Project Hail Mary

Grace completes another spacewalk to cut a six-inch sample of the Hail Mary’s hull for the Blip-A, wondering how they plan to reconcile their two environments for the tunnel, since the Blip-A’s atmosphere is hotter than the boiling point of water, judging by the temperature of the cylinders when they arrived at the Hail Mary. Grace tosses the hull sample toward the Blip-A and waves to the alien ship’s hull robot, which waves back.

Grace recalls another memory. On the aircraft carrier, Grace visits Dmitri’s lab, where the Russian scientist has designed a spin drive engine that uses Astrophage as fuel. The spin drive is extremely powerful, capable of melting a metric ton of metal in a fraction of a second. For redundancy and safety, the Hail Mary will have 1,009 small individual engines.

Back on the Hail Mary, the Blip-A approaches and uses its hull robot to attach a xenonite tunnel between the two ships, placed over the Hail Mary’s airlock. Grace gathers his courage and opens the airlock to find that the tunnel is divided in half, allowing Grace to pressurize his half with the Hail Mary’s atmosphere, and the Eridian half to be pressurized with Eridian atmosphere, since they are incompatible.