Astrobotic’s Peregrine lunar lander failed to achieve the moon due to an issue with a single valve within the propulsion system, in keeping with a report on the mission launched Tuesday. Firm management mentioned 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 hassle 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 gas and oxidizer tanks ought to’ve been pressurized with helium, upon the opening of two stress 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 in the course of the press convention.
“That prompted a major and fast over-pressurization of the tank,” he mentioned. “Sadly, the tank then ruptured and subsequently leaked oxidizer for the rest of the mission.”
That PCV was unable to reseal, doubtless as a result of a mechanical failure attributable to “vibration-induced leisure” between some threaded elements contained in the valve, the evaluate board’s chair John Horack mentioned. Telemetry knowledge was in a position to pinpoint the situation and timing of the anomaly, and this knowledge was in keeping with 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 individuals inner to the corporate and eight from exterior. The board reviewed not simply the information collected in the course of the mission, but in addition all the information from the flight qualification marketing campaign and part testing. In the long run, it decided that the doubtless explanation 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 because of the 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 choice to do Griffin’s propulsion system in-house, to do extra vertical integration,” Astrobotic’s mission director Sharad Bhaskaran mentioned. “We’d already developed quite a lot of the capabilities to do this propulsion integration. … This additionally burned down a few of the threat going into the Griffin program, which is way extra advanced than Peregrine.”
However Astrobotic engineers began encountering points with the unique vendor’s propulsion elements — specifically the PCVs. In August 2022, they switched to a distinct, unnamed PCV provider, and people valves have been put in on the lander.
A last set of exams 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 fantastic; the one which leaked was repaired. Whereas Bhaskaran acknowledged that the second PCV was recognized “as a threat in our threat register” because of the leak with the primary throughout testing, engineers in the end deemed that the failure was low as a result of the lander handed last acceptance testing.
He justified not changing the second PCV, saying it was situated a lot farther into the spacecraft and would have required “in depth surgical procedure” on the lander, invalidated the ultimate testing, and carried extra threat that comes with disassembly and reassembly.
Horack echoed that the crew’s decision-making was sound all through: “I actually discovered that, in wanting on the crew and taking a look at what occurred … I can’t see any choices that have been made within the movement main as much as the launch the place I might have mentioned, ‘Hey, I believe you need to have carried out this in another way.’”
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 gas and oxidizer tanks, and backup latch valves as added redundancy in case the problem reoccurs with a PCV.