ULA to launch WGS-9 comsat to continue updating defense communications
CAPE CANAVERAL, Fla. — After a delay of more than one week, United Launch Alliance (ULA) is preparing to launch the ninth planned Wideband Global SATCOM (WGS-9) spacecraft aboard a Delta IV Medium+ (5,4) from Cape Canaveral Air Force Station’s Space Launch Complex (SLC) 37 on March 18, 2017; the launch window is 7:44–8:59 p.m. EDT. The WGS-9 satellite, together with the WGS-8 spacecraft that launched on December 7, 2016, will increase warfighters’ communication capacity by 45 percent.
The WGS constellation is able to support broadcast, multicast, and point-to-point communications. It is also the only military satellite communications system that can support simultaneous X-band and Ka-band communications. The system shares data in real time for tactical communications and supports a wide variety of missions, from search and rescue efforts to military operations.
The WGS system includes eight steerable/shapeable X-band beams formed by separate transmit/receive phased arrays, 10 Ka-band beams served by independently steerable diplexed antennas, and one transmit/receive X-band Earth-coverage beam. WGS can tailor coverage areas and connect X-band and Ka-band users anywhere within its field-of-view. The X-band phased array antenna enables the satellite to avoid jamming without sacrificing performance.
WGS has been deployed in two series, with WGS-1 through -3 being Block I, and the rest of the series being Block II. Block II satellites feature a radio frequency bypass capability designed to support airborne intelligence, surveillance, and reconnaissance platforms that require ultra-high bandwidth and data rates demanded by unmanned aerial vehicles. WGS-9 is the third Block II follow-on satellite.
While Block I and II satellites can instantaneously filter and downlink up to 4.410 GHz, WGS-9 can filter and downlink up to 8.088 GHz of bandwidth. Depending on the mix of ground terminals, data rates, and the modulation and coding schemes used, a single WGS satellite can support data transmission rates of over 6 gigabits per second (Gbps), and WGS-9 may support over 11 Gbps.
The WGS-9 satellite is built on the Boeing 702HP spacecraft bus. The 702HP architecture was announced by Boeing in 1998, and it has been the basis of many subsequent public and private satellites. The launch date for the last satellite in the constellation, WGS-10, has not yet been announced.
Some of the end users of WGS-9 include the Australian Defence Force, U.S. Army, U.S. Navy ships and submarines, national command authorities for the nuclear forces, and various national security / allied national forces. As a result, this mission is being funded through an international partnership consisting of the U.S. Air Force, Canada, Denmark, the Netherlands, Luxembourg, and New Zealand.
On March 4, the launch date for WGS-9 was changed to March 14 after the ULA team discovered an issue with the Delta IV first stage booster during standard prelaunch inspections. This additional time allows the ULA team to ensure all systems are operating nominally prior to launch.
This will be the seventh launch of the Delta IV Medium+ (5,4) configuration, which includes a five-meter-diameter payload fairing and four solid rocket boosters used during the first-stage liftoff. The 5,4 configuration first flew in 2009. To date, the 5,4 has been used to launch only WGS satellites.
Video Courtesy of United Launch Alliance
Bart Leahy is a freelance technical writer living in Orlando, Florida. Leahy's diverse career has included work for The Walt Disney Company, NASA, the Department of Defense, Nissan, a number of commercial space companies, small businesses, nonprofits, as well as the Science Cheerleaders.