Space notions

There has been talk about a mission to an asteroid. The problem is getting there and back in a space ship no bigger than a large transit van. OK astronauts can handle this for a week on the moon mission or in orbit but for the months that it would take to get to an asteroid or mars.

OK so my solution is to reinvent the old skylab trick.

Once the upper stage has been used up, instead of discarding it the command module ( or equivalent) disconnects turns around then docs with the now empty tank. The final stage is now emptied, flushed and the pressurised. The astronauts now enter the final stage using the the command module as the life support.

Certain elements are pre-installed (electrical wiring ) but other elements are installed from the the command module ( canvas walls )- good occupational therapy. This space would be without windows and would be minimal in terms of shielding (crew might sleep in the command module behind a wall of water). So not perfect but certainly much less cramped than the command module.

On reaching the asteroid, the crew then retreat to the command module finally throw the final stage away.

Problems ? Practically no deep space shielding as mentioned and you have to use more fuel doing course corrections.