From [Larson, 1999, page 404] we can see that a mission of under 1 day only needs
about 1 cubic meter per person. In [ibid, page 403] they have the following
formula for estimating the mass of a crewed vehicle in Kg:
592 * (number of crew * mission duration (days) * pressurized volume (m^3)) ^ 0.346
For crew of 11 people and a volume of 11 cubic meters this comes to 3111 Kg.
For a rugged and reusable heat shield (possibly with transpiration) we will add 25% to this amount, or 778 Kg. An ablative heat shield can be done with only 15%.
From [ibid, page For a reusable (and very safe) heat shield it is probably more than 15%, say 25%. Then we are at 3889 Kg. Still enough room for some grapple attachment and keeping under our 4,000 kg design point. They say this does not include a heat shield or any mission specific stuff, just living space and life support. They estimate that an ablative heatshield is 15% additional mass. Also, this is based on historical data. Current tech should be better than historical average really. So we may well get more than 11 people in 4,000 Kg. We feel good saying 10 passengers and 1 employee, but that it has a good chance of being more.
If a designer wanted to have enough shielding for flares it would make sense to have the shielding mass transfered from the LEO tether to the capsule after it is picked up and returned to the LEO tether for the next capsule when it is about to reenter. This would require a stronger tether, but not a stronger rocket or more solar power. So it could be done without too much penalty.
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