The Hermes spacecraft, the result of a decade-long collaboration between NASA, ESA, Roscosmos, JAXA, and ISRO, is the crew transport spacecraft of the Ares Program, built to transport astronauts from Earth to Mars orbit and back. According to astrophysicist Neil deGrasse Tyson, in the universe of The Martian, it is "the most complex and expensive object ever built".
Hermes was constructed in low Earth orbit using the SpaceX space station as a building platform, with individual parts transported to the station piece by piece. The process was tedious, but its results established a new era of space travel.
Hermes was completed and flew its first mission, Ares I, in 2029. Hermes is currently commissioned for six missions in total, from Ares I to Ares VI (the latter a later addition to the Ares program); afterward, it is scheduled to be re-purposed as the new International Space Station, to be replaced by the Olympus spacecraft for further Ares missions from Ares VII onwards.
Prior to departure, crews fly to Hermes in orbit on a transport shuttle.
Electrical power on Hermes is provided by its onboard nuclear reactor as well as its solar panels. The spacecraft's ion propulsion system uses argon and electric energy to churn out positive ions and propel the spacecraft forward in continuous acceleration. While aboard, Hermes's rotating gravity segment generates a degree of artificial gravity to allow the astronauts ease of mobility and to maintain sufficient muscle tone in space, protecting them from the effects of long-term weightlessness. Hermes is also equipped with state of the art radiation shielding to insulate the spacecraft from solar and cosmic radiation (which can cause cell damage and cancer) as well as an array of advanced life support systems such as its oxygenator and water reclamation processors which allow it to sustain human life for extended durations.