The main challenge to make space colonization a reality is a relatively inexpensive method of launching objects into orbit. Even after six decades of spaceflight we still rely upon chemical rockets as the principal way to get off this planet.
What makes spaceflight expensive is the fact that it a lot of energy is required to escape Earth’s gravity. Typically a rocket contains at launch of about 80 percent of its mass of fuel/propellant and only 20 percent of actual payload.
However ScienceDaily reports that researcher at the University of Washington have developed a new type rocket that is way more efficient than current ones:
Unfortunately this type of rocket, called a rotating detonation engine, is currently only a mathematical model. And its inventors do not expect a functional prototype of this new rocket type in the near future. Also its behaviour is at this moment too unpredictable.
Though the article states that a rotating detonation engine is more efficient than current conventional rockets, I have not been able to find some actual numbers on how much. And this is important. If the theoretical saving would only be, say, five percent, we should question whether we should continue the research into this type of rocket. However, if theoretical saving would be, say, 25 or even 50 percent, that would be of great interest for any space-faring civilization.