The Hermes Program
The bridge between Earth and Mars.
The Hermes Program was NASA's cornerstone for long-duration interplanetary travel, a reusable nuclear-powered spacecraft designed to ferry astronauts between Earth and Mars. Assembled in orbit from modules launched by international partners, Hermes represented humanity's most ambitious leap into deep space, enabling the Ares missions that sought to establish a permanent human presence on Mars.
Quick Facts
- Role
- Interplanetary transport vehicle for Ares missions
- Affiliation
- NASA
- First appears
- The Martian (novel/film)
- Status
- Active (as of the end of the Ares III mission)
- Propulsion
- Nuclear-powered ion drives
- Crew capacity
- 6 astronauts (standard Ares mission complement)
Lore & Background
The Hermes spacecraft was a marvel of engineering, built over years of international collaboration. Its ion propulsion system, powered by a nuclear reactor, allowed for efficient travel, drastically reducing travel time between Earth and Mars compared to conventional chemical rockets. The ship was designed for modularity, with habitation modules, laboratories, and storage sections that could be reconfigured for different mission needs. Its life support systems were closed-loop, recycling air and water to sustain a crew of six for months in deep space.
Hermes was not just a vehicle but a symbol of humanity's collective ambition. It served as the home and workplace for the Ares crews during their months-long journeys, and its reliability was tested to the limit during the Ares III mission. When Mark Watney was stranded on Mars, Hermes became the linchpin of the rescue plan, requiring a daring slingshot maneuver around Earth to return to Mars faster. The ship's design prioritized crew safety and redundancy, with backup systems for critical functions.
Its ion drives, while efficient, required careful management of propellant and power, making every mission a delicate balance of resources. Hermes used a rotating section to generate artificial gravity, mitigating the health effects of prolonged weightlessness.
Reader's Guide
The Hermes Program was NASA's answer to the impossible: a reusable spacecraft that could make multiple trips between Earth and Mars without being discarded after each use. Powered by a nuclear reactor feeding xenon ion drives, Hermes offered continuous, gentle thrust—accelerating day after day to cut transit times from months to weeks. The ship was built in orbit, a jigsaw puzzle of modules launched by the U.S., Russia, Europe, and Japan over several years, then mated together by spacewalking crews.
Hermes served as the transport for the Ares missions, each crew spending months aboard during the journey. Its design included living quarters with private bunks, a galley with a fold-down table, a gym with elastic resistance bands, and a laboratory for experiments—all optimized for long-duration habitation. The ship's rotating section, a ring of hab modules spun to create artificial gravity, helped prevent bone loss and muscle atrophy, giving the crew a taste of weight they'd miss on the Martian surface.
Every system—from the water recycler that turned sweat into drinking water to the backup oxygen generators—was built with redundancy, because in deep space, there's no hardware store.
Frequently Asked Questions
What role does Hermes play in the story of The Martian?
It is the only vehicle linking the Ares III crew to Earth, effectively the sole lifeline across the void between the two planets. When the mission derails, every rescue plan NASA devises ultimately hinges on repositioning Hermes to reach Watney.
How many astronauts can Hermes carry?
The ship is sized for the standard Ares mission complement of six crew members. That is the same configuration the Ares III team used when they departed Earth and when they were later evacuated.
What happens to Hermes after the Ares III rescue?
The spacecraft remains an active, operational asset in NASA's fleet at the story's close. Having proven itself as the workhorse of human interplanetary travel, it stands ready for whatever comes next in the program.
More in Science & Lore
Elsewhere in The Martian
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced