After NASA holds a funeral for Watney, satellite planner Mindy Park reviews images of the Hab area and realizes he has survived. NASA administrator Teddy Sanders has the news released, but despite the objections of the Hermes flight director Mitch Henderson, decides not to "distract" the Ares III crew by informing them.

Watney takes the rover to retrieve the nearby Pathfinder probe, which fell silent in 1997. Using Pathfinder's camera and its motor, he establishes rudimentary two-way communication with Earth, first using simple signs, and then sending and receiving ASCII in hexadecimal. NASA sends a software patch to link the rover with Pathfinder and communicate via text. Watney becomes angry when he learns that the crew has not been told of his survival, and Sanders reluctantly lets Henderson finally inform them.

Henderson and Jet Propulsion Laboratory (JPL) director Bruce Ng prepare an Iris space probe to deliver enough food to last Watney until Ares IV's arrival. Meanwhile the Hab's airlock malfunctions due to a small puncture, destroying Watney's crops. Sanders orders the team to skip the usual safety inspections to launch the probe sooner, but it fails 40 seconds after liftoff. Watney now feels his death is inevitable.

The China National Space Administration has been developing a powerful classified booster rocket, the Taiyang Shen. Feeling camaraderie with NASA's scientists, they violate their government's secrecy and offer it to repeat the Iris mission. As Watney is still at more risk the longer he waits, JPL astrodynamicist Rich Purnell devises an alternative plan: send the Taiyang Shen with supplies to the Hermes, which will use Earth's gravity to "slingshot" back to Mars two years earlier. Sanders rejects the idea, refusing to risk the crew on Hermes, but Henderson surreptitiously sends them Purnell's plan. Risking their lives and careers, they vote unanimously for it, and make the necessary course change. Powerless to stop them, NASA concedes the issue.