Chapter 19 begins with Lewis, Vogel, Beck, Martinez, and Johanssen talking to their families over a close-link connection to Earth, as the Hermes nears its designated point for meetup with the Taiyang Shen supply mission. Johanssen reveals to her father that NASA has named her the “survivor” if the rendezvous should fail, meaning that she would pilot the Hermes, alone, back to Earth, and the rest of the crew would take suicide pills to ensure adequate food for Johanssen. (The Hermes is so expensive and valuable, and the deaths of the other crew-members would allow the Hermes to return and the Ares missions to continue).
Fortunately, this ghoulish contingency isn’t required. The Taiyang Shen blastoff occurs without incident, and Martinez docks the Hermes with the Shen’s orbiter, allowing for the transfer of foodstuffs into the Hermes. Watney continues with his rover modifications, for the long, long journey to Schiaparelli. He arranges for a “pop-tent” to be extended outside the rover, so he can stand during the day while en route, and can avoid the long-term sitting that characterized his previous rover drive. It turns out that Watney is able to anticipate most of the mods that NASA has been trying to send along, even though the Pathfinder radio system is no longer able to receive messages from Earth.
Meanwhile, the Hermes crew goes through small mods to their own ship, to make sure it can last the extra year-plus they’ll be traveling, in returning to pick up Watney. On Mars, after triple-checking his oxygen, water, carbon dioxide, and related systems, Watney begins his long drive to Schiaparelli. But on Earth, the NASA team worries about an impending, “low-velocity dust storm” that seems to be moving toward Watney as he goes. Watney won’t be able to see it for some time, but the storm will limit the effectiveness of the solar panels in soaking up sunlight, which will cause his speed to decrease rapidly. NASA can’t send any information to Watney about the storm, and they hope he’s able, somehow, to figure out it’s coming and adjust his course, so he can reach Schiaparelli on time, with his food stores intact.
This set of chapters presents the final, large hurdle Watney must clear before reaching Schiaparelli. The passage highlights how important communication is for Watney: that communication itself, in its many forms, is one of the major themes of the text. If Watney could speak to NASA, they’d be able, quickly, to alert him to the presence of the dust storm, and he could alter his course without much effort. But because this comms link has been severed, Watney must first discover that the dust storm is near; then he must figure out a system for measuring it and guessing the appropriate travel direction.
Fortunately, Watney’s resourcefulness comes in handy once again. He doesn’t panic, even though the storm has the potential to ruin his journey and keep him from reaching Schiaparelli. Instead, Watney trusts in his abilities, lays out a plan in small steps, and remains patient. Once he decides the storm is moving northward, he feels confident that a southern, then a western route will get him to Schiaparelli without undue loss of time. It turns out that Watney’s predictions are correct, and NASA rejoices at his decisiveness, even though they haven’t been able to speak directly to Watney throughout the ordeal.
The dust storm itself is a symbol of what would, on Earth, be called “nature”: the power of the non-man-made world, which can affect the decisions humans make and throw off even the best-laid plans. Watney knows he can’t control the dust storm, and no amount of anger will make it go away. Instead of trying to overpower nature, Watney contents himself with cleverly outrunning it, allowing him to reach Schiaparelli even as the storm rages. And, of course, it was an initial dust storm that stranded Watney on Mars: if there’s anything like an “antagonist” on the Martian surface, it might be the specter of a dust storm itself.