On the advice of a NASA psychiatrist, Watney begins sending individual messages to the Ares 3 crew, beginning with Martinez, the pilot, and Johanssen (whom Watney lovingly calls a “hot chick” and a “nerd.”) The narrative pivots away from NASA for a moment, to the Chinese space authority (the CNSA), which has heard of the Iris probe failure. Two Chinese administrators, Guo Ming and Zhu Tao, discuss the possibility of offering the Taiyang Shen, a readymade booster rocket, to NASA. They would do this both to aid in the rescue of Mark Watney, and to create an arrangement with NASA, wherein the future Ares 5 mission could carry a Chinese astronaut into space. Guo Ming, head of the CNSA, calls Sanders, head of NASA, and the two agree to this emergency rescue arrangement on the spot. This plan would require a Mars probe to be re-made in under a month, then attached to the Taiyang Shen and sent immediately to Mars, where it would arrive six weeks after Watney’s supposed end-date for current food supplies. Although NASA and the CNSA recognize that this mission offers only slim hope for Watney, all scientists and engineers believe this is the best they can do to rescue him. Kapoor and others move ahead with the plan, until an astrodynamicist named Rich Purnell approaches Kapoor one day, saying he has another idea for rescuing Watney.
The narrative jumps ahead to Kapoor, who has heard out Purnell’s plan and thinks it might be superior to the rush-probe Taiyang Shen model currently on the table. As Kapoor explains to an incredulous staff, including Montrose and Sanders, the Taiyang Shen would no longer need to reach Mars, but would instead be launched into near-Earth orbit. It would include supplies for the crew of Ares 3, on their way back to Earth; the Ares 3 team, instead of landing on Earth, would pick up supplies and slingshot around Earth back to Mars. With the help of the “ion engines” on-board, the Hermes would reach Mars quickly (and for the second time), having accelerated continuously after the slingshot maneuver. This would place Hermes, with supplies, near Mars around a month before Watney’s current foodstuffs run out. Hermes wouldn’t be able to land on Mars, and so Watney, in his remaining projected year-plus on the Red Planet, would need to travel in the rover to the Ares 4 landing site at Schiaparelli, at relatively high speed. From there, Watney would modify the MAV already located at the Ares 4 landing site (in prior preparation for the Ares 4 launch), then launch into space to rendezvous with the Hermes, and Ares 3 crew, before returning with them to Earth.
Henderson, head of the Ares 3 crew, is strongly in favor of rescue mission, and believes the crew would be as well. Sanders and others worry that, if something were to go wrong with Hermes, six people would die, rather than only one, and the Ares program would not have enough funding to continue (as a single Hermes spacecraft is enormously expensive to build and maintain, as the narrator explains). Sanders thinks over the choice, and eventually decides against the Purnell maneuver, arguing that it’s too risky to put all those lives at stake for one person. Sanders believes this is the correct decision, but the rest of the high-ranking NASA staff, including Henderson and Montrose, think that Sanders is being a “coward,” essentially dooming Watney to die in order to preserve the Ares mission going forward, along with NASA’s funding and public image. Deeply upset, Henderson leaks the plans for the Purnell Maneuver to the crew of the Ares 3, who immediately realize what’s happened and, deciding together, vow to carry out the maneuver (essentially mutinying) to save Watney. Henderson meets with Sanders, who says he’ll fire Henderson eventually, when he can prove that Henderson leaked the information. But Henderson is defiant, and Sanders’s hands are tied: NASA announces that the Purnell Maneuver will be used to rescue Watney. Thus the Ares 3 crew will be slingshotting around the Earth to head back to Mars and pick up their long lost crewmate.
Watney is overjoyed at this news, and he begins carrying out NASA’s plans, which include modifying the rover to lose weight for the journey to Schiaparelli. He does this by way of a large drill, which can take out chunks of the rover’s material. By a freak mistake, however, Watney leans the drills against a conductive surface, which causes a surge of electricity to flow into the Pathfinder and blow it out, rendering it inoperable. Watney can’t believe his ill luck: the Pathfinder was absolutely essential for his Mars-to-Earth communications. As Chapter 17 ends, Watney wonders how he’ll be able to continue the rover-mod process without a comms link to Earth. He marvels at all the tiny things that can go wrong on Mars, leading to massive, dire consequences.
But Watney presses on. He continues his modifications of the rover, by figuring out how to power the “Big Three” (the oxygenator, atmospheric regulator, and water reclaimer) while simultaneously also powering the vehicle itself. He goes back to the RTG, which he’d reburied far away from the Hab, and which he’ll now drive with on the roughly two-month journey from the Ares 3 site to the Ares 4 site. Watney calculates how many potatoes he’ll be able to place in the rover, how he’ll maintain a heat reservoir for the RTG (via a standing container of water), and how he’ll tack on more solar panels to power the now-heavier vehicle. He also spells out Morse code messages for NASA to read, via satellite imaging back on Earth, saying that he’s continuing with the Schiaparelli plan and is set to drive soon.
The theme of patience and prudence is brought to the foreground once again in these crucial sections. It also comes into contact with another theme: that of calculated risk-taking, and of the trade-off between prudent, but limited, and risky, high-payoff plans. When the Iris mission goes bust, NASA is extraordinarily fortunate that the CNSA is willing, essentially, to donate a rocket for the American cause. Of course, in Weir’s rendering, the Chinese government asks for some concessions behind the scenes, but in any event the Taiyang Shen’s aid is central to the Watney rescue. With that said, however, NASA wants to proceed, even with the new Chinese rocket, along a similar course to the one Iris mapped out. But Iris failed, and NASA officials like Henderson worry that a rushed Taiyang Shen launch could be an even costlier failure.
Instead, Henderson and others at NASA advocate for a more expansive and imaginative plan, one taking into account the Ares 3 crew’s willingness to rescue Watney. This “riskier” plan actually places the Taiyang Shen on an easier path into space; but it also, as Sanders points out, spreads risk out, implicating more people—the whole Ares 3 crew—rather than, simply, Watney. Here the novel toys with what might be termed “categorical” and “utilitarian” ideas of ethics. Is it ever justifiable to endanger five people to possibly save one? Are lives inherently equal, or is it demonstrably the case that some lives stand in for more than others? Is Watney’s notoriety as a global celebrity enough to support the enormous expense in keeping him alive, and possibly steering crewmates toward their own demise?
Finally, in these chapters, the idea of moral responsibility on the part of the crew becomes apparent. Commander Lewis, as everyone at NASA seems to know, would do anything to rescue Watney. The crew feels they have let their fellow man down, even as Watney understands that nothing could have gone differently during the Martian sandstorm: the crew was acting in accord with NASA protocols. Nevertheless, Lewis wants to repair the wrong she feels she’s committed, and her fellow crew-members are equally up to the challenge. Although NASA worries about the lives that might be risked, Lewis and Co. seem to argue, implicitly, that they’re willing agents, and can decide for themselves to risk their lives for the sake of Watney.