Once at Mars, cargo and crew ships will be captured by the Martian atmosphere using an aerocapture maneuver. Aerobraking, parachutes, and thrusters will be used to get the spacecraft safely on the surface. The astronauts will arrive in a crew module that will house them for the trip and while on the surface. Previously sent cargo ships will provide power, return propellant production, and surface life support. For a paper about some of the crew surface activities, click here.

In the 1997 NASA Mars Exploration Scenario a launch vehicle, using propulsion systems with space shuttle heritage, boosts one stage of a Mars spacecraft into Earth orbit. Two such launches are required to put a complete Mars-bound vehicle in Earth orbit. A fully assembled Mars spacecraft is checked out in Earth orbit and made ready for its voyage to the red planet. With all engines running, the crew and their spacecraft leave Earth orbit and begin their 6-month voyage to the red planet.

 Prior to their takeoff, the first cargo ship has arrived and put into production the propellant factory that will produce fuel for the crew’s return trip. The cargo ship has also brought additional supplies for the crewed mission.

After a 125 million mile journey in space, the ship reaches the planet Mars. The lander uses atmospheric breaking to decelerate prior to landing. After landing on the Martian surface, the crew uses an unpressurized rover to unload cargo and supplies needed for their stay on the red planet.

The crew attaches an inflatable laboratory to their lander to increase the internal pressurized volume of their Martian home. The completed outpost on Mars includes the crew's two-story lander habitat, an inflatable laboratory, and the unpressurized rover. After the habitats are joined, the crew has multiple pressurized volumes available for conducting greenhouse experiments, biological research, and geochemical analysis of samples and for general crew accommodations. The crew's ascent vehicle and propellant production facility are located near the completed outpost.

After spending nearly 500 days on Mars, the crew begins their 180-day voyage back to Earth by ascending into orbit to rendezvous with their Earth-return vehicle. Subsequent human missions have the option of returning to the site established by the first crew or placing additional footholds on the surface of Mars. The Earth return vehicle has awaited the crew's arrival in Mars orbit for nearly 3 years.

After checking out the ERV's systems, the crew takes off on their journey in the now-familiar Mars habitat. This familiarity will pay off in terms of increased crew safety and reduced program costs.

Having spent nearly 900 days away from home, the crew returns to Earth landing at the Kennedy Space Center.

Questions to think about:

• Which systems would need to be checked out on Mars from the unmanned cargo ship before sending the crew ships?

• How would you go about checking these systems from Earth?

• What would happen if there was a failure of one of these systems before the human crew arrived?

Propulsion Systems