Pure beauty, and it’s GO! at last — United Launch Alliance and the U.S. Air Force Space Command’s Space and Missile Systems Center (USAF/SMC) achieved a launch of the WGS-2 mission, which marks the 15th Atlas V launch and the third launch of an Atlas V 421 configuration.
WGS-2 joins the service’s first WGS satellite, which also launched on an Atlas V October 10, 2007. A United Launch Alliance Atlas V rocket carrying the U.S. Air Force’s second Wideband Global SATCOM (WGS) satellite lifted off from Space Launch Complex-41 at Cape Canaveral Air Force Station, Florida, at 8:31 p.m. EDT April 3rd. After a 31-minute flight, WGS-2 was placed successfully in orbit where it will provide enhanced communication abilities to our troops in the field. (Photo by Pat Corkery, United Launch Alliance.)
The WGS-2 mission is the second installment of the Wideband Global SATCOM (WGS) system. The WGS satellites are an important element of a new high-capacity satellite communications system; providing enhanced communications capabilities to our troops in the field for the next decade and beyond. WGS enables more robust and flexible execution of Command and Control, Communications Computers, Intelligence, Surveillance, and Reconnaissance (C4ISR), as well as battle management and combat support information functions. WGS-2 augments the existing service available through the UHF F/O and WGS SV-1 satellites by providing additional information broadcast capabilities.
The launch began with RD-180 engine ignition approximately 2.7 seconds before liftoff (T-2.7 seconds). SRB ignition occurred at T+0.8 seconds. Liftoff occurred at T+1.1 seconds. Shortly after the vehicle cleared the pad, it performed its pitch/yaw/roll program. Maximum dynamic pressure occurred 66 seconds into flight. The SRBs burned out at T+90 seconds, and jettisoned at T+140 seconds. Booster engine cutoff (BECO) occurred at approximately 255 seconds. Telemetry data was gathered by TEL-4, Jonathan Dickinson Missile Tracking Annex (JDMTA), Antigua, Diego Garcia, and Guam Tracking Stations. The Tracking and Data Relay Satellite System (TDRSS) also participated in gathering telemetry during the WGS-2 mission.
Centaur separated 6 seconds after BECO. Centaur main engine start (MES1) occurred 10 seconds after the separation event. Payload fairing jettison took place at 8 seconds after MES1. At approximately 15 minutes into the mission, main engine cutoff 1 (MECO1) occurred and Centaur achieved its parking orbit. After a 9-minute coast phase, Centaur reoriented itself for MES2, which began approximately 24 minutes into the mission and lasted about 4.5 minutes. After MECO2, Centaur re-oriented its attitude for the separation event. The WGS-2 spacecraft separated about 31.5 minutes after launch. The turn to Centaur Collision and Contamination Avoidance Maneuver (CCAM) attitude began about three minutes after the separation event. Centaur’s mission ended 1.5 hours after launch after blowdown of the propellant tanks and burn off of residual N 2H4.
The WGS-2 spacecraft (SC) is an approximately 13,200-lb. communications satellite. The SC is mated to the Centaur upper stage by the space vehicle contractor (SVC)-provided spacecraft launch vehicle adapter (SCLVA), separation system, and electrical harness, and a ULA-provided, mission-unique C22 launch vehicle adapter (LVA). WGS supports communications links in the 500 MHz range of the X-band and 1 GHz range of the Ka-band spectra. WGS can filter and route up to 4.875 GHz of instantaneous bandwidth. Depending on the mix of ground terminals, data rates, and modulation schemes employed, a WGS satellite can support data transmission rates between 2.4 and 3.6 Gbps. WGS has 19 independent coverage areas that can be positioned throughout its field of view. This includes eight steerable/shapeable X-band beams formed by separate transmit/receive phased arrays; 10 Ka-band beams served by independently steerable diplexed antennas (three with selectable RF polarization); and transmit/receive X-band Earth-coverage beams. WGS can tailor coverage areas and connect X-band and Ka-band users anywhere within its field of view.
Four Army Wideband Satellite Operations Centers (WSOC) provide command and Control of WGS. Each Global SATCOM Configuration and Control Element (GSCCE) has the capability to control up to three satellites at a time, using X-band or Ka-band telemetry and command links. Spacecraft platform control is accomplished by the 3rd Space Operations Squadron (3 SOPS) at Schriever Air Force Base (AFB) in Colorado Springs, Colorado; using WGS mission-unique software and databases. Support technologies for WGS include the xenon-ion propulsion system (XIPS), which is 10 times more efficient than conventional bipropellant systems; highly efficient triple-junction gallium arsenide solar cells; and deployable radiators with flexible heat pipes. Four 25-cm XIPS thrusters remove orbit eccentricity during transfer orbit operations. The thrusters are also used to perform orbit maintenance and any required station-change maneuvers during the mission’s life. The triple-junction gallium arsenide solar cells provide on-orbit electrical power for the spacecraft. The deployable radiators’ flexible heat pipes provide increased radiator area; resulting in a cooler, more stable thermal environment for the spacecraft.
The WGS-2 payload consists of a single communications satellite. The two-burn, minimum-residual shutdown mission will fly an easterly trajectory from SLC-41 with an approximately 93° flight azimuth. The separation event will release the WGS-2 spacecraft into a supersynchronous transfer orbit with a 220.3-nmi perigee, an apogee radius no greater than 39,687 nmi, and an approximately 20.93° inclination. The launch video at the top above is courtesy of United Launch Alliance.
