Mars anyone?

Glenn says manned flights may be possible because of this, as long as you don't break The Outer Space Treaty of 1967, a Cold War relic designed to prevent a "new form of colonial competition." A summary:

First, it contains an undertaking not to place in orbit around the Earth, install on the moon or any other celestial body, or otherwise station in outer space, nuclear or any other weapons of mass destruction.

Second, it limits the use of the moon and other celestial bodies exclusively to peaceful purposes and expressly prohibits their use for establishing military bases, installation, or fortifications; testing weapons of any kind; or conducting military maneuvers.

We'll see about that.