The beetles and Earth's data transmission relationship

The beetles are four unmanned probes carried aboard the Hail Mary, designed to return scientific data to Earth after the crew completes its mission at Tau Ceti. They represent the only reliable channel for transmitting humanity's salvation back home, and their launch and eventual success become the decisive link between the Hail Mary's discoveries and Earth's survival.

Design and Purpose

The beetles were developed by Steve Hatch, a Canadian engineer from the University of British Columbia, who brought a prototype to the Hail Mary project. Each beetle is a small, self-contained spacecraft with a bulbous fuel bay, a triangular head containing cameras and a computer, and a trapezoidal rear housing a spin drive based on Russian designs. The probes are named after the Beatles: John, Paul, George, and Ringo. Hatch explained that the beetles use ordinary visible light to identify constellations and determine their orientation, and they carry a redundant RAID array with more memory storage than anyone would ever need. The bulk of each probe is fuel storage, requiring about 125 kilograms of Astrophage to make the twelve-light-year journey back to Earth. Unlike the Hail Mary, which is limited by the soft, squishy humans inside, the beetles can accelerate at five hundred g's until they reach a cruising speed of 0.93 c, experiencing only about twenty months of subjective time during the trip while over twelve years pass on Earth.

Role in the Mission

The beetles are the only means of getting information back to Earth. Grace realizes early in his recovery that the Hail Mary is a one-way ticket and that the beetles are how he is supposed to send information home. There are four of them for redundancy, and each carries 5 terabytes of data storage. Grace discovers that the beetles can be launched from a control panel in the Hail Mary's cockpit, and they orient themselves based on stars and head toward Earth on their own. The beetles are stored in the nose of the ship, and Grace must perform a dangerous EVA on the spinning ship to retrieve them after the Taumoeba contamination destroys the Hail Mary's fuel.

Modification and Use as Emergency Engines

After the Taumoeba infestation leaves the Hail Mary dead in space, Rocky modifies three of the beetles—John, Paul, and Ringo—to serve as makeshift engines. He bypasses their computer controls and jerry-rigs the spin drives to be activated by an audio-driven remote control. Rocky mounts the three modified beetles on the hull, each angled forty-five degrees out away from the centerline of the ship, and uses them to zero out the ship's rotation and then to propel the Hail Mary back toward the Blip-A. Grace keeps one beetle, George, unmodified and in reserve, ready to fulfill its original mission.

Launch and Final Mission

After deciding to rescue Rocky rather than return to Earth himself, Grace launches all four beetles toward Earth. Each beetle carries a mini-farm containing Taumoeba-82.5, the nitrogen-resistant strain that can survive on Venus, sealed in Eridian steel capsules that the Taumoeba cannot penetrate. Grace also includes USB sticks full of data and findings. The beetles accelerate at five hundred g's and head for Earth, and Grace watches their engine flares fade into the distance. Years later, on Erid, Rocky brings Grace the news that Sol has returned to full luminance, confirming that the beetles reached Earth and that the Taumoeba solution was successfully implemented. The beetles' data transmission relationship with Earth is thus the mechanism by which humanity is saved, even though Grace himself never returns.