Astrobotic’s Peregrine lunar lander mission faced a major setback due to a problem with a single valve in its propulsion system. The issue occurred shortly after the launch on January 8 when the spacecraft’s propulsion system was activated for the first time. Helium began to flow uncontrollably through the second valve into the oxidizer tank, causing over-pressurization and subsequent leakage of oxidizer for the remainder of the mission. The valve failed to reseal, likely due to a mechanical failure caused by vibration-induced relaxation between threaded components.
A review board consisting of 34 members, including internal and external experts, was assembled to investigate the failure. The board analyzed data from the mission, as well as data from the flight qualification campaign and component testing. It concluded that the failure of the single helium pressure control valve was the likely cause of the malfunction.
The timeline of events leading to the failure traces back to 2019 when Astrobotic contracted a vendor for the development of the propulsion feed system. However, due to technical and supply chain issues caused by the COVID-19 pandemic, Astrobotic decided to terminate the contract in early 2022 and complete the partially assembled feed system in-house. This decision was part of the company’s strategy to increase vertical integration and reduce risks.
Although Astrobotic encountered issues with the original vendor’s propulsion components, they made the switch to a different supplier in August 2022. A final set of tests revealed leaks in one of the pressure control valves, but not the one that ultimately failed during the mission. Despite identifying the second valve as a risk, engineers deemed the failure probability to be low based on the lander passing final acceptance testing. Replacing the second valve would have required extensive surgery on the lander and carried additional risks.
The findings from the review board’s report have already influenced the development of Astrobotic’s upcoming Griffin lander. Engineers have redesigned the valve and introduced additional redundancy measures, such as a regulator to control helium flow and backup latch valves. These improvements aim to prevent a recurrence of the valve failure in the propulsion system.
The lessons learned from the Peregrine mission will be valuable for the success of future lunar missions. Astrobotic is determined to apply these insights to ensure the reliability and performance of the Griffin lander, which is scheduled to launch before the end of 2025. The company’s commitment to addressing the issues and implementing necessary improvements demonstrates its dedication to advancing space exploration and overcoming challenges in lunar missions.
