Quote from: Impaler on 05/24/2015 04:04 amThe largest challenge seems to be volume for living space, people are going to need several cubic meters each for such a long journey. If there is an in-space propulsion vehicles then it would have no trouble accommodating the volume need through inflatables, while the lander can easily accommodate people at air-liner like densities for the brief launch and landing periods, as well as house the ECLSS and consumables.Let's put a simple, arbitrary, *conservative* curve on living space. Not precise at all, but there's no real way to be precise without testing astronauts to failure at high N. Evidence is all about what people felt was appropriate in the past subjectively. Numbers are in pressurized volume. Everyone seems to agree that there is a curve, and it has some relationship to time and crew size, though the shape varies.Hours: 1m3 survivable minimum, 3m3 comfortable, 10m3 plausible maximum benefitDays: 3m3 survivable minimum, 10m3 comfortable, 30m3 plausible maximum benefitMonths: 10m3 survivable minimum, 30m3 comfortable, 100m3 plausible maximum benefitYears: 30m3 survivable minimum, 100m3 comfortable, 300m3 plausible maximum benefitSeveral of the studies max out at 6 months (~= indefinite), but this has not been demonstrated or falsified. The last one I checked said something about 16m3 demonstrated need, 25m3 assumed margin for indefinite stay. At some point you have to factor in long-term things like the aforementioned laundry / spare clothes, and a host of other subtle things that you would find you miss only if kept in solitary confinement. Remember that this also needs to include space for spacesuits, backup spacesuits, tools, clothing, food, repair equipment, samples, sample-collecting tools, emergency gas and liquids canisters... everything.Designing to the 100m3 mark for an interim exploration mission of 25 people, and the ~25m3 mark for the eventual 100 person colony mission, is what I lean towards.
The largest challenge seems to be volume for living space, people are going to need several cubic meters each for such a long journey. If there is an in-space propulsion vehicles then it would have no trouble accommodating the volume need through inflatables, while the lander can easily accommodate people at air-liner like densities for the brief launch and landing periods, as well as house the ECLSS and consumables.
I also showed that one of our best models for extended spaceflight, the ballistic missile submarine, has at least 22m3 pressurized volume (and according to a serviceman, the real number is higher than that) per person when you take into account living space and operations space that's not devoted directly to SSBN hardware. Pressurized volume is not air space, but may be filled with gear and food - everyone apparently has their own definition of 'habitable volume'.~1.27m3 is Gemini grade accommodations. ~10.6m3 is Shuttle grade accommodations, ~120m3 is Skylab grade accommodations. The Allure of the Seas cruise ship provides around 73m3 per person internal volume at maximum occupancy, but has open decks, no ECLSS and minimal ventilation issues, and makes frequent resupply and port calls.Going another power of 3 down relative to these 'survivable minimum' spans may be borderline technically possible, but leaves no spare space for any kind of activity (the vast majority would not be air volume, but gear/food), and goes beyond the threshold for what we could expect the most stable people to tolerate - you would expect a certain amount of damaged goods on the other end of such a trip. Gemini 7 went 2 weeks and Gemini 5 went 1 week with 1.27m3 per person, to demonstrate that it was survivable... and based on what I've read of their experiences, if you put a hundred carefully screened people through that not all of them are going to come out the other end.
Except in early 1900s and earlier, the "economy class" accommodations on ships were only 5 m^3 per passenger (including hospital, etc). That is clearly possible as it was standard accommodations. I don't see why we'd pick a minimum more than that.Also keep in mind ballistic missiles are working vessels, not passenger ships. This a large portion of that per person volume is space devoted to their task, like the sonar room, etc.
BTW, I don't think departure from LEO is a good assumption. If you assume departure from LEO, ~100 day transits are likely to not be terribly practical. Depart from a high orbit, though, with propellant possibly delivered with SEP, and ~100 day trajectories become feasible.
For the longest time I wanted to loft *everything* to high Earth orbit or high Mars orbit with SEP before adding humans to the mix (skipping the Van Allen belts) with a small crew capsule. This would have saved a *lot* of IMLEO. Unfortunately, I can't discount the possibility it would give unmanned electronics problems to spend so much time in the Van Allen belts, so you revert to the much smaller bonus of lofting propellant to high orbit with SEP and sending the ~200-500T spacecraft there with chemical propulsion to refuel.
Do you have a citation for 5m3 of volume per passenger?Quote from: Robotbeat on 06/13/2015 03:41 pmBTW, I don't think departure from LEO is a good assumption. If you assume departure from LEO, ~100 day transits are likely to not be terribly practical. Depart from a high orbit, though, with propellant possibly delivered with SEP, and ~100 day trajectories become feasible.For the longest time I wanted to loft *everything* to high Earth orbit or high Mars orbit with SEP before adding humans to the mix (skipping the Van Allen belts) with a small crew capsule. This would have saved a *lot* of IMLEO. Unfortunately, I can't discount the possibility it would give unmanned electronics problems to spend so much time in the Van Allen belts, so you revert to the much smaller bonus of lofting propellant to high orbit with SEP and sending the ~200-500T spacecraft there with chemical propulsion to refuel.
Quote from: Burninate on 06/13/2015 04:14 pmDo you have a citation for 5m3 of volume per passenger?Quote from: Robotbeat on 06/13/2015 03:41 pmBTW, I don't think departure from LEO is a good assumption. If you assume departure from LEO, ~100 day transits are likely to not be terribly practical. Depart from a high orbit, though, with propellant possibly delivered with SEP, and ~100 day trajectories become feasible.For the longest time I wanted to loft *everything* to high Earth orbit or high Mars orbit with SEP before adding humans to the mix (skipping the Van Allen belts) with a small crew capsule. This would have saved a *lot* of IMLEO. Unfortunately, I can't discount the possibility it would give unmanned electronics problems to spend so much time in the Van Allen belts, so you revert to the much smaller bonus of lofting propellant to high orbit with SEP and sending the ~200-500T spacecraft there with chemical propulsion to refuel.Musk said the volume of an SUV per person. http://www.edmunds.com/ford/explorer/2015/features-specs/ The Ford Explorer SUV has an internal volume of 5 m^3 (and this is the per-person accomodations of steamships turn of the century for steerage class, including facilities like hospitals, etc... I believe I have this citation at some point, but it was likely ignored). So I generally give a range of 5-10m^3 for Musk's figure. Musk also said 50-100 people on the MCT, not straight up 100 people. So a total volume of 500m^3 seems realistic, whether 50 people and 10m^3 or 100 people and 5m3. Remember, the greater volume you assume, the less chance Musk has of making this ever work at the price he mentioned. (And we can make better use of volume in microgravity than in gravity.)And I was using high orbit in a generic sense. EML1 or EML2 are energetically basically the same as a highly elliptical Earth orbit.