NASA is building the world’s most powerful rocket stage to take a new generation of astronauts to the moon. On Thursday, the agency plans to fire the engines.
The rocket, dubbed Space Launch System (SLS), is designed to eventually reach 365 feet (111 meters) in height. The system is part of NASA’s larger Artemis program, an approximately $ 30 billion effort to get humans to the lunar surface for the first time since 1972. NASA spent about $ 18 billion to develop the missile.
The 212-meter-high nuclear stage – the largest piece of the system and its structural backbone – is the world’s largest and most powerful rocket stage, according to NASA. It is currently clamped in a test rig at the Stennis Space Center in Mississippi, ready for what is known as a “hot fire” test on Thursday afternoon.
That means NASA will fire the engines continuously for about eight minutes – the time it takes to put a rocket and a spaceship into orbit. If the engines pass this test, the nuclear stage will be ready to join the rest of the rocket at the Kennedy Space Center in Florida.
Crews at Stennis Space Center will lift the core stage of NASA’s Space Launch System into place on January 22, 2020.
NASA
This hot fire is the eighth and final step in NASA’s Green Run program, which is designed to thoroughly test every part of the nuclear phase ahead of SLS’s first launch – an unmanned test flight around the moon called Artemis 1. could launch SLS in November.
The ultimate goal is to transport astronauts to the moon sometime in mid to late 2020.
An artistic representation of the Space Launch System rocket taking off from NASA’s Kennedy Space Center in Florida.
NASA / MSFC
“Our core-phase Green Run is the most comprehensive test we are conducting to ensure that SLS can safely launch Artemis missions to the moon,” said John Honeycutt, the SLS program manager, at a press conference in February. “This is a generational opportunity to learn as much as possible about the missile while we have it in this test configuration, before flying.”
Watch NASA rocket fire live
NASA TV kicks off at 3 p.m. ET on Thursday with a live broadcast of the test. That’s the beginning of the two-hour window that NASA carved in front of the hot fire. Watch the live stream here:
To prepare for the test, six bins will transport 733,000 liters of cryogenically cooled propellant to the test site on Thursday. Three of the bins will carry liquid hydrogen, while the other three will carry liquid oxygen. The core stage has a fuel tank for each. Once NASA gives the “go”, the ships will load the propellant into those tanks to prepare the rocket stage for fire.
The last attempt at hot fire broke itself off
Boeing is NASA’s prime contractor for the core phase, and Aerojet Rocketdyne is responsible for the four RS-25 engines, which were also used on NASA’s fleet of space shuttles.
NASA previously tried the same hot-fire test in January, but the engines suddenly stopped within a minute.
An SLS engine burns propellant (left) and then shuts down abruptly (right) during a hot fire test on January 16, 2021.
NASA TV
It turned out that a flight computer had automatically aborted the test because a system controlling the motions of the engines had exceeded the limits set by NASA prior to the hot fire. The limits were deliberately conservative, NASA said, because the agency doesn’t want to push the missile so hard that it gets damaged during testing.
But in the two months since, NASA adjusted the test parameters to be less conservative. The SLS team has found it can push the limits without much additional risk to the hardware, Honeycutt said. Had the system exceeded its earlier limits during an actual launch, NASA said, the missile would have continued to fly.
The team also fixed a liquid-oxygen valve that was not opening properly, a problem they discovered while preparing for the upcoming hot fire.
This time, the SLS program managers hope the engines will run for at least four minutes. While the full test should take eight minutes, four NASA would provide enough data to verify that the core stage is safe to fly.
If something goes wrong, NASA will have to redo the hot fire a third time, which could delay the first mission and disrupt the Artemis program’s ambitious timeline in general. The program aims to land the first woman and the next man on the moon by 2024.
“We’re still on track to have a chance to launch this year, but we also recognize that there are things to come, like the weather and COVID and some initial operations,” Tom Whitmeyer, who leads the NASA program. it is developing new reconnaissance systems such as SLS and Orion, according to the press conference. “So the plan is to launch this year, but we will continue to make progress throughout the year and we will be sure to let you know how we are doing.”