"Then launching 600,000 people to inhabit Mars in 100 years. Really? In the entire history of space flight, some 56 years, ~550 humans have gone into space, so about ten per year on average."
If you take the first 56 years of powered flight and average out the number of people who have flown per year, how realistic would the yearly average be compared to the number of people flying in 1966? Any number of new developments could happen over such a time period.
To throw some currently ridiculous suggestions into the mix, cheaply produced strong aerogels weighing next to nothing suitable for structural jobs, single stage to orbit "space planes" a la Reaction Engines plans, maybe something clever with high temperature superconductors.
Even rocket nozzles might be improved for all I know though we think we are pretty much at the pinnacle of nozzle design. That exhaust is coming out in a pretty chaotic fashion like water out of a hose. Maybe some bright spark will come up with materials and a design to improve the lamina flow like modern "dancing fountains" nozzles. Dunno, I'm not a physicist or materials scientist.
Biting the hand that feeds IT
