My own preference is for humans to go.

Robots can lead the way as our scouts. But when it comes time to go digging, exploring, researching, performing real science, humans need to be there.

Any serious exploration of space beyond the Moon means chemical rockets must be relegated to a secondary role. Even going to the Moon should be done by something besides chemical rockets.

The same alternatives always seem to enter into any discussion about what should supplant chemical rockets. To me, all the discussion is fun but to little purpose. There must be a willingness to adopt other technologies first.

If that willingness is there first and foremost within NASA, then all things become possible. Right away, we have an alternative. Nuclear rockets. VASIMIR, NERVA, Orion, some other architecture. But nuclear.

So, just as politics dictated that men should reach the Moon decades ahead of schedule, politics will also determine when men venture beyond orbit with the help of nuclear propulsion. With that first step, the solar system opens up, and is unlikely to ever be closed to us again.

I wonder, though, when that step will be taken? Four decades from now? A century from now? Two centuries? It can't happen soon enough for me, but I fear it will happen too late for most of us here to see it.