Air Force AEHF-4 Satellite Arrives in Florida for October Atlas V Launch

Lockheed Martin’s fourth AEHF satellite in processing before being shipped to Cape Canaveral for launch atop a ULA Atlas V rocket in October for the U.S. Air Force. Two other AEHF satellites are in production as well. Photo Credit: Lockheed Martin

The U.S. Air Force’s fourth Advanced Extremely High Frequency (AEHF-4) satellite, which will become part of a constellation to replace the outdated Milstar network in providing fast and secure communications to link U.S. and allied civilian leaders with warfighters and military assets, anywhere in the world, has arrived at Cape Canaveral for launch as soon as early October.

Built by Lockheed Martin, the 13,000+ pound spacecraft was shipped from their Sunnyvale, California facility to Florida’s Space Coast on July 27 aboard a U.S. Air Force C-5 transport aircraft, following a successful battery of tests and realistic simulations of its future launch experience to ensure it will arrive on orbit functionally sound and ready to operate through the extreme temperature changes of space.

Now at its launch site, the satellite will undergo final launch checkouts, propellant loading and preparations for flight atop the largest and most powerful of ULA’s Atlas V fleet, the rarely used powerhouse Atlas V ‘551’ rocket, as soon as early October.

ULA Atlas V launch of the U.S. Air Force’s third Advanced Extremely High Frequency (AEHF-3) satellite into orbit. Photo Credit: John Studwell / AmericaSpace

The ‘551’ variant of the Atlas V boasts a 17-foot-wide (5-meter) payload fairing, five strap-on solid-fueled rockets and a single-engine Centaur upper stage. First used in January 2006 to loft NASA’s New Horizons spacecraft to Pluto, the 551 has since seen service to deliver NASA’s Juno spacecraft to Jupiter in August 2011 and five heavyweight Mobile User Objective System (MUOS) military communications satellites for the U.S. NAVY between February 2012 and June 2016. It also launched the AFSPC-11 mission to orbit for the U.S. Air Force earlier this year.

The satellites operate at extreme high frequencies (44 GHz uplink) and super-high frequencies (20 GHz downlink), and can relay communications directly without passing through ground stations. Their phased array antennas help to eliminate possible sources of radio jamming, and each AEHF spacecraft can support data rates as high as 8.192 Mbits/sec.

A single AEHF satellite provides greater total capacity than the entire legacy five-satellite Milstar.

AEHF-1 was launched in August 2010, followed by AEHF-2 in May 2012 and AEHF-3 in September 2013.

Launch of AEHF-4 was moved to October of this year after a power regulator issue was discovered.

“With government concurrence, we established both hardware and operational courses of action to mitigate the issue, and we’re pleased to see this delivery take place,” said a Lockheed spokesperson.

AEHF satellites will form a constellation that will provide U.S. military forces with far-greater communications capabilities. Image Credit: Lockheed-Martin

“Four AEHF satellites in orbit means protected global connectivity for those who need it most, from the president to deployed soldiers,” said Michael Cacheiro, Lockheed Martin vice president of Protected Communications. “We offer powerful end-to-end systems so that more operational users can have assured connectivity in contested environments. Delivering this fourth satellite in orbit will be critical to the Air Force, as it will connect all four satellites on orbit, forming a geostationary ring to provide uninterrupted global communications.”

Once on orbit, AEHF-4 will, “complete the minimum constellation of AEHF satellites needed to bring global Extended Data Rate (XDR) connectivity to warfighters and international partners,” says Lockheed.

“XDR adds an unprecedented protected communication capability, providing 10 times more communications throughput than the legacy MILSTAR constellation,” stated Cacheiro.

The satellite enables military communications with real-time video, battlefield maps and targeting data, boosted by a five-fold increase in individual user data rates.

Canada, the Netherlands and the United Kingdom all use the AEHF satellites as well.

AEHF-4 (foreground) with the antenna wings extended and AEHF-5 (background) visible in the open DELTA chamber for thermal testing. Photo: Lockheed Martin

Lockheed is under contract to deliver a total of six AEHF satellites to the U.S. Air Force, and the Mission Control Segment. And while AEHF-4 nears launch, AEHF-5 is currently in system-level testing in Sunnyvale, and is expected to follow AEHF-4 with launch from the Cape in mid-2019.

And while no launch date is set yet for AEHF-6, Lockheed says it’s development is progressing on schedule.

The AEHF team is led by the U.S. Air Force Military Satellite Communications Systems Directorate at the Space and Missile Systems Center, Los Angeles Air Force Base, Calif. Lockheed Martin Space, Sunnyvale, Calif., is the AEHF prime contractor and system manager, with Northrop Grumman Aerospace Systems, Redondo Beach, Calif., as the satellite payload provider.



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