Major core stage hardware completed for first SLS flight
NASA has completed major work for all five parts of the core stage for the first flight of the massive Space Launch System (SLS). Additionally, manufacturing has been completed for all four core stage test articles with evaluation underway on the engine section structural test article at the Marshall Space Flight Center in Huntsville, Alabama.
Announced in a Sept. 28, 2017, news release, NASA finished major welding on the liquid hydrogen tank that will be used for the first flight of the SLS, Exploration Mission-1, scheduled for no earlier than late 2019 with an uncrewed Orion capsule. All five structures—the liquid hydrogen tank, liquid oxygen tank, the engine section, intertank and forward skirt—will be joined to form the 212-foot (65-meter) tall core stage. The hydrogen tank alone comprises nearly two-thirds of the stage.
“The big items are done, and the team is focused on the intricate details of outfitting the flight hardware to perform specific tasks for the most powerful rocket in the world,” Chad Bryant, the SLS core stage manufacturing lead at Marshall, said in the news release. “When assembled, the core stage will stand taller than a 20-story building and include hundreds of cables for everything from data collection to propulsion systems.”
The three sections of the core stage that will require the most work inside are the engine section, where four RS-25 engines will be housed, along with the intertank and forward skirt, which hold most of the avionics. After that, engineers will apply thermal protection insulation to maintain cryogenic propellant as cold as minus 423 degrees Fahrenheit (minus 253 degrees Celsius). This insulation will be added to the outside of the stage and in critical places inside the rocket.
“Think about this work like building a car,” said Bryant. “We have the main structure or frame built. Now, we are installing the guts and electronics that turn the rocket into a transportation system: propulsion systems in the engine section, computer and other electronics in the forward skirt and the intertank.”
The two largest core stage structures were built and welded at the Vertical Assembly Center at NASA’s Michoud Assembly Facility in New Orleans. The liquid oxygen tank is currently undergoing hydrostatic testing, which requires the tank to be filled with 200,000 gallons (7.6 million liters) of water to experience similar pressures of flight.
“This is the first time we are doing this test for an SLS tank, and it’s a major milestone,” Ben Birkenstock, SLS stages manufacturing engineer at Marshall, said in the news release. “We’ve covered the tank with sensors, and we’ll collect data to show the tank welds hold up when it is loaded with water that simulates propellant.”
The pathfinder arrives at Michoud
Meanwhile, the SLS core stage pathfinder arrived at Michoud on Sept. 27 where the team will use it to test critical operations including assembly, transporting the stage on NASA’s barge Pegasus to Stennis Space Center in Bay St. Louis, Mississippi, and lifting it onto the B-2 test stand where production cores will be hot-fired for pre-launch testing called “the green run.”
“NASA did not want to do complex operations for the first time with a one-of-a-kind piece of flight hardware,” Tim Flores, manager for stages ground support equipment, said in the news release. “The SLS core stage pathfinder will allow us to practice all these critical maneuvers with a dimensional replica of the core stage that is the same size, shape and weight as the valuable flight hardware.”
The pathfinder stage was built and assembled at G&G Steel in Cordova, Alabama. Dynetics Corporation of Huntsville, Alabama, is expected to completed final outfitting of the stage and turn it over to the space agency in early October.
Heather Smith's fascination for space exploration – started at the tender age of twelve while she was on a sixth-grade field trip in Kenner, Louisiana, walking through a mock-up of the International Space Station and seeing the “space potty” (her terminology has progressed considerably since that time) – she realized at this point that her future lay in the stars. Smith has come to realize that very few people have noticed how much spaceflight technology has improved their lives. She has since dedicated herself to correcting this problem. Inspired by such classic literature as Anne Frank’s Diary, she has honed her writing skills and has signed on as The Spaceflight Group’s coordinator for the organization’s social media efforts.