New RL10C engine debuts on classified NROL-35 launch
After an early scrub was called due to multiple weather violations on Thursday, Dec. 11, NROL-35 was carried into the black on Friday, Dec. 12, for its secret mission for the National Reconnaissance Office at 7:19 p.m. PST (0319 GMT). It launched from Space Launch Complex 3 at Vandenberg Air Force Base in California, despite just a 30 percent chance of favorable weather conditions as the launch time approached. It was delayed a mere 5 minutes from the time expected for Friday’s launch.
Very little about the payload of NROL-35 is public knowledge, except that its purpose is “support of national defense,” according to United Launch Alliance (ULA ), whose rocket was the vehicle for the classified mission. However, satellite-watching enthusiasts like to make educated guesses based on what small amount of information is available, and the prevailing theory is that the payload is the next generation of the Trumpet and Trumpet F/O electronic intelligence (ELINT ) satellites. The guess is based on details like the long and bulbous payload fairing, the inclination of the launch and the extra-powerful rocket that was used to launch it.
The mission and capabilities of the original Trumpet satellites are still classified, though the program began in the 1990s, and little can be said for certain. It is known, however, that those satellites operate in a highly-elliptical Molniya orbit, which is an ideal orbit for monitoring high-latitude areas of Earth like Russia, and that they were “designed to monitor Soviet communications and missile tests” with “a large deployable mesh antenna,” according to NASA’s National Space Science Data Center.
Of course, the fact that this was the payload for NROL-35 remains unverified speculation, as the NRO is unlikely to confirm any correct guesses.
The mission patch for this NRO event achieved notoriety as they often do, though this time it was not for helping to fuel speculation about the payload, as often occurs, but merely for the striking nature of the graphic. The NROL-35 patch features a purple-haired woman in a black-and-purple dress with a white-eyed face-forward glare. In one hand she holds a trident in one hand, and in the other, what appears to be a ball of fire. The fireball has a tail of flame that either originates from the trident or crosses over to wrap around the trident. In the background is a simple star-filled sky, as if she represents the satellite itself.
Tonight, the secret payload was carried aboard a ULA Atlas V 541 booster, which has a five-meter payload fairing, four Aerojet Rocketdyne solid rocket boosters and one rocket engine on the Centaur upper stage. Atlas rockets have been launching from Vandenberg for about 50 years, but this is the first time the California base has seen this configuration of it. In fact, it is the most powerful configuration of the Atlas yet launched from the west coast. In the Atlas family it stands second only to the 551 configuration in terms of power, which has five solid rocket boosters.
This launch was also the debut of the RL10C to power the Centaur upper stage. It’s the newest generation of the RL10 engines built by Aerojet Rocketdyne, which have a long history of reliability. In June of 2013, it passed its final flight qualification, and ULA plans to use it as the standard upper-stage engine for future launches of both the Atlas V and Delta 4. The one exception is the two-engine version of the Centaur, as two RL10C engines cannot fit side-by-side as that configuration would require. Until now, the RL10A-2 has been used on the Atlas while the Delta employed the RL10B-2. The new variation was built with aspects of each of the previous engines.
“These are the days in your career that you really cherish,” said Aerojet Rocketdyne’s Program Manager for the RL10C-1 Program Michael Popp. “Seeing the culmination of the team’s efforts to develop and qualify this configuration for use on the Atlas Centaur is very rewarding. I know the team takes a lot of pride in the RL10C-1 engine and we look forward to delivering affordable upper-stage propulsion for many years to come.”
ULA has also been planning a complete new upper stage design concept, the Advanced Common Evolved Stage (ACES), which ideally will cost less, be more effective and have a longer lifetime in space than the Centaur and the Delta Cryogenic Second Stage. But, that may be put on hold due to increased pressure to replace the Russian RD-180 engine, which is used in the Atlas V first stage, with something American-made. The RD-180, made by NRO Energomash, has been the center of controversy since SpaceX requested an injunction against ULA over the use of the Russian engines while the crisis in Crimea was ongoing.
A representative of Aerojet Rocketdyne stated during the post-launch broadcast that the RL10C “brings the best combination of our assets, our capability and our performance, and delivers that to our customers.” He added that newer manufacturing techniques are very important to their recent efforts to develop the engines, including the “introduction of additive manufacturing for the RL10 components.”
“ULA is extremely pleased with this first flight of the new, RL10C-1 engine,” said Jim Sponnick, ULA Vice President for the Atlas and Delta programs. “We have been working closely with Aerojet Rocketdyne and our Air Force customers for several years to develop and extensively test this next-generation engine to enable the most reliable and cost-effective upper stage propulsion for our Atlas and Delta programs.”
For the launch itself, there were concerns about multiple possible weather violations, with a 70 percent chance of weather postponing the launch. Yet during the 20-minute built-in hold and about 10 minutes prior to the scheduled liftoff time, the weather officer declared the conditions “green” for the launch, against the odds. After that, 27 engineers and managers were polled during the launch status check (also called the “no/no-go poll”) to ensure all systems were operational, and it was declared “go for launch.”
A couple of minutes later, the terminal count was allowed to resume at T-4 minutes.
Three minutes before liftoff, the rocket’s tanks were brought to flight pressure. A minute after that, the vehicle was switched to internal power, as planned. At T-1 minute, the range was checked and was declared green — as opposed to a couple of recent launches, no boats were in the restricted zone.
Less than three seconds before launch the NRO Energomash RD-180 engine roared to life. Moments later, the Atlas V rocket lifted off the pad, flying into and beyond the clouds.
Just about one minute later, the rocket and its payload endured what is called “max-q,” or maximum dynamic pressure. This is the point of passage through Earth’s atmosphere at which the highest amount of aerodynamic stress is placed on the launch vehicle due to the high velocity and the pressure of the atmosphere. For this event, the RD-180 engine was throttled back slightly to reduce the stress on the rocket. Once the Atlas V passed safely through max-q, the RD-180 was throttled back up to full capacity.
Once the purpose of the solid rocket boosters was exhausted, they were jettisoned — first one pair at 1 minute and 48 seconds after liftoff, and then the other two a second and a half later.
Three minutes and 23 seconds into the flight, the five-meter fairing was jettisoned, as planned, and coverage of the launch ended as NROL-35’s secret payload was unsheathed.
Not much was heard from the NRO after launch, as expected. Jeff Orschel, public affairs officer with the NRO, only said, “We think it’s important for the American public to understand our mission…so we will be spreading the message via social media.”
This was ULA’s 91st launch since they formed in 2006, and their 14th and final launch for 2014. Additionally, it was the third and final mission for NRO this year, after NROL-33 in May and NROL-67 in April. For Aerojet Rocketdyne, this was the 455th RL10 engine to fly in space.
Only one more launch is planned from American soil for 2014, the Commercial Resupply Services 5 (CRS-5) launch aboard a SpaceX Falcon 9 rocket. The mission is now set for no earlier than Dec. 19, and its purpose is to carry supplies and experiments to the International Space Station under NASA’s Commercial Resupply Services contract. Besides this launch, there are also several Russian rockets scheduled to launch before year’s end.
Rae Botsford End is a freelance writer and editor whose primary work currently is writing technical white papers, contributing to SFI, and working on a speculative fiction novel that she hopes to have published soon. Rae wanted an opportunity to report on the various space-related events in and around Florida's Space Coast and approached SFI's founder about the possibility. Rae now covers an array of subjects for our growing website.