Quote from: meekGee on 01/15/2018 03:46 amSo even under the numbers you quote (which I think are a bit optimistic), food at least competes with propellant ISRU.Which would make sense. A person at rest is a constant 100 Watt consumer I believe. Factor in the efficiency of metabolism, and the fact that you're not always at rest, and then the efficiency of the agriculture producing the food, and it adds up to near what that BFS needs, per person.I might be out of context here, but usually when people are comparing fuel ISRU to other energy usage, it is combined with the argument that solar power is sufficient, because even during dust storms you can still have plenty of power for your life support (something like 100w/person), being far less than fuel ISRU. It often comes up in discussions of solar vs nuclear.Food is a form of energy storage, so the intermittent solar power issues are not such an issue here. You could stockpile basic food calories for a decade ahead. It would be useful if your most basic crops are salvagable if there is a dust storm. I am confident there are such options.In the longer term I certainly do expect BFR fuel ISRU to become a minor part of the energy budget. It could theoretically become zero when there is enough local population growth.
So even under the numbers you quote (which I think are a bit optimistic), food at least competes with propellant ISRU.Which would make sense. A person at rest is a constant 100 Watt consumer I believe. Factor in the efficiency of metabolism, and the fact that you're not always at rest, and then the efficiency of the agriculture producing the food, and it adds up to near what that BFS needs, per person.
Did we ever create that power-on-Mars thread like we were told to?
[TBM habs]
wrt. living in tunnels: I think you are missing the point of going to Mars. SpaceX wants to settle Mars because its exciting and fun. There are other reasons but thats the primary there. If you are setting up the settlement as a bunch of tunnels, it defies the purpose. You could live in tunnels here on Earth far cheaper. Settling Mars makes only sense if a significant part of the settlement is above ground. So that you experience Mars on a daily bases. That means windows at the very least.There is no doubt that tunnels will be a big part of a Mars city. But putting too much emphasis on the tunnels is a mistake I think.
Quote from: blasphemer on 01/14/2018 06:43 pmQuote from: Lumina on 01/14/2018 06:07 pmA village-size habitat that is mostly underground, with distributed hydroponic farming based mostly on artificial light and an energy source that is mostly distributed nuclear (https://www.nasa.gov/directorates/spacetech/kilopower) Sounds great. However, single Kilopower reactor is only 1 to 10 KWe. How many MWe would be required to lets say, have enough artificial light to reliably feed a dozen people on Mars and also fill up a BFS with ISRU propellant? That seems like a lot of Kilopowers.....that's why solar is likely to be the predominant power source on Mars.
Quote from: Lumina on 01/14/2018 06:07 pmA village-size habitat that is mostly underground, with distributed hydroponic farming based mostly on artificial light and an energy source that is mostly distributed nuclear (https://www.nasa.gov/directorates/spacetech/kilopower) Sounds great. However, single Kilopower reactor is only 1 to 10 KWe. How many MWe would be required to lets say, have enough artificial light to reliably feed a dozen people on Mars and also fill up a BFS with ISRU propellant? That seems like a lot of Kilopowers..
A village-size habitat that is mostly underground, with distributed hydroponic farming based mostly on artificial light and an energy source that is mostly distributed nuclear (https://www.nasa.gov/directorates/spacetech/kilopower)
I wonder how much time scientists at Amundsen-Scott South Pole Station spend outside?
A word has been coined for places where being outside is uncomfortable and/or dangerous. The word is "uninhabitable".
In most inhabited places, outside is for portions of the year uncomfortable and/or dangerous to be in for long periods unprotected.
Quote from: speedevil on 02/13/2018 04:29 pmIn most inhabited places, outside is for portions of the year uncomfortable and/or dangerous to be in for long periods unprotected.And if those portions of the year become almost all of the year the place becomes uninhabited.
This thread is about envisioning habitats.<snip>what will their habitats look like.
there are schemes to shield areas of the surface from radiation using magnetism, but this would require large amounts of energy, i.e. a fairly large nuclear power plant.
Quote from: Dave G on 01/13/2018 07:50 pmthere are schemes to shield areas of the surface from radiation using magnetism, but this would require large amounts of energy, i.e. a fairly large nuclear power plant.Our Omaha Field configuration shields a city-region with < 80 kW.
I was sceptical at first, and thought SpaceX would dig their underground Mars base with roadheaders, but given the latest developments with The Boring Company I am coming around to the idea that SpaceX will go for a heavily modified, modular and light TBM for their Mars base construction. For sure using a Tunnel Boring Machine will greatly speed up the pace of tunnelling compared to using a roadheader. Especially if they manage to produce ISRU lining as it seems they are attempting in Los Angeles.
Quote from: LMT on 03/09/2018 03:10 pmQuote from: Dave G on 01/13/2018 07:50 pmthere are schemes to shield areas of the surface from radiation using magnetism, but this would require large amounts of energy, i.e. a fairly large nuclear power plant.Our Omaha Field configuration shields a city-region with < 80 kW. An interesting paper!I note on skimming you assume 1W/m or so cooling requirements.http://www.questthermal.com/products/wrapped-mli claims significantly lower than this, for example.ReBCO continues to improve.https://www.alibaba.com/product-detail/2-Generation-High-Temperature-Superconductor-tape_50013334401.html I find it amusing it's now off-the-shelf.
Terrestrial refrigeration requirement is roughly 1 W/m. The extremely cold martian environment eases refrigeration requirement (one easy thing on Mars), so the power requirement might be somewhere between 30 and 80 kW. This is a modest requirement, especially for a facility where some tens of MW must be generated, if only to manufacture sufficient propellant for the crew's Earth-return flights.