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Stranded on Mars after an Ares 3 dust storm, the crew left botanist Mark Watney behind, believing him dead. He extended roughly 400 sols of food toward a 4-year wait for rescue by planting the crew's vacuum-packed Thanksgiving potatoes in Martian regolith. The same improvised system nearly killed him when a hydrazine miscalculation filled the Hab with explosive hydrogen, and it failed for good when an airlock breach froze the crop.
An overwhelming situation becomes survivable when it is broken into a chain of discrete, quantified problems: calories, water, oxygen, power, distance. Each problem is solved just well enough to reach the next one, so the whole mission is never faced at once. Progress comes from the size of the unit of work, not from optimism about the whole.
Stakes and tension can come from arithmetic rather than antagonists when the reader sees the numbers and knows the margin of error. Watching a character work out oxygen rates or rover range makes the reader a checker of the logic. A wrong assumption then lands as a plot twist, not an arbitrary disaster.
Watney's jokey log entries are not decoration but a working part of how he survives. Mockery shrinks catastrophe to a manageable size and keeps his mind clear enough to calculate. Seen this way, levity under lethal pressure signals an intact working mind, not denial.