Absolutely, but what is the leap from building and sustaining a space station, and simply going a bit further out. O2 and Food? Fuel? What is it that makes it impossible in your opinion?
The hardest thing about it all imo, is the landing and taking back off, but I've seen the lunar landers in person at Cape Canaveral and understand how they work, and personally, I believe it.
We have upgraded from Rockets to a Space Shuttle, which can hook upto other shuttlers or stations in space and transport etc. But yes the propulsion of it is the same premise. Launching a rocket/shuttle on earth is definately a difficult challenge, but with gravity on the moon being what it is, I believe the lunar landers are definately feasable for "interplanetarty travel".