How long does it take to dissolve 1 kilogram of nitrogen in 15 kilogram of hydrazine? A not-so-little spacecraft called out for help, and in less than two hours, the internet found an answer.

ISEE-3, the spacecraft from the 1970s that a crowdfunded project is trying to hijack into doing more science, needs your cleverness. The reboot team managed to build a hardware emulator to overcome the whole, "We ripped out the antenna required to talk to it..." problem, the satellite obeyed commands to spin up to full operational rotations, and everything was good to go for an orbit-changing burn.

Except it didn't burn.


ISEE-3 uses a monopropellant hydrazine propulsion system, with nitrogen as the pressurant. That nitrogen might have been depleted, but it might have just dissolved into the hydrazine. The team was working on troubleshooting what was going on, but knew that orbital dynamics waits for no one. So, they put up a call for a distributed literature review on the chemistry of 1970s propulsion systems.

Knowing the denizens of io9 are exactly the sort to learn things just for fun, and tuck away all sorts of esoteric knowledge for the day it might come in handy, I was getting ready to signal-boost and recruit you to help them. But the internet beat me to it.


Less than two hours after sending out a distress signal for help, engineers who worked on exactly these types of propulsion systems emerged from the digital wilderness to offer their hard-won experience. What the team learned was a mix of good and bad: solubility probably wasn't the problem impeding the satellite's thrusters. Awesome, they don't need to fix that! Boo, they only have about two or three more options of things that are fixably bad to work on. And if none of those are the problem? Then this will be a glorious, exciting, exuberant failure, and ISEE-3 will continue on its orbit about the sun, leaving us behind once more.

Good luck, team. We're cheering for you.