The Kepler telescope is running on empty, and there's no way to fill up the tank. As the groundbreaking mission nears its end, the engineers' last priority is retrieving the months of data stored on the spacecraft.
And so on August 2, the craft will be awakened from hibernation (NASA describes it as a no-fuel-use-state) and instructed to point its antenna toward Earth. Over a four day period, Kepler will download data during its scheduled Deep Space Network time. Assuming the repositioning and data transmission are successful, Kepler will then resume its observations with any remaining fuel — until it shuts its eyes for good.
Kepler’s time has been drawing to a close since March 2018, when Charlie Sobeck, an engineer for the Kepler mission, announced in an update that the end was near for the nine-year old deep space observatory. “At this rate, the hardy spacecraft may reach its finish line in a manner we will consider a wonderful success,” he wrote. “With nary a gas station to be found in deep space, the spacecraft is going to run out of fuel. We expect to reach that moment within several months.”