Chapter 20

Mark Watney finishes key rover and trailer modifications, focusing on sustaining life support. He balloons the trailer with pop‑tent canvas to house the oxygenator and regulator, routes the AREC outside through spare valve patches, and mounts it under the solar shelves. He proceeds methodically, limiting EVAs to avoid injury.

To handle cold return air, Watney builds a heat reservoir: he vacuum-bags the RTG, submerges it in a 20‑liter water container, and diffuses regulator return air through a perforated coil to capture heat. Tests show it cannot heat the Hab but will easily keep the rover warm.

Watney studies Martian law tongue-in-cheek, dubbing himself a future “space pirate,” then plans his traverse. Using low-detail satellite maps, he identifies elevation hazards and a crucial relief: Mawrth Vallis, a gentler valley offering about 1,350 km of easier travel before the rough Arabia Terra and the descent into Schiaparelli.

To avoid living cramped for 100 sols, he designs a larger “bedroom” tent attached to the rover’s airlock. Lacking canvas, he depressurizes the Hab, cuts large strips, reseals the now lopsided dome, and finds leaks with Martian dust before achieving a solid seal. Inside the Hab, he assembles the tent on joined pop‑tent floors, then successfully pressure-tests it and attaches it to the rover.

Watney inventories food, water, air, power, heat, and emergency CO2 filters, confirming the rover system is ready. He sets a departure date of Sol 449, leaving 59 sols for testing, route plotting, and final checks, acknowledging both the fear of leaving the Hab and the resolve to proceed.