A state-of-the-art GPS satellite has been launched to replace one that has lasted more than twice as long as expected.
The satellite, built by Boeing, was carried into space aboard an unmanned Delta 4 rocket, which blasted off from Cape Canaveral Air Force Station in Florida at 1.59am this morning. Once in position, 12,000 miles above the planet, the new satellite will replace a 16-year-old member of the GPS constellation.
The 31-satellite navigation network is in constant use by the military, civilian agencies and commercial customers worldwide but many of the satellites are nearing the end of their useful lives, with eight older GPS satellites still operational.
"They're well past their design life – the oldest one is 23 years – so we've really got remarkable performance out of them," William Cooley, head of the GPS directorate at the US Air Force's Space and Missile Systems Center in Los Angeles, told reporters during a prelaunch conference call.
"Sometimes we joke that they are getting old enough to vote and some of them are old enough to drink."
The new satellite is the fifth in a next-generation series of spacecraft that beam more precise navigation signals and resist jamming. The so-called "2F" series, which are designed to last 12 years, also include signals to assist commercial aviation and support search and rescue operations.
Boeing received the satellite's first signals approximately three and a half hours after the launch and it will now undergo on-orbit activation, checkout and testing before joining the active GPS constellation.
"Boeing launched the first GPS satellite in 1978 and has played an integral role in the on-going enhancement of this vital technology ever since," said Craig Cooning, Boeing vice president and general manager of Space & Intelligence Systems.
"The 42 satellites that we have deployed into service to date for the US Air Force have accumulated more than 500 years of on-orbit operations, and the current system continues to meet or exceed all mission requirements."
Two more upgraded GPS satellites are slated for launch this year. After today's launch, the constellation will include 31 operational satellites and six older spacecraft that are kept in orbit as potential spares.
Using signals from GPS satellites, receivers can calculate positions on Earth within a metre and to a millionth of a second. The network has become a ubiquitous part of modern life, used in industries from financing to farming.
"I don't think anybody knows what all the applications of GPS are," launch commentator Mark McCullick, with the Air Force's GPS directorate, said during a webcast. "New ways to use GPS emerge every day."