It's rare that an inanimate object gets a Crowning Moment of Awesome, but Pathfinder does. After Mark explains to the audience what might be wrong with it, how he hopes he fixed it, and how he'll know if it's been fixed (the high-gain antenna orienting towards Earth, because Earth sent a signal telling Pathfinder where it was to do that), the chapter concludes with Pathfinder's boot log, including a bunch of nonfunctional systems (that were on panels of the probe Watney removed to take it back to the Hab). Finally, the last lines of Pathfinder's computer humming away close out the chapter:
LISTENING FOR TELEMETRY SIGNAL. . . LISTENING FOR TELEMETRY SIGNAL. . . LISTENING FOR TELEMETRY SIGNAL SIGNAL ACQUIRED. . .
Mark Watney proves he is the foremost expert on survival on Mars, in four words spelled out with rocks in Morse code for NASA's orbiting satellites:
DUST STORM. MAKING PLAN.
You've been injured and left for dead on a planet however many millions of miles away from any other human being. You expect that it will take four years for a manned rescue mission to get to you, and you're in a habitat designed to last 31 days. It would be so easy to give in, wait for the food to run out or some essential life-support system to break. And then...you speak five words that lead into all the awesomeness to come:
Watney: In the face of overwhelming odds, I'm left with only one option: I'm gonna have to science the shit out of this.
A man grows potatoes. On Mars.
Mark Watney: In your face, Neil Armstrong.
With little bacteria and less than a tenth of the necessary water readily available. He "sciences the shit" out of both problems.
He later says that technically you've officially colonized a place when you first grow crops, meaning that he is the first true colonist of Mars.
The sheer audacity of sending a man into orbit with no more protection than a flimsy tarp, alongside the courage of the man in question to go through with the mad scheme. Against all expectations, it works.
Rich Purnell, a seemingly random kid, figures out the exact math for getting the Hermes back to Mars in time to save Watney. "Steely-eyed missile man" is a traditional NASA accolade for someone who comes up with an ingenious solution quickly while under pressure. It's the highest compliment that can be paid to someone at NASA. In the whole story, it's only ever applied to one person: Rich Purnell.
The Hermes crew have a decision to make: They can follow NASA's direct orders and land the ship back on Earth, likely dooming Watney to die on Mars...or they can go along with Purnell's plan, technically commit an act of mutiny, and stay in space for many more months — with all the risks to themselves that the trip would entail — to take their shot at saving their friend. If even one member of the crew decides to go home, they all go home. Despite knowing all the risks and everything they would be giving up, not one member of the crew says "no".
The scene where the Hermes crew picks him up, even if it is made a bit more dramatic than it was in the book, is undeniably awesome.
The entire Hermes crew proves that Watney is not the only guy who can science the shit out of a problem by building a bomb that blows out an airlock and vents out air, which allows the ship to decelerate fast enough to improve the viability of Watney's extraction.
Tony Stark, your lies have been exposed. Mark Watney is Iron Man.
There's something distinctly awesome about Watney proclaiming himself a "Space Pirate".note Since Mars doesn't belong to a country, it legally counts as international waters, and Watney must take control of the Ares 4 MAV without anyone giving him explicit permission to do so, making him technically a pirate. Call him "Captain Blondbeard".
Space exploration is inherently awesome, but Watney takes it to eleven. Doubly awesome in the book, where Watney explains that he never expected to be "the first" at anything. He was on the third manned mission to Mars, and wasn't even first out on his own trip. Instead, he accumulates a massive number of "firsts" during his ordeal. Even the Hermes crew get in on it, being the first crew to go to Mars twice, something even Watney cannot lay claim to.
Watney: Everywhere I go, I'm the first. It's a strange feeling. Step outside the rover? First guy to be there. Climb that hill? First guy to do that. Four and a half billion years, nobody here. And now, me. I'm the first person to be alone on an entire planet.