Only weeks after passing its 10th anniversary of operations, and just over a year since its 100th mission, United Launch Alliance (ULA) has triumphantly concluded its 12th and final flight of 2016. The Centennial, Colo.-based launch services provider successfully launched its workhorse Atlas V booster—flying for the 60th time as a ULA vehicle and its 68th mission in total—from Space Launch Complex (SLC)-41 at Cape Canaveral Air Force Station, Fla., at 2:13 p.m. EST Sunday, 18 December. Primary payload for the mission was EchoStar-XIX, the largest and most capable high-speed broadband internet communications satellite yet placed into orbit. Within 32 minutes of liftoff, the 13,900-pound (6,300-kg) payload had been delivered into a looping elliptical orbit, from where it will be maneuvered over the next several days to a circular Geostationary Earth Orbit (GEO). Poignantly, ULA’s coverage of today’s launch ended with a tribute to the late Mercury astronaut John Glenn, who flew aboard an Atlas in February 1962 and who died earlier this month.
As detailed in AmericaSpace’s EchoStar-XIX preview article, this mission has come about in a surprisingly short period of time. In August 2015, Lockheed Martin Commercial Launch Services (LMCLS) was selected to provide the launch services, via the ULA Atlas V, reportedly due to EchoStar Corp.’s need to been on-orbit by the fall of 2016. Early last month, EchoStar-XIX—which has been fabricated by Space Systems/Loral (SS/L), on the framework of its highly reliable SSL-1300 satellite “bus”—was flown cross-country from Palo Alto, Calif., to the Kennedy Space Center (KSC) in Florida, aboard an Antonov heavy airlifter. It was uncrated and proceeded through several weeks of checkout and fueling, before being integrated with the Atlas V last week.
After encapsulation within its hand-painted 4-meter (13-foot) Extra-Extended Payload Fairing (XEPF), EchoStar-XIX was transported to the Vertical Integration Facility (VIF) at the SLC-41 site and installed atop the Atlas V. A standard Launch Readiness Review (LRR) was concluded on Friday and the 194-foot-tall (59-meter) stack was rolled approximately a quarter-mile (400 meters) from the VIF to the SLC-41 pad surface on Saturday. Upon achieving a status of “hard-down” on the pad, the booster was centered and propellant umbilicals and electrical and data connections were established. The track mobiles from the Mobile Launch Platform (MLP) were removed and, early Sunday, flight control systems were initiated, ground command, control and communications instrumentation was brought online, and interfaces between the Atlas and the Launch Control Center (LCC) were verified.
Loading of propellants got underway with highly refined rocket-grade kerosene (known as “RP-1”), which provides the fuel for the Russian-built RD-180 engine of the Atlas V’s first stage. ULA CEO Tory Bruno tweeted on Saturday that the RP-1 had been satisfactorily loaded into the first-stage tanks. In the meantime, launch teams pressed ahead with final preparations, with a 70-percent probability of acceptable weather conditions at T-0 on Sunday afternoon. According to the 45th Weather Squadron at Patrick Air Force Base, increasing moisture and warm southerly winds were expected to trigger “an isolated shower threat mid-to-late afternoon” in advance of a cold front moving toward the Carolinas. Although it was predicted that a “slight threat” of thunderstorms existed later on Sunday afternoon, the key concerns were a potential violation of the Cumulus Cloud Rule and Thick Cloud Rule.
With the storable RP-1 fuel aboard the vehicle, the process got underway to load cryogenic oxygen and hydrogen aboard the Centaur upper stage, as well as liquid oxygen aboard the first stage. When complete, the first stage—also known as the Common Core Booster (CCB)—contained around 626,000 pounds (284,000 kg) of propellant, with the Centaur holding almost 46,300 pounds (21,000 kg). Tracking an on-time launch at 1:27 p.m. EST, the countdown entered its final built-in hold at 12:53 p.m., at which point the clock was held at the T-4 minute mark for what was expected to be 30 minutes of final checks.
Shortly before the expected emergence from the hold, ULA Launch Conductor Dillon Rice performed a “Go/No-Go” poll of his 28-member launch team, producing a unanimous string of “Go” calls and a “Green Board” for liftoff at the start of the window at 1:27 p.m. As the terminal countdown progressed, the Atlas V’s fuel and oxidizer tanks were secured at flight levels, but a “Hold” was called at T-74 seconds. As the unidentified issue was worked, a string of new T-0 times were released: firstly 1:47 p.m., then 1:52 p.m., and ultimately 2:13 p.m. Finally, ULA CEO Tory Bruno tweeted: “Issue isolated. Working on resolution.” During this period, the EchoStar-XIX payload was removed from internal power and placed back onto Ground Support Equipment (GSE) power. By the turn of the hour, it seemed that the glitch was well on the way to being resolved. “Issue is understood,” tweeted Mr. Bruno at 1:57 p.m. “Bird is good. Plan identified. Working through the details.”
At length, EchoStar-XIX was returned to internal power, running off its on-board batteries, at 2:07 p.m. The ULA team continued to manually monitor the criteria which had triggered the hold and a second “Go/No-Go” poll was executed by Mr. Rice, allowing the clock to emerge again from the hold at T-4 minutes at 2:09 p.m. During the second terminal countdown of the afternoon, the Atlas V transitioned to internal power and at T-20 seconds the igniters aboard the three strap-on solid-fueled boosters were armed. The boosters can only be configured in a handful of locations around the base of the CCB—due to the MLP design—and the 431 vehicle flew with two solids on the “north” side of the stack and a single solid on the opposite side.
At T-2.7 seconds, the Russian-built RD-180 engine roared to life, quickly ramping up to 860,000 pounds (390,000 kg) of thrust from its twin nozzles. At zero, the three solids ignited with a staccato crackle, punching out around 1.14 million pounds (515,000 kg). Five seconds into the flight, the avionics aboard the Centaur upper stage commanded a pitch, roll, and yaw program maneuver, establishing the Atlas V onto the proper azimuth for injection into orbit. Passing Mach 1 at 45 seconds, and experiencing maximum aerodynamic pressure (“Max Q”) on its airframe at 58 seconds, the solids expired around two minutes into the mission.
All three were jettisoned and the RD-180 continued to burn for another two minutes, ahead of its own shutdown at four minutes and 27 seconds. In the moments before Booster Engine Cutoff (BECO), the powerful engine was burning propellant at a rate of 1,506 pounds (683 kg) per second, by which time the Atlas V and its payload were traveling in excess of 12,000 mph (19,300 km/h) at an altitude of 78 miles (125 km) and a downrange distance of 275 miles (442 km) from the Cape. Shortly after BECO, the first stage was jettisoned and the restartable RL-10C-1 engine of the Centaur upper stage was ignited.
This first Centaur burn ran for almost nine minutes, during which time the XEPF payload fairing was jettisoned, exposing EchoStar-XIX to the space environment for the first time. By this point, the stack weighed just six percent of what it did at T-0. Following the first Centaur Main Engine Cutoff (MECO), the combo coasted for almost ten minutes, ahead of the second “burn,” which lasted a little less than six minutes. EchoStar-XIX was deployed from the Centaur at 2:45 p.m., some 32 minutes into the mission, to begin its first steps on a mission which is expected to run for up to 15 years. The satellite’s initial Geostationary Transfer Orbit (GTO) carried a perigee of 126 miles (204 km) and an apogee of more than 40,000 miles (65,000 km), well beyond the nominal 22,000 miles (35,000 km) Geostationary altitude. The satellite’s on-board propulsion system will be used over the coming days and weeks to raise the perigee and lower the apogee to achieve a near-circular Geostationary Earth Orbit (GEO).
Today’s mission wraps up a highly successful year for ULA, which has seen the company launch eight Atlas Vs and four Delta IVs from both Cape Canaveral and Vandenberg Air Force Base, Calif. These flights have transported seven military reconnaissance, surveillance, communications, and navigation payloads into orbit, together with the WorldView-4 commercial Earth-imaging satellite, the latest Geostationary Operational Environmental Satellite (GOES-R), and a single Cygnus cargo mission, bound for the International Space Station (ISS). Additionally, the Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) sample return mission was launched in September, headed for the carbonaceous asteroid Bennu.
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