The high cost of a human expedition to Mars is the result of these factors:

1. The Space Shuttle is the chosen launch vehicle for placing the Mars Mission hardware in orbit, and the Space Shuttle is extremely expensive to operate.

2. The mission will take years to complete, and facilities must be provided to protect the crew from radiation and weightlessness, as well as life support and consumables for the duration. This increases
the mission weight, and consequently the cost.

3. A unique propulsion system and lander vehicle must be designed.

All of these problems go away, however, with SSTO . . .

1. SSTO vehicle takes off from spaceport on Earth.

2. A robotic fuel barge is constructed and filled with fuel in orbit.

3. The fuel barge makes a long, slow, but efficient trip to Mars.

4. With tanks refueled in orbit, the astronauts sprint to Mars in mere weeks aboard SSTO.

5. The fuel-empty SSTO vehicle relies on atmospheric braking to slow it into Mars orbit.

6. Rendezvous and refueling with the robot barge in Mars orbit.

7. The SSTO vehicle descends to the Martian surface.

8. The astronauts have weeks for exploration.

9. Ground mission complete, SSTO blasts off back to Mars orbit.

10. Fueling for the trip Home.

11. The astronauts sprint back to Earth.

12. Atmospheric braking slows the vehicle into Earth orbit.

13. In the future: a permanent facility extracts fuel from Phobos.