Update: The four engines fired for 67.7 seconds, then shut down due to an issue (all public information points to an engine issue right now.) This is far short of the 8.5 minutes required, and...
Update: The four engines fired for 67.7 seconds, then shut down due to an issue (all public information points to an engine issue right now.) This is far short of the 8.5 minutes required, and short of the 250 seconds apparently required under Boeing's contract with NASA. This will almost definitely result in another hot fire test, and further increases the chances that the first SLS launch slips into 2022.
NASA is currently (as of this comment) at T-40 minutes to the scheduled ignition time for the "Green Run Hot Fire Test", an 8.5-minute test firing of an SLS first stage core. If all goes well during the test, this SLS core will fly as soon as the end of this year (but more likely sometime next year.)
I've linked to the NSF forum livestream, because there's far more technical commentary than NASA's official stream.
Latest on what caused the premature shutdown: NASA blames moon rocket engine shutdown on hydraulic system software And a tweet from Wayne Hale (former Space Shuttle Program Manager) highlighted in...
(all public information points to an engine issue right now.)
Software in place to monitor hydraulic systems during a test firing of NASA's Space Launch System moon rocket was to blame for an early engine shutdown Saturday, not an actual problem with the booster's shuttle-heritage engines or its complex propulsion system, NASA said Tuesday.
All four of the Aerojet Rocketdyne RS-25 engines operated normally throughout the test and while an instrumentation glitch with engine No. 4 was called out near the end of the run, it was unrelated to the shutdown. NASA said the huge rocket was not damaged and otherwise performed normally.
"During gimballing, the hydraulic system associated with the core stage's power unit for engine 2, also known as engine E2056, exceeded the pre-set test limits that had been established," NASA said. "As they were programmed to do, the flight computers automatically ended the test.
"The specific logic that stopped the test is unique to the ground test when the core stage is mounted in the B-2 test stand at Stennis. If this scenario occurred during a flight, the rocket would have continued to fly using the remaining CAPUs to power the thrust vector control systems for the engines."
The blog post said the rocket successfully transferred power to a redundant hydraulic system before the shutdown, adding that the engine gimbal test "was an intentionally stressing case for the system that was intended to exercise the capabilities of the system."
"The data is being assessed as part of the process of finalizing the pre-set test limits prior to the next usage of the core stage," the post said.
Observers initially heard a call on the control room audio channel referring to an "MCF," or major component failure, on engine No. 4 just before the shutdown. That led observers so suspect engine No. 4 caused the abort.
But NASA says the MCF call was the result of an instrumentation glitch unrelated to the shutdown and that the control system still had "sufficient redundancy to ensure safe engine operation during the test." Engineers expect to resolve the issue before the next use of the stage.
And a tweet from Wayne Hale (former Space Shuttle Program Manager) highlighted in the article is worth pointing out too:
Getting some more data on last weekend’s SLS hotfire test. Limits were set to conservatively protect hardware and cut the test off early. No damage to core stage or engines. My advice would be to retest and get complete data - may be a couple of weeks but schedule is secondary.
— Wayne Hale (@waynehale) January 19, 2021
Update: The four engines fired for 67.7 seconds, then shut down due to an issue (all public information points to an engine issue right now.) This is far short of the 8.5 minutes required, and short of the 250 seconds apparently required under Boeing's contract with NASA. This will almost definitely result in another hot fire test, and further increases the chances that the first SLS launch slips into 2022.
NASA is currently (as of this comment) at T-40 minutes to the scheduled ignition time for the "Green Run Hot Fire Test", an 8.5-minute test firing of an SLS first stage core. If all goes well during the test, this SLS core will fly as soon as the end of this year (but more likely sometime next year.)
I've linked to the NSF forum livestream, because there's far more technical commentary than NASA's official stream.
Latest on what caused the premature shutdown:
NASA blames moon rocket engine shutdown on hydraulic system software
And a tweet from Wayne Hale (former Space Shuttle Program Manager) highlighted in the article is worth pointing out too: