Almost five months since it last flew, United Launch Alliance (ULA) successfully closed-out a gap in missions on Thursday, 8 August, when its Atlas V 551 heavylifter roared aloft from Space Launch Complex (SLC)-41 at Cape Canaveral Air Force Station, Fla., laden with the latest Advanced Extremely High Frequency (AEHF-5) military communications satellite, bound for geostationary orbit. The 551—numerically designated to identify a 17.7-foot-diameter (5-meter) payload fairing, five strap-on, solid-fueled rockets and a single-engine Centaur upper stage—took flight at 6:13 a.m. EDT.
Coming 145 days since the last ULA launch, back in March, this represents the longest span between two missions in the 13-year history of the Centennial, Colo.-based launch provider. It is ULA’s third flight of 2019 and the 80th launch by a member of the Atlas V fleet.
This morning’s mission soundly eclipses the 122 days which elapsed between the OA-7 Cygnus in April 2017 and the long-delayed campaign to launch NASA’s most recent Tracking and Data Relay Satellite (TDRS-M) the following August. At the start of 2019, ULA’s manifest looked quite different, with up to eight launches planned to phase-out the expensive Delta IV Medium capability, one flight by the mammoth Delta IV Heavy and as many as five Atlas Vs, including unpiloted and crewed missions by Boeing’s CST-100 Starliner spacecraft for the Commercial Crew Program. However, the unpiloted Starliner slipped from April to September and it remains to be seen if the other launches—the sixth Orbital Test Vehicle (OTV-6) mini-shuttle, the STP-3 mixed payload for the Space Test Program and the first humans to ride an Atlas since Gordon Cooper in May 1963—can be achieved before year’s end. If eight flights are flown, this will tie with ULA’s launch tempo from 2018 and 2017.
“We have been steadily modifying our launch facilities in Cape Canaveral to facilitate Atlas and Vulcan launches and to modernize our infrastructure”, noted a ULA spokesperson in comments to AmericaSpace. “Modifications underway include upgrading the Vertical Integration Facility (VIF) platforms to accommodate all Atlas and Vulcan Centaur configurations and modifications to SLC-41 to accommodate Vulcan processing and launch. During this period, our teams have been conducting detailed reviews of our processes and procedures, and making appropriate updates. We have also added additional in-person training to ensure our personnel will be prepared to execute the remainder of the manifest.
Aboard today’s mission was AEHF-5, which joins its four cousins in providing fast and secure communications to link civilian leaders with military assets, anywhere in the world. Preparations entered high gear back on 13 April, when ULA’s Mariner cargo vessel departed the Decatur, Ala., facility, laden with the ten-story-tall Common Core Booster (CCB), which forms the central component of the Atlas V first stage, and the Centaur upper stage. Eight days later, on Easter Sunday, the Mariner reached Port Canaveral and the two stages were offloaded, bound initially for separate destinations: the CCB headed for the Atlas Spaceflight Operations Center (ASOC) for preparation ahead of vertical stacking and the Centaur commenced integration with its inter-stage adapter and the lowermost portion of the bulbous Payload Fairing (PLF). By mid-May, the CBC was hoisted atop the Mobile Launch Platform (MLP) in the Vertical Integration Facility (VIF), a quarter-mile (400 meters) from the SLC-41 pad surface. The five solid-fueled rocket boosters were attached to the base of the stack and the Centaur upper stage was mated in early June.
Meanwhile, the 13,600-pound (6,170 kg) AEHF-5 satellite was delivered from prime contractor Lockheed Martin’s facility in Sunnyvale, Calif., to the Cape, in early May for processing and encapsulation within its bulbous fairing. The payload was then transported over to the VIF and on 15 June was stacked atop the Atlas V by means of a heavy-duty overhead crane. Originally scheduled to launch on 27 June, the mission was delayed until the second week of July, due to a battery failure in the vehicle, before succumbing to a lengthier postponement until early August, following the discovery of “an anomaly during component testing at a supplier which has created a cross-over concern”.
“These were two distinct issues. The component is a common piece used in the upper stage of both the Atlas V and Delta IV vehicles”, noted the ULA spokesperson. After an anomaly occurred during component testing at a supplier, the team identified the root cause of the failure and determined that some minor rework was required to the hardware. To ensure 100% mission success, ULA determined it was necessary to remove and replace the components on all upper stages in process.”
At length, on 25 July ULA formally confirmed a revised launch date of 8 August, with a two-hour “window” extending from 5:44 a.m. through 7:44 a.m. EDT.
Four AEHF satellites were successfully launched by ULA between August 2010 and last October, forming the core of a network which will provide fast and secure communications to connect civilian leaders with military assets around the world. Intended to replace the outdated Milstar network, AEHF operates at extremely high frequencies (44 GHz uplink) and super-high frequencies (20 GHz downlink) and can relay communications directly, without the need to pass through ground stations.
The satellites’ phased-array antennas help to eliminate potential sources of radio jamming and each AEHF can support data rates as high as 8.192 Mbits/sec. The AEHF birds also feature advanced encryption, low probability of interception and detection and the ability to penetrate the electromagnetic interferences caused by nuclear weapons to route communications, real-time video, maps and targeting data to users on land, at sea or in the air.
As well as marking the 80th launch by a member of the Atlas V fleet since August 2002, this morning’s mission was also the tenth voyage of the 551, whose Russian-built RD-180 engine at the CCB base and five solid-fueled motors generate a liftoff thrust in excess of 2.6 million pounds (1.1 million kg). It is expected that the 551 will fly again later in 2019 to loft the STP-3 payload for the Air Force’s Space Test Program. That mission will also see it trial the new Graphite Epoxy Motor (GEM0)-63 strap-on booster configuration, which boasts higher overall performance and a reduced operational cost when compared to the currently-in-service GEM-60.
Ignition of the CCB took place at T-2.7 seconds and the RD-180 quickly ramped up to full power, before the five strap-on boosters flared with their characteristic staccato crackle at T-0 and the Atlas V 551 was airborne. Shortly after clearing SLC-41, the rapidly-ascending rocket commenced a pitch, roll and yaw program maneuver to establish itself onto the proper trajectory to deliver AEHF-5 to orbit.
Forty-eight seconds into the climb, it passed smoothly through maximum aerodynamic turbulence and by 125 seconds the five boosters, exhausted of their solid fuel, had been jettisoned. The RD-180 continued to burn for a further 2.5 minutes, before shutting down. The CCB was discarded and left the Centaur to pick up the baton and conduct a series of three intricate burns to carry AEHF-5 to its desired orbital slot.
“We are proud of the tremendous efforts by the combined ULA, Lockheed Martin, Aerospace and government team in making this launch such a success,” said Mr. Don Ruffin, USAF Space and Missile Systems Center (SMC’s) Strategic SATCOM division chief. “The satellite is healthy and operating as expected. We have now turned our attention to maneuvering it into its final orbital location over the next several months and look forward to many years of service in providing critical communications capabilities to our warfighters around the world.”
Looking ahead, the final Delta IV Medium booster—already delayed a month past its targeted 25 July launch date—is expected to fly no sooner than 22 August, carrying a Block III Global Positioning System (GPS) satellite to Medium Earth Orbit (MEO). And in the weeks to come, ULA and the Atlas V will make history and offer a backward nod to history, by launching crew-capable vehicles for the first time in more than five decades. Not since the final Project Mercury voyage of legendary astronaut Gordon Cooper in May 1963 has a member of the Atlas booster family been entrusted with a human cargo. That will change in the late summer and fall, with the first unpiloted test flight of Boeing’s CST-100 Starliner on 17 September and its first crewed mission before year’s end.
“In preparation for a busy 2020 manifest, our Decatur factory will set a record-setting manufacturing pace with 30 boosters in production during 2019 and 2020″, ULA added in their comments to AmericaSpace. “This includes both complete Atlas and Delta boosters. Vulcan qualification and first flight hardware is currently being fabricated. At the end of July, the first Vulcan Centaur booster was sent for structural qualification testing.”