At 5:38 PM Wednesday evening, a United Launch Alliance Atlas V rocket launched the latest Global Positioning Satellite into orbit, augmenting the space based system which has become almost inextricably entwined in daily life. Following check out in orbit, the GPS IIF-4 will become the 31st operational spacecraft currently in the system. With most GPS satellites significantly exceeding their design lives, the Air Force is carefully replacing aging “birds” while keeping a steady supply in the pipeline.
The most recent prior launch, taking place on October 4, 2012, was marred by a problem in the Delta IV launch vehicle’s upper stage which suffered a small fuel leak in its RL10B-2 engine. Due to the satellite’s comparative light weight relative to booster performance, the Delta IV was able to complete the mission successfully. After a long stand down to examine the problem, the Delta IV is scheduled to return to flight next week.
Of note, yesterday’s launch was carried out on board an Atlas V 401 variety, which is the basic booster core powered by the Russian built RD-180 main engine, and a single RL-10 upper stage engine without any solid strap-on motors for assist. Although it is the least expensive version of the Atlas, the always reliable booster is somewhat overkill for GPS satellites, many of which were launched by the more affordable Delta II before its production was cancelled by ULA. According to the GAO, units costs for the EELV program under which this launch was conducted increased from $98.8 million in 1998, to $381 million as of March 2012.
Future GPS launches are a likely candidate for new providers such as SpaceX and Orbital Science, but ULA has sought to effectively block entry by successfully persuading the Air Force to fund development of a dual launch adapter for the Atlas V on the basis of purported costs savings. As this Space News op-ed points however, the analysis is based on what can only be considered questionable numbers.