A cadre ofmilitary and industry workers at the Cape Canaveral Air Force Station isreadying the first-of-its-kind satellite for the Global Positioning System, anadvanced bird that will be shipped to the launch pad and bolted atop a Delta 4rocket next week.
Liftoff of the GPS 2F-1 spacecraft from pad37B is targeted for May 21 at 11:25 p.m. EDT.
"We're getting goose bumps right now.We're very excited," said Harry Brown, the GPS 2F program's chief engineerat satellite-builder Boeing.
"There is a pride in working GPS, thereis a pride in what we do for the nation and we know this is a nationalasset."
Circling 11,000 miles overhead, the networkof GPS satellites emit continuous navigation signals that allow users to findtheir precise position in latitude, longitude and altitude and determine time.Originally built as a tool for the U.S. military, the utility has spread acrossthe world as an indispensable commercial service.
Some 60 satellites have been launched for thesystem over the past three decades, and now the AirForce is poised to deploy the initial satellite in the Block 2F series thatfeatures even higher accuracy, enhanced internal clocks, longer life andreprogrammable onboard processors to evolve with future needs.
"All in all, the 2F is improvedperformance, better anti-jam and it's got additional civil signals to helpaviation," said Brown.
Choreographing the GPS 2F-1 satellitepreparations at the Cape is the 45th Launch Support Squadron, a team of 75 peoplemaking certain that a healthy spacecraft gets to orbit safely.
"Traditionally, out of the entirelifetime of the satellite, the year leading up to and including launching thesatellite is by far the highest risk area," said Capt. Matt Hale, the squadron'sGPS section chief.
"We fall into the 45th Launch Group. TheLaunch Group is tasked with providing mission assurance capabilities back toSMC, the Space and Missile Systems Center, in L.A. They have program officersthat oversee the factories for the satellites and the factories for therockets. After they go through their development, they ship them down here andour job is to ensure the final integration activities that happen at the launchsite occur correctly."
The satellite was flown to Florida inside aC-17 airlifter on February 11 from Boeing'smanufacturing facility in El Segundo, California. After arriving at the SkidStrip, it was taken to Area 59 were GPS spacecraft undergo their pre-flightpreps.
Hale said the work readying the GPS 2F-1satellite was divided into two phases: an extensive testing period and then theusual launch campaign of activities.
"We have what we call a functional test.We do a test in L.A. before we leave the factory that goes through the wholefunctions of the spacecraft that ensures we have a baseline. When we bring itover to the Cape, we do another set of that test to ensure during transport allof the characteristics stayed the same. Transport is a very stressfulenvironment for a spacecraft, second only to launch," Hale said.
Engineers then performed an end-to-endcombined systems test between the user equipment that will acquire thenavigation signals from the satellite once it gets into space, as well aschecking the connectivity from the satellite to the ground control hub thatoperates the spacecraft in orbit.
"We verified the vehicle in terms of theperformance and signal characteristics, made sure the user segments wouldactually lock up and acquire the signal, and verified that the control systemhad controllability of the satellite," Brown said.
"We've had very few issues with thevehicle's performance. It's really operated well."
The earlier generations of GPS satellitesthat launched from the Cape — Blocks 2, 2A and 2R — went through Area 59before reaching Complex 17 where the Delta 2 rockets blasted off. In advance ofthe 2F era, the satellite accommodations were upgraded with modifications thatincluded stricter cleanliness, security changes, a larger door at entrance ofthe main bay and installation of a more-precise crane.
"Most of the existing capabilities werethere. It was just improving the current capabilities to tailor it to thespacecraft a little more," Hale said.
Area 59 features two large buildings whereGPS 2F-1 has traveled through during the past couple of months en route to thelaunch pad, Hale said.
"We have the NAVSTAR ProcessingFacility, the NPF, that's where the testing is done and the very first portionof processing is done. Then we move over to the DPF, the DSCS ProcessingFacility, that's where we do our major processing of the satellite."
But unlike the previous generations that rodeon smaller rockets, the GPS 2F craft will be delivered into orbit atop theDelta 4 and Atlas 5 fleets of boosters in the Air Force's Evolved ExpendableLaunch Vehicle program. That presents a major change in the way the satellitesare launched and affords the ground team a streamlined, if not simpler, task ofgetting the satellites in flight-ready condition.
The Delta 2 rockets, although highlyreliable, weren't powerful enough to inject the GPS satellites directly intothe orbiting constellation. The three-stage vehicles released the craft into ahighly elliptical orbit stretching from 100 miles at its closest point withEarth to some 11,000 miles at its highest point, which is the altitude wherethe GPS network resides. The newly-launched satellites were themselves fittedwith a solid-fuel kick motor that ignited a few days into flight and finishedthe job of propelling the craft into a circular orbit.
United Launch Alliance's powerful Delta 4 andAtlas 5 rockets will haul the GPS 2F satellites directly to their desireddestinations, bypassing the circuitous route of the past. So instead of takingdays to reach the GPS orbit, the new 2F-1 satellite will get there inthree-and-a-half hours on launch night.
And without having to deal with that kickstage, the Cape team's work is vastly simplified because it doesn't have putthe satellites through stringent spin-balancing and attaching the motor.
What's more, the two-piece shroud that servesas the rocket's nose cone will be brought into the cleanroom and placed aroundthe satellite instead of doing that work at the pad like Delta 2 did. Theencapsulated GPS 2F-1 payload will be driven to the pad already buttoned up tolaunch.
Before the satellite meets the Delta 4, thepast few weeks have involved installing the batteries, loading the maneuveringpropellant, working with the adapter hardware needed to mount GPS 2F-1 onto therocket and putting the final touches on the separation system that will releasethe craft from the launcher.
"It's all tedious work that has to bedone with precision," Brown said.
Departure from the cleanroom hangar istargeted for next week, when a motorized trailer carries the 3,400-poundsatellite up the road to Complex 37. It will be hoisted into the pad tower andbolted atop the rocket's second stage. Interface testing will follow to makesure the electrical connections are good. A rehearsal of the satellite'scountdown sequence is planned, too.
Boeing is slated to build a dozen Block 2Fsatellites to replace the current orbiting birds as they age, keeping thenavigation signals going strong for years to come.
"The importance is sometimes assumed,but it is worth noting. There are both military and civil applications for GPS.It is a very critical national asset in both regards. From the militaryperspective, it's pretty easy to envision that. We use it to obtain precisionnavigation and timing," said Hale.
"I think sometimes what people don'tunderstand are the civil applications. One that I like to highlight that a lotof people don't realize is the global economy is completely underpinned by thetiming signals that the GPS constellation provides. So all bank-to-banktransactions or your ATM transactions have a GPS time tag on them that allowsour economy to operate."
The Air Force could launch the GPS 2F-2satellite as early as November using an Atlas5 rocket from Complex 41.
"Sustainment is the primary purpose ofour launches. We have a constellation of satellites in orbit, so we aresustaining the existing constellation and incrementally bringing newcapabilities on orbit. So the impact having a single 2F on orbit with the 2F-1you might not see directly a day after the launch, but what you will see is GPS2F launches will incrementally improve the capabilities to meet thewarfighters' needs of tomorrow," Hale said.
"There is a lot of importance attachedto the GPS constellation and it's ability to be accurate and be available atall times. So our efforts here are in support in that critical national andworldwide asset."