Item from Project Hail Mary by Andy Weir
Four unmanned probes named after the Beatles — humanity's insurance policy, carrying five terabytes of hope at ninety-three percent the speed of light.
The Beetle probes are Steve Hatch's contribution to the mission: four unmanned return craft named John, Paul, George, and Ringo. Each carries five terabytes of data storage, star-tracker navigation, reaction wheels for attitude control, and enough Astrophage fuel to reach 0.93 times the speed of light. They are the backup plan for the backup plan. If the crew dies (and two-thirds of them did), if the mission fails, if Grace can't get home — the Beetles can still carry the answer back to Earth. The twelve-year return trip (Earth-frame) means the data arrives long after the crisis began, but late information beats no information when extinction is the alternative. Grace launches the Beetles with Taumoeba data before making his final choice to save Rocky instead of returning home. The probes become his legacy — the last message in a bottle, thrown across twelve light-years of void.
Four compact unmanned spacecraft, each roughly 125 kg of Astrophage fuel plus data storage and navigation systems. Housed in an isolated compartment at the tip of the Hail Mary's spacecraft adapter. Simple, functional, designed for one job: get data home.
Also known as: Beetles, John Paul George and Ringo