This highlights one of the problems with the SH/SS paradigm: the large refueling needs and ISRU requirement are a fair-sized impediment in the beginning. When Mars Colonial Transport was first announced, I visualized a 12 meter diameter, 3-stage vehicle that could put 450 metric tons in LEO, which was a fully fueled upper stage/spaceship that could land on Mars and return on a single load of fuel (no ISRU required). That would have facilitated true exploration. Crews could go to Mars and look for a colony site. The plan was downsized a couple of times, to today’s 9 meter refueling version whose main feature is, it can fly from existing ground infrastructure. That’s no small thing either.
This highlights one of the problems with the SH/SS paradigm: the large refueling needs and ISRU requirement are a fair-sized impediment in the beginning. When Mars Colonial Transport was first announced, I visualized a 12 meter diameter, 3-stage vehicle that could put 450 metric tons in LEO, which was a fully fueled upper stage/spaceship that could land on Mars and return on a single load of fuel (no ISRU required). That would have facilitated true exploration. Crews could go to Mars and look for a colony site. The plan was downsized a couple of times, to today’s 9 meter refueling version whose main feature is, it can fly from existing ground infrastructure. That’s no small thing either.