1. Fuel depots. 2-17 times more stuff to the moon or other space missions. Lowering costs for GTO closer to LEO orbit costs
Boeing Propellant fuel depot
2. Lunar concrete would reduce the amount of material needed to build things on the moon by ten times.
A 50 meter telescope could be built from lunar concrete, with the mirror covered with a thin layer of aluminum. It could directly image any potential continents on planets around nearby stars with no atmosphere on the moon to distort the massive light gathering area.
3. Successful Big and cheap rockets by Spacex or others
Spacex is working achieve reusable rockets which would bring costs down to $50-100 per pound.
4. Bigelow – inflatable space stations
Bigelows planned habitable private space station
If Bigelow Aerospace can get a full size inflatable station into orbit, then they can focus farther out into space. One of the key places in Bigelow’s plan is a point about 200,000 miles (323,000 kilometers) out from Earth in the moon’s direction, where the pulls of terrestrial and lunar gravity balance each other.
Bigelow would turn that region of space, called L1, into a construction zone. Inflatable modules would be linked up with propulsion/power systems and support structures, and then the completed base would be lowered down to the moon’s surface, all in one piece.
Once the moon base has been set down, dirt would be piled on top, using a technique that Bigelow plans to start testing later this year at his Las Vegas headquarters. The moon dirt, more technically known as regolith, would serve to shield the base’s occupants from the harsh radiation hitting the lunar surface.
1-2MW Vasimr lunar cargo vehicle could transfer up to 39% of the mass from low earth orbit to the moon.
A simplified picture of the electric sail. An actual system would have 50 to 100 or more 20 kilometer wires. 100 kg spaceships could be accelerated to final speeds of 40-100 km/second. A demo version of the solar electric sail should go into space this year.
The electric sail could be used as a tug for moving things robotically to and from low earth orbit to lunar orbit or to the moon or to and from asteroids.
7.Power source breakthroughs
Nuclear power – conventional, unconventional, fusion, cold fusion
8. Tele-operation and Robotics