March 14, 2022 - When NASA’s Space Launch System (SLS) lifts off for the first time in the coming months, it will be continuing an Aerojet Rocketdyne legacy in human spaceflight that dates back to the very beginning of the space age.
Although there will be no crew aboard this inaugural flight of the super-heavy lift exploration rocket—whose first and second stages are powered by Aerojet Rocketdyne engines—subsequent SLS missions will take astronauts farther into space than ever before as part of NASA’s Artemis program.
Aerojet Rocketdyne propulsion is prominently featured on multiple hardware elements of Artemis, just as it was in the Apollo program, and throughout the nation’s human spaceflight history. The company’s enablement of space exploration began, of course, with Project Mercury.
NASA’s Project Mercury, initiated in 1958 in the wake of the Soviet Union’s historic Sputnik 1 launch the year before, was America’s first human spaceflight program. Mercury leveraged two rockets, both adapted from missiles: the Redstone for suborbital missions, including Alan Shepard’s May 5, 1961 flight that made him the first American to reach space; and the Atlas for orbital flights. The Mercury-Redstone-3 that carried Shepard’s Freedom 7 capsule to space was a single-stage vehicle powered by a specially modified version of Aerojet Rocketdyne’s legacy engine A7 liquid-fueled engine that generated 83,000 pounds of thrust.
Less than one year after Shepard’s historic flight, John Glenn launched atop an Atlas LV-3B rocket to become the first American to orbit the Earth. The Atlas LV-3B was a stage-and-a-half vehicle with Aerojet Rocketdyne’s MA-5 engine.
Project Mercury was followed by Project Gemini, which used the Titan II rocket (also a converted long-range missile) to launch 10 pairs of U.S. astronauts to orbit in 1965 and 1966. The Titan II GLV, or Gemini-Titan, was a two-stage vehicle with both stages powered by Aerojet Rocketdyne-legacy engines. Additionally, legacy companies developed and supplied thrusters that controlled the Gemini spacecraft’s movements in orbit.
The first-stage was powered by the LR87-7, which really consisted of two engines combined into a single system. Adapted to the needs of the Gemini program, the LR87-7 was powered by a combination of nitrogen tetroxide and a form of hydrazine, called Aerozine 50, and generated about 430,000 pounds of thrust at sea level. Notably, the LR-87 was the only engine whose different variants burned the three most commonly used propellants: hydrazine, hydrogen and kerosene.
Aerojet Rocketdyne’s Aerozine 50-fueled LR91 powered the Titan II second stage. The engine, earlier versions of which were fueled by kerosene, generated about 100,000 pounds of thrust.
The Apollo program made extensive use of Aerojet Rocketdyne-legacy propulsion systems. Perhaps most famous of these is the massive F-1 engine that powered the first stage of the most powerful rocket of them all – the Saturn V. The F-1 remains today the most powerful single-combustion-chamber, liquid-fueled rocket engine ever built.
Archive photo of the manufacturing line for the thrust chamber of the mighty F-1 rocket engine – the most powerful single-combustion-chamber, liquid-fueled rocket engine ever built. Five F-1 engines, each generating 1.5 million pounds of thrust, were used to launch the Saturn V rocket. Click the image to enlarge.
Before the Saturn V ever flew, there were two smaller predecessors, one of which was the Saturn IB that carried astronaut crews. The first Saturn variant, Saturn I, never carried crews but did carry an Apollo spacecraft and also is notable as an early application of Aerojet Rocketdyne’s RL10 engine, six of which powered the vehicle’s second stage. Variants of the RL10 remain in use on rocket upper stages today.
Like its predecessor, the Saturn IB (also known as the uprated Saturn I) featured eight Aerojet Rocketdyne-built H-1 engines fueled by liquid oxygen and kerosene. On the newer vehicle, these engines generated a combined 1.6 million pounds of thrust, roughly equivalent to a single F-1. The second stage of the Saturn IB featured Aerojet Rocketdyne’s J-2, a liquid oxygen and hydrogen-fueled engine generating 200,000 pounds of thrust that went on to power the second stage of the much larger Saturn V. The Saturn IB made its first crewed launch in October 1968 on the Apollo 7 mission, and was later used on four crewed missions: three to NASA’s Skylab space station in 1973, and one that docked with a Soviet Soyuz capsule in 1975.
The giant Saturn V rocket, which ultimately launched six NASA astronaut crews to the lunar surface, was a three-stage vehicle powered entirely by Aerojet Rocketdyne propulsion systems. The first stage used five F-1 engines generating a whopping 7.9 million pounds of combined thrust. The second stage featured five J-2 engines delivering more than one million pounds of thrust combined, while the third stage used a single J-2. In addition, multiple smaller Aerojet Rocketdyne engines performed second- and third-stage propellant settling burns.
Aerojet Rocketdyne’s Apollo contributions did not end with the rocket. The Apollo command and service module (CSM) propelled itself into and out of lunar orbit using Aerojet Rocketdyne’s AJ10-137 engine. The CSM propulsion system also performed the crucial lunar deorbit burn that enabled the crew capsule to safely return to Earth, as well as course corrections between the Earth and Moon.
Aerojet Rocketdyne also provided a critical component, the injector system, as well as overall integration for the Apollo lunar module ascent engine, which lifted astronauts off the surface of the Moon for rendezvous with the orbiting CSM. The Apollo Lunar Excursion Module, as well as the CSM, also used numerous Aerojet Rocketdyne-legacy reaction control system thrusters.
In the wake of the Apollo program, NASA moved to a reusable space transportation system capable of supporting crews on orbit for more than two weeks. Three Space Shuttle Main Engines (SSME), built by Aerojet Rocketdyne, helped power the space shuttle to orbit. After each flight, the engines were removed and refurbished. Upgraded versions of these engines, referred to now as RS-25 engines, will power the first stage of the SLS.
Once in space, the space shuttle relied on the Orbital Maneuvering System (OMS), powered by a two AJ10 variant engines, for orbit insertion, maneuvering and re-entry. The space shuttle orbiter contained two OMS pods, each powered by a single AJ10-190 generating 6,000 pounds of thrust, with one on either side of the vertical stabilizer at the vehicle’s aft end. Aerojet Rocketdyne also supplied the propellant tanks for the OMS engines, as well as numerous smaller Aerojet Rocketdyne-legacy reaction control thrusters for orientation.
International Space Station
In addition to its role on the space shuttle, which did most of the heavy lifting in assembling the space station, Aerojet Rocketdyne supplied and helps maintain the outpost’s power system.
Aerojet Rocketdyne also provides propulsion for Boeing’s CST-100 Starliner crew transport vehicle. Starliner launches atop the United Launch Alliance Atlas V rocket, which is human-rated to fly with two RL10 upper-stage engines and two AJ-60A solid rocket boosters.
The Starliner itself is full of Aerojet Rocketdyne propulsion, including 20 engines on the service module to support orbital maneuvers as well as attitude control in the event of a low-altitude launch abort. The service module also has 28 reaction control engines for orbital maneuvering and attitude control. On the crew module, 12 Aerojet Rocketdyne thrusters provide orientation for atmospheric re-entry. Finally, the service module has four launch abort engines that would whisk the astronaut capsule away from the rocket in the event of a launch or ascent anomaly.
Aerojet Rocketdyne propulsion figures prominently in three major Artemis flight systems: the SLS super-heavy lift launch vehicle, the Orion crew spacecraft and the deep space Gateway.
Space Launch System: Four RS-25 engines, the follow-on to the SSME, each generating 512,000 pounds of thrust, power the SLS core stage. The SLS second stage initially will feature a single RL10 engine, with later versions using four RL10s, dramatically increasing the rocket’s capability.
Orion: NASA’s Orion crew spacecraft, which launches atop the SLS, also relies heavily on Aerojet Rocketdyne propulsion. Orion’s European Service Module uses an AJ10 variant to maneuver the crew module. As backup, there are eight, 110-pound-thrust auxiliary engines, which also provide in-orbit trajectory corrections and positioning. The crew module will position itself for and during atmospheric re-entry using 12 Aerojet Rocketdyne reaction control system engines, each generating 160 pounds of thrust. On Orion’s launch abort system, Aerojet Rocketdyne provides the jettison motor, which generates 40,000 pounds of thrust to separate the crew capsule from the launch abort system (LAS). During nominal flights, this engine is used to separate the LAS from the spacecraft following ignition of the SLS second stage.
Aerojet Rocketdyne’s Orion contributions are not limited to propulsion. Once the spacecraft splashes down in the ocean, it will be stabilized in the water by five helium-filled flotation devices. The helium is stored in composite overwrapped pressure vessels supplied by Aerojet Rocketdyne’s ARDÉ subsidiary.
Gateway: Finally, the Gateway, a platform in cislunar space that will be used to stage landings and provide communications and other support functions, will feature three Aerojet Rocketdyne Advanced Electric Propulsion System thrusters. These state-of-the-art thrusters will maneuver the Gateway to different orbital altitudes above the Moon, and could serve as the basis for future systems supporting missions to other destinations, such as Mars.
Such a role surely will be but one of many for Aerojet Rocketdyne in humankind’s next great exploration adventure.