Test firing of NASA moon rocket sets stage for maiden flight
NASA and Boeing readied a gargantuan Space Launch System rocket for a second test firing in Mississippi Thursday to clear the way for a long-delayed maiden flight late this year or early next to kick off the space agency's Artemis moon program.
Two months after glitches cut short an initial attempt on January 16, the 21-story SLS core stage's four shuttle-heritage RS-25 main engines were expected to ignite one after the other, at 120 millisecond intervals, throttling up to a combined thrust of 1.6 million pounds. The two-hour test window opens at 3 p.m. EDT.
Firmly locked down on a massive test stand at NASA's Stennis Space Center just east of New Orleans, the core stage's Aerojet Rocketdyne engines were expected to fire for up to eight minutes — the duration of an actual climb out of the atmosphere — consuming more than 700,000 gallons of liquid oxygen and hydrogen in the process.
The test run called for throttling the engines down and back up as they will be during an actual flight, testing the rocket's thrust vector control, or steering, system and monitoring how propellant tank pressures are maintained as the fuel level drops.
Data from hundreds of sensors will reflect a wide variety of parameters, including critical vibration levels at different thrust settings. The data will feed into 10 "detailed verification objectives," or DVOs, required to demonstrate the rocket is ready for flight.
Mission managers said they expected to collect all the data needed in the first four minutes, but planned to let the engines run twice that long to simulate an actual climb to space and to monitor performance when the tanks are nearly empty and the rocket weighs a fraction of its initial 2.3 million pounds.
"This is not by any means a vanilla firing the core stage," said Boeing SLS manager John Shannon. "Since it's a highly instrumented vehicle, we're taking that opportunity to do some very aggressive maneuvers of the thrust vector control system. ... It's going to stress the vehicle.
