What the report does not mention is that Congress has placed specific language in the NASA budget reauthorization bills for the past 3 years expressly forbidding the expenditure of funds on research applicable only to human missions to Mars.

One of the largest open technical issues with respect to a manned mission to Mars is EDL for a large payload. Based on the budget bills Congress has passed, NASA can't spend the money on the early research and development for these systems, because they only apply to manned Mars missions.

The failing isn't NASAs fault - its the politicians who say they support the Vision, but on the other hand, tie NASAs hands in how they can allocate funds to accomplish it.

The full report is posted on the National Academies site: http://www.nap.edu/catalog.php?record_id=12471

Hmm...the Constellation Program will give this country

1) Heavy-lift launch vehicle - the single biggest need for human Mars exploration. Any "planning" without such a launcher is a fairy tale.

2) High-speed earth entry capability - required to return cremembers to earth from a Mars mission in almost all Mars scenarios

3) Autonomous rendezvous and docking capability - required for vehicle buildup in almost all Mars scenarios, even with heavy-lift

4) High-performance, man-rated, restartable, throttlable rocket engines (LOX/LH2 and maybe LOX/Methane besides). Needed for Mars landing/liftoff.

5) Planetary surface spacesuits.

The Space Station has given us the knowledge to keep crewmembers healthy in microgravity for durations consistent with trips to/from Mars.

Certainly not a complete list for a human Mars mission, but not bad.

The article has some one saying "From the beginning there has been a pay-as-you-go assumption". It's worth noting that a few years ago this "pay-as-you-go" meant different things to different people. In one case it meant that R&D, that is very long term work, and science and aeronautics, would continue at more or less the recent purchasing power or at the least not have dramatic swings in funding levels. The remaining funds would be used by Constellation so they could "pay as you go", also taking advantage of the Shuttle shut down principally as well as any budget increases by proportion to this enterprise within NASA.

Somewhere along the way "pay-as-you-go" became "pay-us-Constellation)-(from other accounts)-as-we-go".

This works for a while. Comapnies small and large in tough times routinely cut R&D, or product development, considering these as "costs". Most have share price go up a little when such announcements are made, as investors pile on driving stock prices up, in expectation of a large divendend, a large profit that year (we found money!). Smart investors flee soon after the initial grab, knowing the companies days after that are numbered.