Discovery News published an interview this morning with Jack Schmidt, a scientist and member of the final Apollo Moon landing. He comes out against NASA's current goal of launching a manned mission to a nearby asteroid by 2025. He argues that
an asteroid is a diversion ... If the ultimate goal is to get to Mars, you have a satellite only three days away that has a great deal of science as well as resources.
Let's set aside for the moment that it's doubtful NASA will be ready to launch a new manned mission into interplanetary space within the next twelve-ish years and think about where we should go.
If the ultimate goal is to send astronauts to Mars, there are several mission features to consider. A Martian voyage will require long periods of spaceflight, landing on and moving around the surface, and escaping Mars' gravity well to return home. Which medium-term target will help us prepare for these challenges? Both, it turns out.
Because the Moon is much larger than most asteroids, it'd be a more realistic dry run for landing on and blasting off of Mars (this is expensive- one reason people suggest landing on a lighter asteroid). As Schmidt notes, though, the Moon is only three days away. Protecting the first visitors to the red planet, both physically and mentally, on their multi-month journey may prove to be the most challenging part of the mission. An asteroid is almost certainly farther away than the Moon, and would provide us with valuable experience in long-duration spaceflight. Some of this work is being done at the International Space Station (in fact, a Russian cosmonaut and an American astronaut are preparing to become the first humans to spend a year in space starting in 2015), but can this really prepare astronauts for the psychological toll of interplanetary space? No one knows.
So if both missions would help us towards our goal of one day visiting Mars, how should we choose? This is where an asteroid mission gains a bit of an edge in my estimation. One of NASA's core goals is to further space exploration, and exploration, by definition, means visiting places we've never been before. We've been to the Moon - let's stretch humanity's reach a bit and stick our heads out past the Earth system. I understand why a former Moon-walker would want us to return, and his reasons are undoubtedly valid. But just as I'd rather see a mission to Uranus before another Mars rover, I'd rather see us visit another member of the solar system before returning to the Moon - just as I suspect Jack Schmidt pushed for us to leave Earth-orbit and head to the Moon.
Source: Discovery News