New launch window set for GPS III SV04

November 2, 2020 - By Tracy Cozzens

After an aborted launch with two seconds to go, the fourth GPS III satellite is now planned to launch on Nov. 5.

The first launch attempt on Oct. 2 from Cape Canaveral was halted due to an “unexpected pressure rise in the turbomachinery gas generator,” said SpaceX CEO Elon Musk on Twitter, referring to a part in the rocket’s Merlin engines.

SpaceX test-fired the Falcon 9 rocket for the GPS mission on Saturday at 7 p.m. on pad 40 at Cape Canaveral Air Force Station to verify that corrective actions have resolved the issue, according to SpaceX and reported by SpaceFlightNow. The fourth GPS III satellite was not aboard during the test.

GPS III SV04 first rolled out to Cape Canaveral’s Space Launch Complex 40 on Sept. 27. The satellite was originally scheduled for launch Sept. 30, then Oct. 1, but that launch was delayed because of a “traffic jam” at the launchpad caused by launch delays of other rockets.

The satellite was almost launched at 9:43 p.m. EDT on Oct. 2 until the launch was stopped at T– 2 seconds.

The Lockheed Martin-built GPS III SV04 will be launched aboard a SpaceX Falcon 9 rocket — the third National Security Space Launch (NSSL) mission on a Falcon 9 rocket, the second U.S. Space Force (USSF) first-stage booster recovery, and the sixth USSF launch.

A live feed will begin 20 minutes before the launch and conclude approximately 45 minutes afterward. A simulcast of the broadcast can be viewed at www.spacex.com.

GPS III SV04 will be launched to augment the current GPS constellation comprised of 31 operational spacecraft. GPS satellites operate in Medium Earth Orbit (MEO) at an altitude of approximately 20,200 km (12,550 miles) in six orbital planes. Each satellite circles the earth twice per day.

GPS III brings new capabilities to users such as the new L1C civilian signal, which opens the window for future interoperability with international satellite navigation systems.