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4$\begingroup$ "I could be forgetting some ..." Here's some: On 29 April 2013, ESA announced that Herschel's supply of liquid helium, used to cool the instruments and detectors on board, had been depleted, thus ending its mission. and Infrared Space Observatory; End of mission and Spitzer Warm mission and end of mission $\endgroup$– uhohCommented Jun 19 at 9:34
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2$\begingroup$ Also see answers to Which (if any) space telescope would have worked longer if it hadn't simply run out of helium? $\endgroup$– uhohCommented Jun 19 at 9:34
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1$\begingroup$ It is worth mentioning that gyro and reaction wheel failures could have been due to coronal mass ejections (CMEs) from the Sun causing arcing between the metal bearings and races. Space missions have changed from metal ball bearings to ceramic bearings in their reaction wheels, greatly reducing the chance of arcing across the bearing races. hackaday.com/2018/09/11/… $\endgroup$– XavierCommented Jun 19 at 23:15
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2$\begingroup$ Hubble had six gyros and got them all replaced during one of the service missions. That's 12 gyros. How many more do you think it needed? $\endgroup$– Darth PseudonymCommented Jun 20 at 14:09
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2$\begingroup$ You load the vehicle with 5 gyros and 1 unit of fuel. The fuel runs and for the next mission you put 2 units on board. This next mission eventually all the gyros fail and for the next one, you put 8. But this next mission all the fuel runs out, so next time, you put 3 units on board, and so the loop continues. At what point do you say enough is enough? $\endgroup$– Bob GoddardCommented Jun 20 at 16:57
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