It has been the prevailing wisdom up until now that for NASA to successfully implement a Moon or Mars mission or other long term manned mission it would need to have heavy launch capability.  The latest study conducted by the Augustine Panel suggests that a much more economical and sustainable model could be built on the use of smaller commercial launch vehicles with Fuel Depot launches.

"This architecture encourages the exploration of the moon to be conducted not in single, disconnected missions, but in a continuous process which builds orbital and surface resources year by year. The architecture and vehicles themselves are directly applicable to Near Earth Object and Mars exploration and the establishment of a functioning depot at Earth-moon L2 provides a gateway for future high-mass spacecraft venturing to the rest of the solar system."

http://www.popularmechanics.com/science/air_space/4330793.html

Sounds very reasonable.  Especially with all the private space programs underway right now.