NROL-61 marks sixth flight of 421 configuration of ULA Atlas V
CAPE CANAVERAL, Fla. — United Launch Alliance (ULA) successfully sent the sixth of the 421 configuration of the company’s Atlas V launch vehicle into the morning skies. The payload for this morning’s flight was a classified satellite for the National Reconnaissance Office (NRO).
This morning’s launch, designated NROL-61, got under way at 8:37 a.m. EDT (12:37 GMT) at the very start of the four-hour launch window. Using a Russian-built (by NPO Energomash) RD-180 rocket engine, the Atlas V 421 leaped off of the pad and, assisted via two AJ-60A Solid Rocket Motors, and cut a large arc across the morning skies, announcing itself to the surrounding wetlands.
The weather for today’s launch simply could not have been more perfect. The clear skies the Sunshine State produced easily confirmed predictions that weather would provide at least a 90 percent of favorable conditions for launch.
“Our team diligently prepared for this important mission through a series of rigorous rehearsals, readiness reviews and pre-operational checkouts,” said Wayne Monteith, 45th Space Wing commander and mission Launch Decision Authority. “This mission, once again, clearly demonstrates the successful collaboration we have with our mission partners at NRO, Space and Systems Missile Center and ULA as we continue to shape the future of America’s space operations. This successful launch helps to ensure that vital NRO resources will continue to bolster our national defense while showcasing why the 45th Space Wing is the ‘World’s Premiere Gateway to Space.’”
Two days earlier, at 9:05 a.m. EDT (13:05 GMT) July 26, 2016, the Atlas rocket was rolled from the protective confines of the Vertical Integration Facility (VIF) just across from Cape Canaveral Air Force Station’s Space Launch Complex 41 (SLC-41) in Florida.
On launch day, a few seconds after it had left the pad at SLC-41, the Atlas V began the pitch, yaw, and roll maneuver that was required to gain the proper ascent profile the launch vehicle and its precious cargo needed to reach orbit. This also helped decrease aerodynamic loads on the rocket.
Approximately 47 seconds after it had started its journey, the Atlas V 421 had reached Mach 1—the speed of sound. The booster reached the point in its flight where aerodynamic loads are at maximum (more commonly known as max-Q) about five seconds later.
At two minutes and nine seconds mission elapsed time, the two AJ-60A Solid Rocket Motors (SRMs), with their fuel spent, were jettisoned.
In the lead-up to Booster Engine Cutoff (BECO), the vehicle burned propellant at a rate of 1,672 pounds (758.4 kilograms) per second. At four minutes, 10 seconds after liftoff, traveling some 12,500 mph (20,100 km/h) at an altitude of 72 miles (116 kilometers) some 238 miles (383 kilometers) downrange, BECO occurred. The stage separated with the Centaur upper stage six seconds later.
About 10 seconds after booster separation, the Aerojet Rocketdyne Centaur RL-10C-1 engine ignited pushing the classified payload toward its spaceward destination. Not long after that, some four minutes and 34 seconds, the payload fairing separated. NROL-61 was shielded on its way out of Earth’s atmosphere by a four-meter fairing, by far the most commonly employed.
As was a classified mission for the NRO, the upper stage burned for an unknown amount of time to send the satellite into an undisclosed orbit.
“Thank you to the entire mission team for years of hard work and collaboration on today’s successful launch of NROL-61. We are proud the U.S. Air Force and NRO Office of Space Launch have entrusted ULA with delivering this critical asset for our nation’s security,” said Laura Maginnis, ULA vice president of Custom Services. “Our continued one launch at a time focus and exceptional teamwork make launches like today’s successful.”
The Atlas V family of rockets first took to the skies in 2002. They are launched from both SLC-41 as well as Launch Complex 3E at Vandenberg Air Force Base, located in California.
The rockets each carry a three-digit designation which provides specifics about the rocket’s components. The first number in the series describes the diameter of the payload fairing (this is always either a four or a five). The second details how many SRMs the rocket is employing, with the final denoting how many engines are in the Atlas V’s upper stage.
The Atlas V’s first stage is powered by a single dual-chamber kerolox-fueled RD-180 engine. The power plant produces 860,000 pounds (3,830 kilonewtons) of thrust at launch. Additionally, the twin boosters on this flight burned for 94 seconds, with each providing 379,600 pounds (1,688 kilonewtons) of thrust.
The Centaur upper stage sported a single RL10C-1 engine. It produces 25,000 pounds (110 kilonewtons) of thrust during the final phase of the flight. NROL-61 will mark the 13th time the C-1 variant of the RL10 has flown.
United Launch Alliance and the NRO have been long-time partners. The NROL-61 mission represents the 23rd NRO launch by ULA, and the 13th on an Atlas V, although it was the first launch on the 421 configuration for the intelligence agency. This was the third NRO launch, and ULA’s sixth, of 2016.
ULA’s next mission will be to launch the AFSPC-6 satellite atop a Delta IV rocket. Liftoff is slated for August 19 from SLC-37, two pads south of SLC-41.
Video courtesy of SpaceFlight Insider
Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology, Space.com, The Mars Society and Universe Today.