Manned spaceflight has lost its glamour - understandably so, because it hardly seems inspiring, 40 years after Apollo, for astronauts merely to circle the Earth in the space shuttle and the International Space Station.
I worked on all of the Apollo manned missions and a couple of Apollo unmanned missions.
Research into manned spaceflight is shifting from low-Earth orbit to destinations much further away, like Mars and the asteroid belt. But society will have to invent many new technologies before it can plausibly send people to those distances.
NASA is doing nothing but development. They're not doing research in manned spaceflight at all and I see no reason for them to do that because we already know that it will work and we already know exactly how it will work.
We collectively have a special place in our heart for the manned space flight program - Apollo nostalgia is one element, but that is only part of it. American culture worships explorers - look at the fame of Lewis and Clark, for example. The American people want to think of themselves as supporting exploration.
The practical case for manned spacef light gets ever-weaker with each advance in robots and miniaturisation - indeed, as a scientist or practical man, I see little purpose in sending people into space at all. But as a human being, I'm an enthusiast for manned missions.
I want manned spaceflight, not just back to the Moon, but beyond that. And I want my daughters and my son to have their own July 20, 1969, to remember. Apollo 11 didn't give us wings; it only showed us how far the wings we had would take us.
There were about six years when there was not one American who went into space. We shouldn't do that again.
For the new century, back to the moon, back to the future and this time back to stay. And then a journey into tomorrow, a journey to another planet, a manned mission to Mars.
Having a diverse suite of U.S.-manned spaceflight systems to access space is inherently robust.
It would be sad if the expertise built up during the 40 years of the U.S. and Russian manned programmes were allowed to dissipate. But abandoning the shuttle, and committing to new launch vehicles and propulsion systems, is actually a prerequisite for a vibrant manned programme.
