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Saturday, October 6, 2012

Launch GPS IIF-3 (Delta IV M +)

On Thursday, October 4 at 12:10 UTC, the company ULA (United Launch Alliance) launched a Delta IV M + (4, 2) from SLC-37 slope to Cape Canaveral. On board was the GPS IIF-3 satellite (USA-239) global positioning system GPS. Apparently, the motor RL-10 of the second stage experienced some problems during power up.


The GPS IIF-3, Navstar 2F-3 or 65 is the third satellite of the fourth generation of GPS satellites, the IIF. It has a mass of 1630 kg and is manufactured by Boeing, but is operated by the Air Force (USAF). The IIF series replaces the IIR and IIRM satellites, the last of which was released in 2009. Each satellite has dimensions of 2.49 x 2.03 x 2.24 m and is equipped with two rubidium atomic clocks and one cesium. The GPS IIF issued two new types of signals from a total of four, one military (M-code, more resistant to interference, divided into two frequencies: L1M and L2M) and other civil (L5, which was already tested with the satellite USA-203). Like the rest of GPS civil signal will also issue the L2C. Your life is estimated at 12 years and does not need a apogee engine to reach orbit. The satellite is expected to replace the GPS IIA-2 (USA-71), released in 1991. In 1996, Boeing signed a contract to build twelve units IIF. In principle should be 33, but in 2001 it was decided to replace the IIF series GPS IIIA family, whose first issue will be released in 2014.

The network of global positioning GPS uses 24 satellites in six different orbital planes, with a minimum of four satellites per plane, located about 17 700 km altitude. The constellation is in charge of the 50th Space Wing of the USAF, located at Schreiber, Colorado.

Delta IV M + (4,2)

The Delta IV M + (4,2) is a two-stage rocket with a capacity in low orbit (LEO) of 10 430 kg or 5845 kg into geostationary transfer orbit (GTO). This is a series EELV launcher Delta IV with one CBC (Common Booster Core) in the first stage, a second stage of four meters in diameter, also a cap of 4 meters and two solid rockets SRM (Solid Rocket Motor) GEM-60. Employs hydrogen and liquid oxygen in two stages and, like the Atlas V, is based on a modular design to accommodate different payloads according to several versions of the launcher.

The first stage cryogenic engine uses the RS-68 (manufactured by Pratt & Whitney Rocketdyne). The RS-68 was designed during the 90's and has a vacuum thrust of 3312 kN, much higher than the SSME (2278 kN), which makes it the most powerful cryogenic engine in history.

The second stage of the Delta M + (4,2) is based on the Delta III and uses a motor RL10B-2 , also manufactured by Pratt & Whitney Rocketdyne, with a thrust of 110 kN and a specific impulse of 462 s. This engine is based on the venerable RL-10 developed in the late 50's and has also been used in the Atlas rocket and Centaur stage.

The Delta IV M + (4.2) uses two SRM manufactured by Alliant Techsystems, also known as GEM-60 (Graphite-Epoxy Motors), based on GEM-46 Delta III. They work for 90 seconds and are 1.5 meters in diameter, a thrust of 826.6 kN and a specific impulse of 275 s each.

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