-Get Orion Vehicle and Ares Launch system launched ahead of schedule.
-Plan and execute a several month journey to a Near Earth asteroid, land on it(dock with it), explore the asteroid and take samples and etc. Good stepping point for returning to the moon and going to mars.
-Create an Orbital Tug using ION or plasma thruster using Solar panels for the electricity part of the thrust energy. More efficient, kinda like a pickup truck for space only usage.
-Create the replacement for Hubble and/or a planet finder type telescope capable of directly imaging a Jupiter sized planet and indirectly "seeing" an earth sized extra solar planet.
-Develop renewable life support systems that only require an energy input to extend resources in space.
-Work on Nuclear Fission/Fusion rocket technology that can take us to the planets in reasonable amounts of time.