Astrobotic’s Peregrine lunar lander failed to achieve the moon due to an issue with a single valve within the propulsion system, in accordance with a report on the mission launched Tuesday. Firm management stated in a press convention that engineers have redesigned the valve and launched extra redundancy into the propulsion system of its subsequent lander, Griffin, to make sure the issue doesn’t reoccur.
The report comes from a evaluate board assembled shortly after the Peregrine mission concluded in January. That mission encountered bother simply hours after launch on January 8, when engineers activated the spacecraft’s propulsion system for the primary time on orbit.
At that time, the gasoline and oxidizer tanks ought to’ve been pressurized with helium, upon the opening of two strain management valves, or PCVs. However helium started to movement “uncontrollably” by means of the second valve into the oxidizer tank, Astrobotic CEO John Thornton defined throughout the press convention.
“That caused a significant and rapid over-pressurization of the tank,” he stated. “Unfortunately, the tank then ruptured and subsequently leaked oxidizer for the remainder of the mission.”
That PCV was unable to reseal, possible as a result of a mechanical failure brought on by “vibration-induced relaxation” between some threaded parts contained in the valve, the evaluate board’s chair John Horack stated. Telemetry knowledge was in a position to pinpoint the placement and timing of the anomaly, and this knowledge was according to the autonomous sequence to open and shut the PCV, and the place of the valve on the propulsion system. Engineers have been additionally in a position to replicate the failure in floor testing.
Whereas the oxidizer leak continued, Astrobotic’s crew was in a position to stabilize the spacecraft, cost its batteries, and energy its payloads. However the problem was in the end deadly to the mission, and after 10.5 days, the spacecraft returned to Earth and burned up within the ambiance.
The 34-person evaluate board included 26 folks inner to the corporate and eight from exterior. The board reviewed not simply the information collected throughout the mission, but in addition all the information from the flight qualification marketing campaign and element testing. Ultimately, it decided that the possible reason for the malfunction was the failure of that single helium PCV within the propulsion system.
The board additionally compiled a timeline of occasions that led to the failure, and it begins all the best way again in 2019, when Astrobotic contracted an unnamed vendor for the event of the propulsion feed system. When that vendor began struggling technical and provide chain points as a result of COVID-19 pandemic, Astrobotic made the choice in early 2022 to terminate their contract and end the partly assembled feed system in-house.
“By this time, we’d already made the decision to do Griffin’s propulsion system in-house, to do more vertical integration,” Astrobotic’s mission director Sharad Bhaskaran stated. “We’d already developed a lot of the capabilities to do that propulsion integration. … This also burned down some of the risk going into the Griffin program, which is far more complex than Peregrine.”
However Astrobotic engineers began encountering points with the unique vendor’s propulsion parts — particularly the PCVs. In August 2022, they switched to a special, unnamed PCV provider, and people valves have been put in on the lander.
A closing set of assessments on the propulsion system confirmed leaks in one of many two PCVs — however not the one which in the end leaked on orbit. That one examined superb; the one which leaked was repaired. Whereas Bhaskaran acknowledged that the second PCV was recognized “as a risk in our risk register” as a result of leak with the primary throughout testing, engineers in the end deemed that the failure was low as a result of the lander handed closing acceptance testing.
He justified not changing the second PCV, saying it was situated a lot farther into the spacecraft and would have required “extensive surgery” on the lander, invalidated the ultimate testing, and carried extra danger that comes with disassembly and reassembly.
Horack echoed that the crew’s decision-making was sound all through: “I really found that, in looking at the team and looking at what happened … I can’t see any decisions that were made in the flow leading up to the launch where I would have said, ‘Hey, I think you should have done this differently.’”
These findings have already began to tell the event of the a lot bigger Griffin lander, which is presently scheduled to launch to the moon earlier than the top of 2025. Along with redesigning the valve, engineers have launched a regulator within the propulsion system to regulate the movement of helium to the gasoline and oxidizer tanks, and backup latch valves as added redundancy in case the difficulty reoccurs with a PCV.
