I put it up here because I want to draw attention to part of what he said in reference to the Project Rover.
There has been opposition to nuclear thermal rockets launching from the Earth. But what if you launched it from the moon instead? You could obtain plenty of thorium for a LFTR type reactor that would supply the energy necessary for propulsion to far off regions of space, such as Mars.
There is a known location near the lunar north pole which may be combined with the water which may also be obtained, which would greatly diminish the amount of matter necessary to be lifted off the Earth's surface for such a journey.
A thorium powered rocket may even be able to launch directly from the lunar surface. It may be able to land as well. Should that be the case, it would not be necessary to have it land anywhere on Earth, or involve the Earth's biosphere at all. That should relieve opposition to the proposition to the use of nuclear thermal rockets.