The Moon may not be quite as appealing as Mars, but it's still a complex and poorly understood world, with many questions still unanswered.
One of the headaches of high-tech test programmes is having to debug the test arrangements before you can start debugging the things you're trying to test.
It's true that Apollo 10's lander was overweight. Late in the craft's development, it became clear that its ballooning weight was endangering the whole mission.
Technically and financially, it might still make sense to give up on Ares I and simply write off the money spent on it, but politically, that's probably impossible.
The Apollo programme of the 1960s had some weight problems, too; in particular, the lunar lander needed some fairly drastic weight-reduction work.
On the technical side, Apollo 8 was mainly a test flight for the Saturn V and the Apollo spacecraft. The main spacecraft system that needed testing on a real lunar flight was the onboard navigation system.
Speaking of photography, while the Apollo 8 crew shot hundreds of photos, there was one that got everybody's attention: a blue-and-white Earth rising over a gray moonscape.
Foul-ups in testing are not uncommon, especially when the test setup is being tried for the first time.
In a small spacecraft, it was hard for the other two guys to sleep when the on-duty man was talking to Mission Control regularly.
Not until the space shuttle started flying did NASA concede that some astronauts didn't have to be fast-jet pilots. And at that point, sure enough, women started becoming astronauts.
Sometimes a malfunctioning test setup actually gives the tested system a chance to show what it can do in an unrehearsed emergency. During a test of an Apollo escape system in the 1960s, the escape system successfully got the capsule clear of a malfunctioning test rocket.
The demise of Constellation is not the death of a dream. It's just the end of an illusion.
The key virtue of orbital assembly is that it eliminates the tight connection between the size of the expedition and the size of the rockets used to launch it.
In the long run, it's impossible to make progress without sometimes having setbacks, although people who get lucky on their first attempt sometimes forget this.
Claiming that solid rockets are necessary for a heavy-lift launcher is obvious nonsense.
Is manned space exploration important? Yes - not least because it simply works much better than sending robots.
Rocket engines generally are simpler than jet engines, not more complicated.
It's true that Apollo 10's lander was overweight. Late in the craft's development, it became clear that its ballooning weight was endangering the whole mission.
Technically and financially, it might still make sense to give up on Ares I and simply write off the money spent on it, but politically, that's probably impossible.
The communications delays between Earth and Mars can be half an hour or more, so the people on the ground can't participate minute by minute in Mars surface activities.