So, dispite paying a billion dollars to develop Mars Observer, NASA claims it still didn't have enough money to install proper fuel values? Bullshit. That would be typical NASA mismanagement. No matter how much money they have, it just doesn't seem to be enough. What makes you think Mars Direct would be an exception?

Second, you seem to misunderstand how flight test works and how that relates to the history of the space program. Apollo was very much an incremental effort built on top of technology developed and tested in the Gemini program. Mercury was interested with developing some very rudimentary capabilities, namely getting a man into space and returning him alive. It did that well for the most part.

Gemini developed many essential technologies and tested them on increasingly difficult missions. These included:

1. Spacecraft mounted computers
2. Orbital maneuvering
3. Orbital rendevous
4. Docking
5. EVAs
6. Extended duration (2 week) missions
7. Fuel cells for electrical power

The Apollo missions were likewise a case of incremental flight test.

1. Apollo 7 tested the CM/SM in Earth orbit.

2. Apollo 8 was the first manned Saturn V flight. It sent a CM/SM to orbit the moon, testing the tracking, communications, and navigation capabilities.

3. Apollo 9 tested the LM for the first time, in Earth orbit.

4. Apollo 10 was a dress rehersal for the moon landing, sending a LM to orbit the moon down to 10 miles altitude.

5. Apollo 11 was the first landing.

6. Apollo 12 proved high accuracy landings were possible and extended the EVAs.

7. Apollo 14 tested a cart to carry materials on the moon. Not very successful.

8. Apollos 15-17 were the most successful of all. They carried lunar rovers to the surface, extended the duration on the lunar surface, allowing for multiple EVAs, and conducted the best science of the entire Apollo program.

That's how incremental testing is conducted to extend the performance envelop of aerospace vehicles and the knowledge of the crews to operate them. Mars Direct comes across to me as skipping too many steps, essentially like trying to land on the moon on Apollo 7 or 8. Dumb.

Sending humans to Mars without similar steps is not only a ticket to failed missions, you'll almost certainly lose at least one crew. For some strange reason, America has become so risk adverse that the loss of a space crew can threaten the entire program.

The technology for going to Mars will definitely have to be tested before sending humans on such a journey. They don't have to duplicate the full path taken by Apollo, but to ignore it completely would be foolish. Some of the technology could well be tested on the moon or on another mission, such as to an NEO. Other things, such as the landing vehicle, couldn't be tested anywhere but on Mars due to atmospheric considerations.

The key to developing a Mars program that has a chance of succeeding is to keep the number of untested elements to the lowest possible value. The basic equivalent of the CM/SM can only partially be tested in Earth orbit. That doesn't come close to matching the conditions of orbit around Mars, such as temperature diffences (remember those MO valves), radiation differences, etc. You could adequately test virtually all of the systems on an NEO mission, though. You can test most of the Mars lander systems on the moon except for the heat shield and any parachute system you might use. Life support, avionics, propulsion, thermal, electrical, and EVA systems/techniques can all be tested pretty adequately on the moon.