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Friday, September 24, 2021

CONTINUITY: Boeing Starliner OFT-2 “Hangar Queen”—NASA Says “Will Likely Not Launch Until Next Year”

Boeing officials said last month that nitrogen tetroxide, an oxidizer consumed by Starliner maneuvering thrusters in combination with hydrazine fuel, leaked through Teflon seals in the valves. That is normal, Boeing officials said, but the nitrogen tetroxide reacted with water vapor that somehow made its way into the service module, creating nitric acid that corroded the valves and caused them to stick.

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Twenty-four regulate the flow of oxidizer to the Starliner spacecraft’s thrusters used for in-space maneuvers. Boeing initially detected problems with 13 of the 24 oxidizer valves.

Officials will decide in a few weeks whether to repair the valves in the service module, or use a new service module for the OFT-2 mission. If Boeing goes with a new service module, the current service module might be repaired and used on a future mission, [NASA Space Operations Mission Directorate associate administrator Kathy] Lueders said.

Boeing officials said last month it was too early to know whether the valves might need to be redesigned, or whether ground teams could take more steps to ensure moisture does not get into the valves.

Reaction control thrusters using hydrazine and nitrogen tetroxide propellants are a technology that has been in use for more than six decades. The Boeing Starliner has been under development for more than one decade, and was originally planned to be operational in 2015. In 2014, still under development and not having flown, Starliner won a US$4.2 billion NASA contract to complete and certify the capsule and conduct one crewed flight by 2017. At the same time, SpaceX was awarded US$2.6 billion to do the same with their Crew Dragon spacecraft. To date Crew Dragon has completed four crewed space flights.

Posted at September 24, 2021 10:42