While it's fair to say that NASA has a case of 'mission creep' (complete with the usual 'budget creep'), zeroing out space exploration is not a good idea.
Some things only the FedGov can do--and this is one of them, if you intend to keep the US in first place..........
Canceling Constellation could lead to thousands of layoffs at some of America's biggest aerospace contractors, including Lockheed Martin, the Boeing Co. and ATK. Such job losses are among the factors behind congressional opposition to the cancellation. Armstrong and his fellow astronauts emphasize the bigger implications, however, and say in their letter that the decision would put the nation on a "long downhill slide to mediocrity."
The letter notes that the U.S. space effort will be dependent for years to come on the Russians for transport to the International Space Station, at a cost of more than $50 million per seat.
"For the United States, the leading spacefaring nation for nearly half a century, to be without carriage to low Earth orbit and with no human exploration capability to go beyond Earth orbit for an indeterminate time into the future, destines our nation to become one of second- or even third-rate stature," they said in the letter.
Couldn't say it better.
Interesting that the astronauts identify Obama's basic operating philosophy: 'putting the nation on a long downhill slide to mediocrity.'