Last flight | Delta 6000: 24 July 1992 |
| Boosters (6000 Series) - Castor 4A | |
| No boosters | 3, 4 or 9 |
| Engines | 1 Solid |
| Thrust | 478.3 kN (107,530 lbf) |
| Specific impulse | 266 sec |
| Burn time | 56 seconds |
| Fuel | Solid |
| Boosters (7000 Series) - GEM 40 | |
| No boosters | 3, 4 or 9 |
| Engines | 1 Solid |
| Thrust | 492.9 kN (110,800 lbf) |
| Specific impulse | 274 sec |
| Burn time | 64 seconds |
| Fuel | solid |
| Boosters (7000 Heavy) - GEM 46 | |
| No boosters | 9 |
| Engines | 1 solid |
| Thrust | 628.3 kN (141,250 lbf) |
| Specific impulse | 278 sec |
| Burn time | 75 seconds |
| Fuel | solid |
| First stage - Thor/Delta XLT-C | |
| Engines | 1 RS-27A[1] |
| Thrust | 1,054.2 kN (237,000 lbf) |
| Specific impulse | 302 sec |
| Burn time | 265 seconds |
| Fuel | RP-1/LOX |
| Second stage - Delta K | |
| Engines | 1 AJ-10 |
| Thrust | 43.6 kN (9,800 lbf) |
| Specific impulse | 319 sec |
| Burn time | 431 seconds |
| Fuel | Dinitrogen tetroxide/Aerozine |
| Third stage - PAM-D (optional) | |
| Engines | 1 Star 48B |
| Thrust | 66.0 kN (14,837 lbf) |
| Specific impulse | 286 sec |
| Burn time | 87 seconds |
| Fuel | Solid |
Delta II is a space launch system originally designed and built by McDonnell Douglas. Delta II is part of the Delta rocket family and has been in service since 1989. Delta II vehicles include the retired Delta 6000, the active Delta 7000, and two 7000 variants (light and heavy).
Delta II rockets were later built by Boeing Integrated Defense Systems until Delta rocket production became the responsibility of United Launch Alliance (ULA) on December 1, 2006.[2][3] ULA now markets Delta II to U.S. government customers, and Boeing Launch Services (BLS) markets Delta II to commercial companies.[4]
Contents |
All United States expendable launch vehicles were to be phased out for the Space Shuttle, but in 1986 the Challenger accident restarted Delta development. The Delta II was specifically designed to accommodate the GPS Block II series of satellites. Delta IIs have successfully launched 125 projects (through August 2007), including several NASA missions to Mars:
Delta II manufacturing, assembly and integration currently take place in Decatur, Alabama; Harlingen, Texas; San Diego, California; and Denver, Colorado.[4]
Deltas are expendable launch vehicles (ELVs), which means they are used only once. Each Delta II launch vehicle consists of:
The Delta II family is more technically named by a four-digit system:[6]
For example, a Delta 7925 has the later first stage, nine GEM boosters, and a PAM third stage. A Delta 7320 is a two-stage vehicle with three boosters.
Three payload fairings are available. The original aluminum fairing, seen above, is 9.5 feet in diameter. A 10-foot fairing is made of composite, and can be distinguished by its tapering front and rear. A lengthened 10-foot fairing is used for the largest payloads.
The Delta II system has been used for 146 launches. On September 18, 2007, Delta II completed its 75th consecutive successful launch.[9] This is a record for modern launch vehicles.[10] It is the most reliable launch vehicle currently in service, behind the (now retired) Tsyklon 2.[11] Eight launches took place in 2007.
However, the Delta II system does not have a perfect success record. One mission, the launch of Koreasat-1, was a partial failure in which the satellite payload was able to compensate when the launch system placed the vehicle in an incorrect orbit.[12]
Another failure, this time complete, occurred on January 17, 1997, when a Delta II 7925 carrying the first GPS Block IIR satellite, GPS IIR-1, exploded only 13 seconds after liftoff, raining flaming debris all over Launch Complex 17 at Cape Canaveral Air Force Station. No one was injured, and the launchpad itself was not seriously damaged, though several cars were destroyed and a few buildings were damaged.[13] It was later determined that a "17-foot crack" in the rocket booster had caused the failure.[14]
A third partial failure was an Iridium payload 77, which was "in pieces" in orbit after launch (according to Don Gillies, Payload Systems Engineer) in September 1998.[15]
Between May 1997 and November 1998 Delta II vehicles placed 55 Iridium satellites into orbit.[16]
An article published by the Wall Street Journal speculates about the fate of the Delta II launch system after U.S. Air Force discontinues its use of the Delta II.[17] Thomas Young, who was director of Goddard Space Flight Center from 1980 to 1982, is quoted as saying, "It's definitely an item people are quite worried about."
The final payload currently scheduled for Delta II is a NASA moon mission in 2011.[18] ULA has indicated it has "around half a dozen" unsold Delta II rockets on hand.[19] A spokesperson indicated ULA will change some aspects of the Delta II system once the current Medium Launch Vehicle 3 contract with the Air Force ends and requirements imposed by the contract are lifted. The Air Force contract required that Delta II be kept ready to launch within 40 days of call up, which led ULA to maintain two launch pads at Cape Canaveral. ULA indicated it would not continue to operate two launch pads.[19]
In August 2009 the NASA assistant associate administrator for launch services indicated NASA might purchase additional Delta II launches beyond those it currently has planned.[20] Seven Delta II flights are planned through 2011. Five additional Delta II vehicles have been built but remain unassigned to planned flights.
The Aerojet-built second-stage engine has been chosen by NASA to be used as the main propulsion engine for the Orion spacecraft that will replace the Space Shuttle after 2010. The engine was chosen due to its restart capabilities along with a switch from the original liquid oxygen/liquid methane (LOX/LCH4) application to hypergolic fuel and oxidizer similar to that in use on the Shuttle's OMS and RCS systems.
Media related to Delta (Rocket) at Wikimedia
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   | History of the Delta Launch Vehicle - History of the Delta Launch Vehicle |
| | Article about 1997 failed launch and self-destruction (with video) - CNN - Unmanned rocket explodes after liftoff - Jan. 17, 1997 |
| | Boeing Delta II Page - Boeing: Integrated Defense Systems - Network & Space Systems - Boeing Launch Services - Delta II Overview |
| | Expendable Launch Vehicle Status Report - NASA - Expendable Launch Vehicle Status Report |
| | Delta II's Fate Worries Nonmilitary Users - Delta II's Fate Worries Nonmilitary Users - WSJ.com |
| | DigitalGlobe Successfully Launches Worldview-1 - DigitalGlobe | Press Room - News Room |
| | Mission Status Center (Delta 326) - Spaceflight Now | Delta Launch Report | Mission Status Center |
| | Swift Launch Pad Activities - NASA - Swift Launch Pad Activities |
| | Koreasat 1, 2 (Mugungwha 1, 2) / Europe*Star B - Koreasat 1, 2 (Mugungwha 1, 2) / Europe*Star B / ABS 1A |
| | Boeing Delta II to Launch New Additions to Iridium Constellation - Boeing: Boeing Delta II to Launch New Additions to Iridium Constellation |
| | Webcast - NASA - NASA TV |
| | History of the Delta Launch Vehicle - History of the Delta Launch Vehicle |
| | Boeing IDS Page - Boeing: Integrated Defense Systems - Boeing Launch Services - Delta |
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