Quote from: mrmandias on 11/27/2012 10:20 pmMusk keeps mentioning public-private partnerships to settle Mars. I wonder if his $500,000 figure assumes that development costs are paid by government customers so that the passenger is only having to pay manufacturing and operation costs. How much would a 747 cost if Boeing had developed it for 'free'?Based on other information he's said I doubt it. He talks about $500,000 being the price at which someone could sell everything they have and move (ala the english colonists). Those wouldn't be government passengers.
Musk keeps mentioning public-private partnerships to settle Mars. I wonder if his $500,000 figure assumes that development costs are paid by government customers so that the passenger is only having to pay manufacturing and operation costs. How much would a 747 cost if Boeing had developed it for 'free'?
Quote from: A_M_Swallow on 11/27/2012 03:32 am>A colony able to produce its own food, water, clothing, transport, energy, furniture and buildings is going to be very sophisticated. I suspect that level of self reliance will not be available until towards the end.ISRU doesn't just mean using what's thrre, but finding multiple uses for what you bring with you. Look to the past, as in our ancestors handcrafts.Water: subsurface & recyclngFood: grow your own, see greenhouseClothing: growing your own food & other plants are a great source of cellulose fibers. See spinning wheel & looms. Worked for great-granny.Furniture: thicker plant stems are easily made into wicker. Wicker makes very durable furniture.Buildings: look to the opal miners of Australia who dig their shelters underground as they mine. Lots of other ways to do it as well.
>A colony able to produce its own food, water, clothing, transport, energy, furniture and buildings is going to be very sophisticated. I suspect that level of self reliance will not be available until towards the end.
If we assume that the average stay on Mars is 10 years (some will stay permanently, others only a couple of years), then using 150 person transfer habs in low energy trajectories about 1000 are needed. If it takes 20 years to build up, then the production rate is 50/year or 1/week. This is about twice that of the 747-8. Although a high rate for large aerospace structures it is nowhere near car production levels. If using high energy (say 2 weeks one way on average) only about 40 transfer habs are needed. I know of no current technology which could give such high speed trajectories and even if such a technology is developed the cost of the energy for the trip would be high.
Quote from: MikeAtkinson on 11/28/2012 06:05 amIf we assume that the average stay on Mars is 10 years (some will stay permanently, others only a couple of years), then using 150 person transfer habs in low energy trajectories about 1000 are needed. If it takes 20 years to build up, then the production rate is 50/year or 1/week. This is about twice that of the 747-8. Although a high rate for large aerospace structures it is nowhere near car production levels. If using high energy (say 2 weeks one way on average) only about 40 transfer habs are needed. I know of no current technology which could give such high speed trajectories and even if such a technology is developed the cost of the energy for the trip would be high.One per week is a lot. But what if instead of 150 people per transfer hab, it's more like 4 or 5? And what if the build-up is much faster, like ten years?
Quote from: Robotbeat on 11/28/2012 04:57 pmQuote from: MikeAtkinson on 11/28/2012 06:05 amIf we assume that the average stay on Mars is 10 years (some will stay permanently, others only a couple of years), then using 150 person transfer habs in low energy trajectories about 1000 are needed. If it takes 20 years to build up, then the production rate is 50/year or 1/week. This is about twice that of the 747-8. Although a high rate for large aerospace structures it is nowhere near car production levels. If using high energy (say 2 weeks one way on average) only about 40 transfer habs are needed. I know of no current technology which could give such high speed trajectories and even if such a technology is developed the cost of the energy for the trip would be high.One per week is a lot. But what if instead of 150 people per transfer hab, it's more like 4 or 5? And what if the build-up is much faster, like ten years? I'm assuming a professional crew of 8 will be needed and that no more than 20 passengers per crew are practical. Major systems will include, power, heat removal, air replenishment and distribution, water recycling and distribution, lighting, comms, data networks, secondary propulsion, exercise and entertainment, safety, emergency response, airlocks, docking ports and many others. Then there are the more domestic side (cooking, cleaning, washing, etc.).In general I think it likely that larger sizes will be more efficient. Production rates for a 150 person hab would be large enough that there will be few extra gains from going to 30x the rate for 5 person habs.I agree that reusable rocket stages that do not travel with the hab might be a possible way forward. An alternative might be some form of beamed power for propulsion with power stations at Earth and Mars.
what if instead of 150 people per transfer hab...And what if the build-up is much faster, like ten years? That's 60 per week, much closer to car production numbers. ...possible to make an RV-sized pressure vessel with simple RCS (perhaps cold/warm gas), simple ECLSS (not recycling, just scrubbing CO2 from a reusable scurbber and adding O2 from a liquid oxygen tank, possibly recycling water or using electrolysis to get oxygen from water for simpler storage), some body-mounted solar panels, docking port, etc? Can it be done on that sort of scale, equivalent almost to luxury car production runs? For maybe $5-10 million or less a piece?It doesn't seem /physically/ impossible, and conceivably if done with enough automation and with the development/engineering costs spread over thousands of these units, maybe it could be done economically, if the demand were there.
But this is such far-fetched talk our ability to guess the future is really limited.We're probably in "advanced topic" land here.
Agree. Maybe better to consider what a (sustainable over X years, Y years into the future) Mars colonization effort might look like, and the ground rules & assumptions, or the technology advances required to achieve a price point if $Z/person/Mars-yr.
Quote from: joek on 11/29/2012 02:55 amAgree. Maybe better to consider what a (sustainable over X years, Y years into the future) Mars colonization effort might look like, and the ground rules & assumptions, or the technology advances required to achieve a price point if $Z/person/Mars-yr.The funny thing about a colony on Mars: There are no half-steps imo. To make it big enough to be successful, you need to do it on a huge scale. Otherwise you're talking about unbearably expensive per person prices. The only way to possibly realize the thread title's claim, is to go big. Giant reusable BFR's that are mass produced and use the cheapest fuel(s) possible. Though I might be missing what you are getting at. Feel free to elaborate on your post with some specifics or claims. Then there's something more concrete to discuss.
Beamed propulsion makes no sense. Just go with solar. Seriously, people who advocate beamed power for use when solar power is available constantly (unlike the Earth's surface) are severely under-estimating how good solar power is.
Quote from: Robotbeat on 11/28/2012 06:12 pmBeamed propulsion makes no sense. Just go with solar. Seriously, people who advocate beamed power for use when solar power is available constantly (unlike the Earth's surface) are severely under-estimating how good solar power is.For high energy trajectories (2 weeks transit) the power required is in the GW. The several km2 needed for solar becomes unwieldy at those power levels (imagine several manoeuvering [British spelling] around a spaceport). Beamed power is a possibility for solving that.
But suppose instead you had only 10mT of cargo? That'd mean "only" 100MW is needed, for a much smaller solar array. Giving power requirements without mass is meaningless.
Quote from: Robotbeat on 11/29/2012 06:23 pmBut suppose instead you had only 10mT of cargo? That'd mean "only" 100MW is needed, for a much smaller solar array. Giving power requirements without mass is meaningless.10 tonnes for 150 people? No way!I assumed a slightly smaller volume and reduced supplies when I came up with the several GW estimate. Put it another way the 39 days to Mars using VISIMR was widely rejected when Ad Astra mooted the idea, because of the insanely optimistic specific power. Reducing down from 39 days to 14 days takes ~(39/14)^2 (=7.76) as great a specific power.
That's about right.But that's a very high number for beamed power propulsion as well!
I agree that reusable rocket stages that do not travel with the hab might be a possible way forward. An alternative might be some form of beamed power for propulsion with power stations at Earth and Mars.
For high energy trajectories (2 weeks transit) the power required is in the GW. The several km2 needed for solar becomes unwieldy at those power levels (imagine several manoeuvering [British spelling] around a spaceport). Beamed power is a possibility for solving that.