Bigelow Aerospace has launched some smaller scale demonstration inflatable space stations. They have a design for an 84 persons resupply Depot. It would have 8300 cubic meters of space.
Six BA 330 modules, three BA 2100 modules, nine propulsion buses with docking node and three crew capsules.
If Spacex succeeds with developing its reusable rocket and continues making upgrades to their rockets. I think a conservative expectation is that they would follow up the Merlin 1D with a Merlin 1E. Enough to increase the lift a Spacex Superheavy to 85 tons (reduced to 70-75 tons with fuel saved for powered landing to enable reusability). This could enable Spacex to launch the 2100 cubic meter inflatable modules. The other way would be for a modified inflatable module design that would fit into the largest Spacex launch rocket.
Space Exploration Technologies Corp. (SpaceX) will test its flyback booster technology during the maiden launch of its Falcon 9 1.1 rocket from Vandenberg Air Force Base in California later this year, according to the company’s Federal Aviation Administration (FAA) commercial launch license.
Spacex could launch 100 Bigelow modules for about $1 billion using two reusable Spacex Heavies over as little as one year (one launch per week).
This would be 200,000 cubic meters of volume. This would be enough for 2000 people with the same facilities per person as the Hercules resupply depot design.
Robotic and additive manufacturing could enable massive frames and massive solar power arrays
Tethers Unlimited is currently developing a revolutionary suite of technologies called “SpiderFab” to enable on-orbit fabrication ofof large spacecraft components such as antennas, solar panels, trusses, and other multifunctional structures. SpiderFab provides order-of-magnitude packing- and mass- efficiency improvements over current deployable structures and enables construction of kilometer-scale apertures within current launch vehicle capabilities, providing higher-resolution data at lower life-cycle cost.
They have received a $500,000 phase 2 NASA NIAC contract, which follows a $100,000 phase 1 contract to develop the technology.
100 of the 2100 cubic meter stations would be about $50 billion without any volume discount.
Launching with reusable rockets would be about $1 billion.
Say $10-20 billion for Spiderfab constructed solar power dish arrays and structure.
There would need to be $10-20 billion for operations.
It would be less than the cost of the international space station.
Scale of a ten thousand person colonization base would be within reach
A ten thousand person colonization space ship design is proposed with a focus on how the community and living spaces should be designed. People are assigned area with the density of the city of Seattle and standard mixed use living areas. Everyone has 50 square meters of living space. There is agricultural and other green areas.
The International space station was built with 160 modules and dozens of launches over fifteen years. It weighs 450 tons. It has about 850 cubic meters of pressurized volume and has a crew of 6.
The cost is $150 billion including 36 shuttle flights at $1.4 billion each, Russia’s $12 billion ISS budget, Europe’s $5 billion, Japan’s $5 billion, and Canada’s $2 billion. Assuming 20,000 person-days of use from 2000 to 2015 by two to six-person crews, each person-day would cost $7.5 million, less than half the inflation adjusted $19.6 million ($5.5 million before inflation) per person-day of Skylab.