NASA plans second Megarocket ‘Hotfire’ test after unexpected shutdown

NASA’s recent next-gen megarocket hotfire test was supposed to go eight minutes, but it lasted only 67 seconds. The space agency has an explanation for the premature shutdown, saying everything is fine, but a second test remains a distinct possibility.

The first Space Launch System (SLS) hotfire test, carried out on Saturday, Jan. 16 at NASA’s Stennis Space Center in Mississippi, stopped at just over un-minute mark when a key parameter has entered out of range territory, Explain NASA in a press release. The parameter in question has to do with the hydraulics required for the gimbal, or pivoting, of each rocket motor.

For the test – the eighth and (possibly) the last in the Green Run test program – NASA planned to fire the rocket’s four RS-25 engines for eight minutes. With the 212 feet tall (65-metre) the rocket stage anchored at the B-2 test stand, and with the center stage filled with over 700,000 gallons of propellant, the engines kicked in at 5:27 p.m. EST, spewing out a gigantic cloud of exhaust. It lasted exactly 67.2 seconds until the computers shut it down.

NASA reviewed the data and performed preliminary inspections of the system, finding that the rocket hardware is in “excellent condition” and that the shutdown “was triggered by intentionally conservative test settings to ensure the safety of the central stage during the test. “

Built by Boeing, SLS will be NASA’s most powerful rocket and a key component of upcoming Artemis missions to the Moon. It consists of a main stage with four RS-25 engines, as well as two small solid rocket boosters attached to either side of the space shuttle. Once operational, SLS be used to send American astronauts to the Moon at some point in the 2020s. An unmounted inaugural launch could take place later this year.

Speaking to SpaceFlightNow, outgoing NASA chief Jim Bridenstine said NASA “may be able to bring the rocket back to Kennedy [Space Center in Florida] and get it ready for launch, ”adding that this“ decision has not been made ”as the situation remains uncertain.

Indeed, NASA is still trying to determine whether a seconda fire test will be required. Based on the results of the first test, the team might change the thrust vector control settings to avoid a similar shutdown.down, according to NASA.

The preprogrammed parameters for the hotfire test are ground test specific and are designed so that the center stage thrust vector control system can safely adjust the orientation of the RS-25 engines. In addition to thrust vector control system, a series of actuators provide the forces necessary to card each motor, and they are powered by multiple Auxiliary Power Units (CAPUs) in the center stage. The gimbalof the engines were operating as expected, but the associated hydraulic system “exceeded the predefined test limits that had been established” resulting indown, according to NASA.

NASA says that’s not a problem, and had SLS been in flight, the rocket would have continued its journey using the remaining CAPUs. And in fact, NASA said the shortened test demonstrated this in action.

In addition, the gimbalThe test that shut down the CAPU was a “case of intentional stress to the system that was intended to exercise the capabilities of the system,” NASA said. “The data is evaluated as part of the process of finalizing predefined test limits before the next use of the main step.”

In terms of positives, this was the second successful wet test (i.e. the rocket was fully loaded with propellant), the team was able to pressurize the propellant tanks, and they performed a countdown to ignition of the engines. At full throttle, the engines reached their maximum capacity at 1.6 million pounds of thrust.

The team will continue to investigate the apparent lightning observed around the engines. The thermal blankets used to protect the engine from the intense heat showed signs of burns, which is not strange given their proximity to the engines and the CAPU exhaust. Still, NASA wants to be sure that this was normal behavior.

As noted, a second hotfire test is not out of the question. As reported in SpaceFlightNow, John Shannon, head of the SLS program at Boeing, said the team wanted to acquire and evaluate at least 250 seconds of data during the test before moving on to the next step. Oobviously, a full eight-minute test would be even better, as that is the total time it will take the SLS rocket to reach space.

Yes, this would present a potential delay, but there may be no more rush. It’s not clear if the Biden administration will require NASA to reach the lunar surface in 2024, an accelerationtimetable pushed by the Trump administration.