will begin anechoic tests this week of the GPS non-flight satellite testbed (GNST), an engineering, manufacturing and development pathfinder for the future constellation.
The tests pave the way for follow-on thermal vacuum chamber evaluation of the GNST, which is at the halfway point in its development. The non-flying tes€₤tbed, introduced by the U.S. Air Force specifically to avoid development issues and delays to follow-on operational spacecraft, is already proving its worth, says Keoki Jackson, Lockheed Martin’s navigation systems vice president.
“GPS IIR was seven and a half years from authority to proceed [ATP] to first launch, and that was a simpler spacecraft half the size of GPS III. From ATP to readiness to launch for GPS III will be six years,” Jackson says. The pre-production GNST is “finding all the kinks” ahead of the operational craft, he adds.
“We have been able to reduce the number of suspended load lifts by 50%, and the number of moves from location to location have been reduced by 50%,” he says. In previous programs “we used up a bit of schedule margin when we were going through the first article.” However, because of the GNST “the span for mechanical integration is about right on,” he adds.
The first flyable GPS III, SV-01, is now following the GNST down the assembly line at Lockheed Martin’s Denver facility. The solar arrays for the second operational unit, SV-02, also have arrived at the site, where assembly of the craft itself is due to begin in early 2014. The facility, which is made up of 16 stations on the production floor, is sized for up to four GPS IIIs per year at the current funding level and will be processing spacecraft at the rate of only two per year.
The GNST will be shipped to Cape Canaveral around the third quarter of this year. The pathfinder will complete its task when it has been used for demonstrating stacking and pre-launch integration.
Lockheed Martin remains on contract to have the first GPS III available for launch by May 2014, although the Air Force initial operational requirement is not until 2015. The Air Force and Lockheed Martin are discussing, however, the merits of launching SV-01 earlier to validate the vehicle and establish whether the advanced satellite and its systems are fault-free.