"The backup roll thrusters in use are now at risk due to residue buildup in their fuel lines, which could cause failure as early as this fall." If anyone was c

"The backup roll thrusters in use are now at risk due to residue buildup in their fuel lines, which could cause failure as early as this fall." If anyone was curious where residue comes from in hypergolic fuel systems, the answer is it's SiO2 (silica) from decaying rubber components, "After 47 years, a fuel tube inside the thrusters has become clogged with silicon dioxide, a byproduct that appears with age from a rubber diaphragm in the spacecraft’s fuel tank". ┕ https://science.nasa.gov/missions/voyager-program/voyager-1/voyager-1-team-accomplishes-tricky-thruster-swap/ https://science.nasa.gov/missions/voyager-program/voyager-1/... An HN commenter tracked down relevant documentation on NTRS, "They expel the Hydrazine(N2H4) fuel out of a spherical Ti tank by inflating a rubber balloon that involve Teflon inside the tank using helium supply. I guess N2H4 was potent enough to degrade even those space age materials." https://ntrs.nasa.gov/api/citations/19810001583/downloads/19810001583.pdf https://ntrs.nasa.gov/api/citations/19810001583/downloads/19... ┕ https://news.ycombinator.com/item?id=41525267 https://news.ycombinator.com/item?id=41525267