A critical test on Saturday of the four main engines propelling the first phase of NASA’s giant space launch lunar rocket is the last major obstacle to the costly, often delayed launch of the booster late this year on a non-flying test flight.
The refurbished Aerojet Rocketdyne RS-25 engines are screwed on top of the massive B-2 test post at NASA’s Stennis Space Center in Mississippi, and they are scheduled for a full eight minutes from approximately 5:00 PM EST, same time duration needed for an actual flight. .
Including shuttle flights and ground tests after the shuttle, RS-25 engines have been turned on more than 3,000 times so far and have been shot for more than 18,000 minutes, but never four at a time and never with a rocket the size of the SLS not. The aim is to test the performance of the stage as a whole under flight conditions.
NASA
“This will be our first test to fire all four RS-25 engines simultaneously in this new Space Launch System setup,” said Jeff Zotti, Program Director of Aerojet Rocketdyne RS-25. “We are all looking forward to seeing the nuclear phase of the world’s most powerful rocket launch for the first time.”
The SLS flight version features two 17-story Northrop Grumman solid-fuel amplifiers, each delivering 3.6 million pounds of thrust; the four RS-25s, which together produce 1.6 million pounds of pressure; a second phase powered by hydrogen; An Orion crew capsule and an emergency escape system.
The rocket will weigh 5.75 million pounds, be 322 feet long and generate 8.8 million pounds of thrust upon lifting, making it the most powerful operational rocket in the world and the most powerful American rocket ever built. Even more powerful variants are being planned by NASA for its Artemis lunar program, which raises the push to a staggering £ 9.5 million.
For the so-called ‘green run’ on Saturday, the Boeing-powered SLS rocket’s 212-foot-long, 27.6-foot-wide first phase will be tested as a fully operational booster, loaded with 537,000 liters of liquid hydrogen and 196,000 liters of liquid oxygen for a planned test fire of 485 seconds.
If the stage is closed consistently on the test standard, new latest engine computers will push the main engines up to 95%, about a minute into the test. They will do the same during an actual flight to reduce stress on the rocket as it passes through the area of maximum aerodynamic pressure.
The 7,775-pound engines, which previously helped launch 21 shuttles, will also move hydraulically or at specific times to commanded positions to verify their ability to steer the rocket precisely while climbing into space, both early in flight and later in the ascent.
The engine nozzles have new insulation to protect them from the heat they will eventually experience from the nearby 5,000-degree solid rocket exhaust plumes.
NASA
During the ground shake test, sensors will monitor other voltage and voltage, temperature, fuel flow rate, pressure and a variety of other parameters to make sure the rocket is ready for the first Artemis lunar mission late this year.
Equally important, the test will verify the performance of the rocket’s complex flight computer system and software, along with flight management and pre-flight safety systems.
“The test is scheduled for 485 seconds,” said Julie Bassler, SLS core manager of NASA’s Marshall Space Flight Center in Huntsville, Alabama. “The stage is equipped with more than 1,400 sensors, including pressure, temperature, accelerometers and strain gauges.”
“With this hot fire, there is a lot of data, including how aviation and software management and control will perform with the integrated core stage and engine propulsion system,” Bassler said, adding: “This green-running test is up to this core phase for the first time. So this is a big milestone for us. “
Boeing SLS program manager John Shannon, a former aircraft director of the spacecraft: “This is the vehicle with the largest instrument we will ever be able to fly. So we get a tremendous amount of engineering data.”
Assuming the green run test goes well and no major problems are encountered, NASA executives hope to send the SLS stage to the Kennedy Space Center by February.
Once there, the stage will be attached to two solid fuel improvers is currently mounted on a mobile launching platform in the cave vehicle assembly building, or ‘stacked’. The already completed top stage will be mounted on top of the core and the rocket will be supplemented by a Lockheed Martin Orion crew capsule and the emergency escape system.
The composite rocket and launch platform are then towed by a powerful crawler tractor to road 39B and prepared for flight. Unlike SpaceX rockets and others that are being developed, the SLS is not reusable and the first phase charger and its engines will be destroyed when they fall back into the atmosphere after climbing into space.
NASA hopes to launch the rocket late this year on its first flight and send the unexamined Orion capsule on a 40,000-mile flight 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 administration schedule calling for the first flying SLS Orion flight – Artemis 2 – in 2023, followed by a lunar landing using the third SLS rocket by the end of 2024.
But according to the schedule, money is accepted to develop a new lunar lander. The program has not yet received the necessary budget of Congress, and it is not yet known what support the Biden government will provide.
The SLS team, in turn, is optimistic that the first Artemis rocket will be ready for launch before the end of the year.
“This powerful rocket is going to enable us to be ready to support the agency and the country’s deep space mission to the moon and beyond,” said John Honeycutt, NASA SLS Program Manager at Marshall.
But it was a rocky road.
The development program is much more than budget and at least two years behind schedule. NASA’s inspector general reported last March that total SLS program costs were expected to rise to more than $ 18 billion by the time the Artemis 1 rocket finally rises.
The delays and high costs have given rise to debate over the need for the SLS to transport astronauts to the moon, given the availability of less powerful but much cheaper SpaceX Falcon Heavy rockets and other heavy-life boosters now being developed. But NASA executives say the SLS is, in the short term, the only rocket capable of accommodating the Orion crew capsule and other major components for the Artemis program.