A critical test that fires on Saturday the four main engines driving the first stage of the lunar rocket of NASA’s space launch system is the main obstacle before the costly and often delayed launch of the fully assembled booster later this year in a unmanned test flight.
Stuck in place on the massive B-2 test bench at NASA’s Stennis Space Center in Mississippi, the upgraded Aerojet Rocketdyne RS-25 engines are scheduled to fire for eight minutes starting at 5 p.m. EST, the same duration required for an actual flight.
Including shuttle flights and post-shuttle ground tests, RS-25 engines have been fired more than 3,000 times to date and fired for more than 18,000 minutes, but never four at a time and never with a rocket the size of of the SLS. The goal is to test the performance of the stage as a whole in flight conditions.
NASA
“This will be our first test firing all four RS-25 engines simultaneously in this new space launch system configuration,” said Jeff Zotti, director of the Aerojet Rocketdyne RS-25 program. “We are all looking forward to seeing for the first time the central stage of the world’s most powerful rocket.”
The flight version of the SLS will include two 17-story Northrop Grumman solid fuel reinforcements, which will generate 3.6 million pounds of momentum; the four RS-25s, which generate 1.6 million pounds combined pulls; a second stage powered by hydrogen; an Orion crew capsule and an emergency escape system.
The rocket will weigh 5.75 million pounds, have a height of 322 feet and generate 8.8 million pounds of takeoff momentum, making it the most powerful operational rocket in the world and the American rocket. most powerful ever built. NASA is planning even more powerful variants for its Artemis moon program, which makes the takeoff boost reach a staggering 9.5 million pounds.
For Saturday’s so-called “green run,” the first stage of the 212-foot-tall, 27.6-foot-wide SLS-operated SLS rocket will be tested as a fully operational booster, loaded with 537,000 gallons. of liquid hydrogen and 196,000 gallons of liquid oxygen for a 485-second test schedule.
With the stage locked on the test bench, the new state-of-the-art engine computers will accelerate the main engines up to 95%, about a minute on the test. They will do the same during a real flight to reduce the stresses of the rocket when it crosses the region of maximum aerodynamic pressure.
The 7,775-pound engines, which previously helped propel 21 shuttle launches, will also run on hydraulic gimbal or move to commanded positions at certain times, to verify their ability to steer the rocket accurately during space ascent, both at the beginning of the flight as after the ascent.
The engine nozzles feature new insulation to protect them from the heat they will experience with nearby 5,000-degree solid rocket exhaust feathers.
NASA
Throughout the ground agitation test, sensors will monitor other voltages and voltages, temperatures, fuel flows, pressures and various other parameters to ensure the rocket is ready for launch on the first Artemis moon mission at the end. of this year.
Equally important, the test will verify the performance of the complex flight computer system and rocket software along with pre-flight safety and propellant management systems.
“The test is scheduled for 485 seconds,” said Julie Bassler, SLS’s principal stage director at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “The stage is equipped with more than 1,400 sensors that include pressure, temperature, accelerometers and manometers.”
“With this hot fire, there is a lot of data, including the command and control functions of avionics and software with the integrated core phase and engine propulsion system,” said Bassler, who added: this central stage . So this is a huge milestone for us. “
John Shannon, a former space shuttle flight director, said the Boeing SLS program manager said, “This is the vehicle with the most instruments we will fly. So we will get a lot of engineering data.”
Assuming the ecological performance test works well and no major problems occur, NASA officials expect to send the SLS stage by barge to the Kennedy Space Center in February.
Once there, the stage will adhere two solid fuel boosters it is currently being assembled or “stacked” on a mobile launch pad in the cavernous vehicle assembly building. The upper stage, now complete, will be mounted on the core and the rocket will be topped by a Lockheed Martin Orion crew capsule and its emergency escape system.
The mounted rocket and its launch pad will be dragged to the 39B platform by a powerful transport of chains and ready for flight. Unlike SpaceX and others under development, the SLS cannot be reused and the first-stage booster and its engines will be destroyed when they fall back into the atmosphere after ascending into space.
NASA expects to launch the rocket on its first flight later this year, sending the unmanned Orion capsule to a flight 40,000 kilometers beyond the moon and back. What happens next will largely depend on how the Biden administration prioritizes space.
NASA
NASA is currently working on a Trump administrative schedule that requires the first SLS-Orion piloted flight (Artemis 2) in 2023, followed by a landing on the moon with the third SLS rocket in late 2024.
But this schedule involves funding to develop a new lunar. The program has has not yet received the required budget of Congress, and it is not yet known what level of support the Biden administration will provide.
For its part, the SLS team is optimistic that the first Artemis rocket will be ready for launch before the end of the year.
“This powerful rocket will put us in a position to be prepared to support the country’s agency and space mission to the Moon and beyond,” said John Honeycutt, NASA’s SLS program manager at Marshall.
But it has been a rocky road.
He development program far exceeds the budget and at least two years late. The NASA inspector general reported last March that the total costs of the SLS program were expected to exceed $ 18 billion by the time the Artemis 1 rocket finally took off.
Delays and high costs have sparked debate about the need for the SLS to transport astronauts to the moon, given the availability of less powerful but much less expensive SpaceX Falcon Heavy rockets and other heavy-lifting propellers that are now in development. . But NASA officials say the SLS is the only short-range rocket available that is capable of accommodating the Orion crew capsule and other important components planned for the Artemis program.