Ares IV

Lore & Background

Ares IV is conceived as a proof-of-concept crewed mission: a brief, tightly scheduled stop at Mars to demonstrate that humans can land, operate, and depart. The four-person crew spends their time at a single pre-selected landing site, conducting surface operations, testing equipment, and preparing the Hermes for the return transit. The mission is deliberately compact—weeks, not months—so that the crew never has to live in the harsh Martian environment for an extended period. It is, in the story's world, the first time humans set foot on another planet, and the international consortium behind it treats every day as a milestone.

The mission's defining moment arrives near its end. As the crew prepares to load the Hermes and begin the long transit home, they spot the habitat from orbit and notice the flag is still upright, the solar array configuration has changed, and the rover has been moved. Commander Beck and the crew confirm what they already suspect: Watney, who was supposed to be dead, is not. The discovery is met with a stunned silence that the narrative lingers on, because the crew now understands that their clean departure is over. They will have to go back.

Ares IV's role does not end with the discovery. The crew is recalled to Earth, and the Hermes is repurposed as the rescue vehicle for the Ares III mission. The spacecraft that was built to carry four astronauts for a brief surface stay becomes the vehicle that must carry them all the way back to Mars, around Earth, and back again—a trajectory no one had planned for. The mission's original purpose is entirely subsumed by the rescue, and the crew's identity shifts from explorers to rescuers.

In Their Own Story

The Hermes hummed at a low, almost subliminal frequency, the kind of vibration you felt in your molars before you registered it with your ears. Beck floated near the forward viewport, coffee pouch tethered to her wrist, watching the ochre smear of the Ares IV site shrink toward the limb. Kapoor was running the final systems checklist, his voice a flat monotone of confirmations. Pineda and Meshram were in the rear compartment, packing the last of the surface samples into their canisters.

"Commander." Kapoor's voice changed. Just a half-degree of something. "You need to see the optical feed."

Beck unclipped and drifted forward. On the screen, the habitat sat in its familiar patch of dust, and the flag—blue, white, red, and the four agency emblems—stood at a full ninety degrees. It should have been buried. It should have been torn. The dust storm that had taken Watney from their lives should have flattened it to the ground.

It was standing. And the rover was three hundred meters from where they'd left it.

Nobody spoke for a long time. The Hermes kept humming. Somewhere far below, in a pressurized habitat that was supposed to be an empty shell, a man was alive.

Reader's Guide

The Ares IV mission is a deliberate narrative compression. In the real world, a crewed Mars transit takes roughly six to nine months one way due to orbital mechanics—Earth and Mars only align for a launch window every 26 months. A 31-day Mars stop is not physically possible with current or near-future propulsion. The story takes this license to keep the crew in the Mars system when Watney's survival is discovered, which is the entire engine of the plot. Without that compression, the rescue would be years, not weeks.

What IS grounded in real physics: the concept of a low Mars orbit for a brief surface stop is sound. A spacecraft can enter a low elliptical orbit around Mars, deploy a lander, and depart within days. The Hermes as a reusable crewed spacecraft is inspired by real proposals (NASA's earlier Mars Direct and various ESA/JAXA concepts). The four-person crew size matches real crewed-vehicle design logic.

The Ares III rescue, which Ares IV enables, is where the story gets more creative: slingshotting around Earth to gain velocity, then heading back to Mars, is a real orbital-mechanics technique (a gravity assist), though the timing and fuel requirements in the story are simplified for pacing. The core idea—that you can use a planet's gravity to redirect a spacecraft—is textbook astrodynamics.

Did You Know?

• The name Hermes references the Greek messenger god, fitting for a spacecraft whose entire purpose is to carry a crew to and from another world.
• The Ares IV mission is a joint operation of four space agencies—NASA, ESA, JAXA, and CSA—reflecting the international-cooperation ethos that runs through the story.
• In the novel, the crew's discovery of Watney's survival hinges on a single visual detail: the flag is still standing and the habitat's exterior has been altered, visible from orbit.
• The Hermes is repurposed mid-story from a one-way crewed transport into the vehicle for the Ares III rescue, a role it was never designed to play.