Roamy here. I previously wrote about the Stardust spacecraft here. This amazing spacecraft has been taking pictures and gathering data for over a decade, and it was helpful to spacecraft designers one last time before going dark. You know how the gas gauge reads “E” or the little gas pump light comes on, and you wonder if you have 25, 30, maybe 40 miles left? Or the gas gauge is like Mr. RFH’s 1976 Dodge Aspen, which would drop down normally until it reached a quarter-tank, then stop.
The details are here, but basically the engineers calculated how much fuel was left by three different ways then let the engines run until the tank was emptied. After more than 2 million main engine and reaction control system engine firings, this was it. This data will help with future missions, especially those with planned end-of-life, like a geosynchronous satellite that needs to be moved out of orbit before it dies.