Friday’s expected launch of the Air Force’s seventh Global Positioning System IIF series (GPS IIF-7) satellite will be its last using C-band tracking radar to track the Atlas V launch vehicle.
GPS IIF-7 Mission Director Walter Lauderdale said Friday during a teleconference that the launch will be the last to not use GPS metric tracking as opposed to radar tracking. The GPS IIF-7 launch will take place at Cape Canaveral Air Force Station, Fla. Issues with a tracking radar at Cape Canaveral in March caused delays for both military and commercial launch customers.
Lauderdale said Friday’s launch with radar tracking will have two radars in use for the mission and that both are checked out and fully operational. Lauderdale also said starting with the August 13 launch of DigitalGlobe’s [DGI] WorldView-3 launch from Vandenberg AFB, Calif., Atlas V launch vehicle tracking will solely be via GPS.
“We’re looking forward to that improvement,” Lauderdale said. “It’s something that’s been a long time coming.”
Lauderdale said an advantage of GPS is that radars can be susceptible to the various flight angles in terms of getting a reflection back from the vehicle. Atmospheric effects, Lauderdale said, can also influence a radar’s performance. Radar is considered an old-technology way of ensuring the safe tracking of launch vehicles as they move through earth’s atmosphere. GPS is the United States’ position, navigation and timing (PNT) system.
The move to GPS, Lauderdale said, is an Air Force Space Command (AFSPC) effort going back several years to use range assets more efficiently. He said the Air Force has been working with launch provider United Launch Alliance (ULA) to develop the GPS flight tracking capability on both the Atlas V and Delta IV launch vehicles.
GPS was successfully tested out on both coasts and on Delta and Atlas a couple of years ago, Lauderdale said, and the Air Force is simply flying out the last of its C-band radar beacons. Lauderdale said though the radars have two modes, beacon tracking and skin tracking, he didn’t know what would happen to the tracking radars after Friday’s expected launch.
Beacon tracking is for cooperative targets while skin tracking is for non-cooperative targets. C-band radar is often used by large ships that transverse oceans and require uninterrupted, dedicated, always-on connectivity as they move from region to region. C-band radar usually transmits around six gigahertz (GHz) and receives around four GHz, and is often identified by the large, white domes seen on giant sea vessels.
The tracking radar overheating in March at Cape Canaveral delayed the launch of a spy satellite 16 days. The former head of Air Force Space and Missile Systems Center (AFSMC), Lt. Gen. Ellen Pawlikowski, in May defended the service’s handling of its ranges and tracking radars, saying the range is the “culprit in slipping launches…a pretty small amount of the time.” AFSMC is responsible for the ranges at Air Force launch sites. Pawlikowski said the Air Force wants to move to GPS tracking to eliminate the redundancy of tracking radars (Defense Daily, May 22).
GPS IIF-8 is scheduled for launch October 29, also from Cape Canaveral, according to Boeing [BA] spokeswoman Diana Ball. The Air Force launched GPS IIF-6 on May 16 and the satellite became operational June 10. There will be 12 total satellites in the GPS IIF constellation, of which Boeing is the prime contractor.
Friday’s expected launch time is approximately 11:23 p.m. EDT and is contingent on a successful launch Monday post-press time of the Air Force’s Geosynchronous Space Situational Awareness Program (GSSAP) satellite. The GSSAP satellite launch has been delayed since July 23 due to an issue with the ground support equipment environmental control system and weather. Outgoing AFSPC chief Gen. William Shelton described GSSAP as a “neighborhood watch” to keep an eye on potential nefarious activities of nearby satellites.
CSR, a joint venture of PAE and Raytheon [RTN] subsidiary Raytheon Technical Services Company, is responsible for the range at Cape Canaveral.