Contents
Chapter 3
Overview
Mark Watney recalculates his survival needs and expands potential farmland inside the Hab and via two rover pop-tents, but faces a severe water shortfall. He plants a seed crop from twelve potatoes and devises a risky plan to manufacture water by generating oxygen from CO2 and hydrogen from MDV hydrazine.
The plan could sustain large-scale farming but introduces explosive hazards and ammonia contamination, raising the stakes for every step he takes.
Summary
On Sol 25, Mark Watney runs calorie math: to survive ~1425 days until Ares 4, he needs to generate ~1100 calories per day beyond his rations. He expands potential farmland from 62 to 126 m² by repurposing Hab floor space, bunks, lab tables, and two rover pop-tents, but identifies a 250-liter water deficit that blocks full cultivation.
On Sol 26, Watney hauls a cubic meter of soil into the Hab, cleans dusted solar panels after a brief storm, and performs another “dirt-doubling.” He starts a seed crop by quartering twelve Thanksgiving potatoes (ensuring eyed pieces) and planting them, planning accelerated growth via higher Hab temperature and controlled light.
By Sol 29, he reinforces bunks and tables to hold soil and deploys both pop-tents. Unable to mate their airlocks to the Hab, he accepts air-loss per ingress/egress but solves it by feeding each tent with an equalizer hose from the Hab to replenish lost air, then fills them with soil.
On Sol 30, Watney formulates a water plan. Oxygen will come from CO2 collected by the MAV fuel plant and processed by the oxygenator, yielding enough O2 for ~250 liters of water after ten sols. For hydrogen, he targets the MDV’s 292 liters of leftover hydrazine, cracking it over a catalyst to produce H2 and N2.
Watney recognizes the severe risks: hot hydrogen in oxygen could explode, and incomplete reactions will leave ammonia, but the hydrazine offers far more hydrogen than needed. Despite the danger, he resolves to proceed, as water is essential to hydrate the expanded farmland before the next soil-doubling.
Who Appears
- Mark WatneyBotanist-engineer protagonist; expands farmland, plants seed potatoes, deploys pop-tents, and devises a hazardous plan to make water.
- Rick MartinezPilot of the MDV; his efficient landing left ample hydrazine, enabling Watney’s hydrogen source for water.
- Melissa LewisCommander; her personal data-stick provides entertainment as Watney unwinds after labor.
- Beth JohanssenSystems operator; her Beatles collection is noted as Watney seeks different media.