This is true - though we've got about another 4-5 billion years before that happens.

None of the Constellation architecture really pushes deep space exploration. If that's a goal you'd want to look at things like
-New novel propulsion systems (for instance solar sails) that
don't require gobs of fuel.
-Radiation protection from cosmic-rays
-Astrobiology of humans, plants and other organisms in space
over long periods
And probably a host of others. The manned space program now really isn't heading in that direction - its not even really looking much past Mars......