Critical Challenges

1. Asteroid Collisions with Earth
The probabilities and the negative consequences are higher than those for most "popular" doomsday events (pandemics, super-tsunamis, super-volcanoes, nuclear war).

2. Space-based Solar Power generation
The most "green" and open-ended sustainable way to power the Planet and in-orbit habitats and operations.

3. Space Habitats and Operations
Not necessarily for humans either. Both human and robot-agent operations such as asteroid mining and zero-G or low-G manufacturing

4. Terra-Forming
On the moon and later beyond, including Mars, the Asteroid Belt, moons of Jupiter, and Venus.

5. Exceptional Construction
A different kind of tool and toolbox is needed for building solar sails, space elevators, and starships. It all starts with getting the Mind out of the Box in which it has trapped itself.