While the European Space Agency had to decrease power on its first four Galileo satellites, the agency will move ahead with the launch of Dorsea and Milena as its continues to step closer to finally maintaining its own array of GPS satellites.
Dorsea and Milena, names chosen for the satellites by school children, will bring the Galileo project's count of orbiting satellite to six and leave the ESA with 24 more to go to reach its goal of launching 30 into medium-earth orbit.
Dorsea and Milena have already been coupled together on a dispenser and will be rocketed into orbit by the Soyuz launcher, which launched pairs of Galileo satellites in orbit back in October of 2011 and October of 2012. The ESA expected a refurbished Ariane 5 ES launcher to be operational some time in 2014, giving the agency the ability to launch four satellites at a time.
The latest pair of satellites are set to lift off from the ESA's spaceport in French Guiana on Aug. 21 at 12:31 p.m. Greenwich Mean Time (GMT).
The FM-4, one of Galileo's first four satellites, experienced a sudden drop in power in May of 2014 that still hasn't been explained. Javier Benedicto, Galileo's program manager, said the agency explored over 40 fault scenarios to determine what caused the FM-4 to experience the drop in power, but answers remain illusive.
The FM-3 and FM-2 also suffered unrelated losses in power, though the ESA were able to pinpoint the causes of those problems, said Benedicto. To account for the loss in power across the four pilot satellites, the ESA lowered the power on all of Galileo's orbiting satellites.
"We backed off 1.5 dB (decibels) on all four spacecraft about a month ago," said Benedicto. "This was done as a precautionary measure while we are continuing to investigate, before we come to any conclusions. This is not causing any degradation of mission performance, as this was a margin we had after [the satellites'] launch. It would not be perceivable by users at this point."
After Galileo is supported by 18 orbiting satellites, the project will move from its In-Orbit Validation phase into the second half of the project. The Full Operation Capability phase of Galileo will see the ESA added more ground support for the project.
The ESA hopes to have launched 18 Galileo satellites into orbit by 2015 and to add the remaining 12 to the array by 2020.
Back Stateside, the United Launch Alliance sent GPS IIF-7 satellites to enhance the accuracy of a network composed of 24 orbiting satellites.
