This is why Congress will never allow the President to line item veto. None of these programs could stand up to a super-majority vote... most wouldn't achieve a plurality if voted on the record, one at a time.
Let's assume that your conclusion is correct and that "Congress" (which you are using to refer to a select subsection of Congress) funds these programs "primarily because of pork."So what? What are you going to do with that information? What is the value of that conclusion? I'd also add that this would not make space any different than any other thing that is funded by the federal government. I'm sure that we would all be shocked--just shocked!--to discover that the biggest proponents of farm subsidies come from farm states. And the biggest proponents of building submarines come from states where submarines are built. And the biggest proponents of allowing oil drilling on federal lands tend to come from states where oil drilling is a major enterprise.
The biggest symbol of all that work was Ares V. The Yet-Another-Committee Committee determined that they did indeed need a Big Rocket, and that's what they got, sort of, years later, almost.
Just off the top of my head the blunders in early 2010 were:...-scrambling after all the controversy to come up with a new goal, which led to Obama going to KSC and saying "It's asteroids."