The one thing that keeps bothering me is the question of power.What's needed is an estimate of consumption based on the colony plans, a power system concept and design, and then an estimae of mass and manpower that passes a sanity check.Just saying "solar" or "nuclear" is not enough, and SpaceX hasn't yet anything significant about it.-----ABCD: Always Be Counting Down
I don't think SX have released any estimates for the settlement.
we’ll need to make about 1000 tons of propellant on Mars over a two-year cycle; bring it back; and that’s a tall order. You need about half a megawatt of energy to <inaudible> that much propellant <inaudible>
So if you’re taking it to Mars, it’s more efficient to ship reactors than it is to ship solar; it’s just that nobody’s really developed a space reactor yet. We’re working with NASA on that, and hopefully they’ll get funding to develop that. They’ve got a program called kilopower going that’s like, ten thousand watts, a 10 kilowatt reactor. We need a megawatt, but you know, you need to start somewhere.Eventually, the right way to have power on Mars is fission, but initially, it’ll probably be solar. But in order to get the rockets back, we need a lot of power there to make propellant.
QuoteMueller: we’ll need to make about 1000 tons of propellant on Mars over a two-year cycle; bring it back; and that’s a tall order. You need about half a megawatt of energy to <inaudible> that much propellant <inaudible>
Mueller: we’ll need to make about 1000 tons of propellant on Mars over a two-year cycle; bring it back; and that’s a tall order. You need about half a megawatt of energy to <inaudible> that much propellant <inaudible>
Quote from: john smith 19 on 04/01/2018 09:49 amWrong. The equivalent to having the same radiation protection on Earth is about a 3metre layer of regolith. I would also like a source for this. Earth atmosphere has mass of 10 tonnes per square meter. Seems to me like equivalent mass of regolith would be significantly thicker than 3 meters. Also, this:
Wrong. The equivalent to having the same radiation protection on Earth is about a 3metre layer of regolith.
Historical estimates from various groups (which IIRC appeared on the Mars life support or Mars gardening threads) had figures of 6-60Kw/person/day with 60Kw being the number for LED lit greenhouses.
Quote from: Robotbeat on 04/01/2018 05:02 pmPresentations on radiation on Mars have been given for decades, the situation has not changed much except that Mars Curiosity has validated that surface radiation levels are much less than deep space and solar events are effectively neutralized (compared to deep space).Please post a source. Mars has very weak magnetic field and very thin atmosphere. It should therefore receive almost half of deep space cosmic ray dose (like 200-300 mSv per year, other half shielded by the planet itself) and also most of solar flare doses. Not an issue if you only spend a dozen hours per week outside, but more than that and it becomes a serious concern, especially for actual colonists who will hopefully live for many years and decades on the planet, instead of year long missions.
Presentations on radiation on Mars have been given for decades, the situation has not changed much except that Mars Curiosity has validated that surface radiation levels are much less than deep space and solar events are effectively neutralized (compared to deep space).
The planet shields half the radiation, and the atmosphere (although "thin") is about 40 grams/cm^2 thick, which dramatically attenuates solar flares and also reduces dosage of GCRs somewhat. It's like a foot or two of regolith.
Quote from: Robotbeat on 04/01/2018 07:24 pmThe planet shields half the radiation, and the atmosphere (although "thin") is about 40 grams/cm^2 thick, which dramatically attenuates solar flares and also reduces dosage of GCRs somewhat. It's like a foot or two of regolith.But isnt low amount of shielding generally even worse that nothing when it comes to GCRs due to secondary radiation? Of course it may depend on exact shielding mass and elemental composition...
Shield the planet. One of NASAs ideas is a ~3 Tesla dipole placed at Sun-Mars L1. 3 Tesla is about the power of a modern medical CT scanner. PhysOrg...Presentation video, this starts at 1:36:00https://livestream.com/viewnow/vision2050/videos/150701155
Shield the planet. One of NASAs ideas is a ~1-2 Tesla dipole placed at Sun-Mars L1. 1.5-3 Tesla is about the field strength of a modern medical CT scanner. PhysOrg...Presentation video, this starts at 1:36:00https://livestream.com/viewnow/vision2050/videos/150701155
And to your point 3T scanners aren’t even state of the art. 5T and 7T scanners are being used in research hospitals. They aren’t used routinely mostly because their greater expense isn’t worth it for routine clinical needs and also because those field strengths cause disorientation to patients that usually require sedation.
>You mean an MR scanner. CT scanners do not generate magnetic fields. And to your point 3T scanners aren’t even state of the art. 5T and 7T scanners are being used in research hospitals. They aren’t used routinely mostly because their greater expense isn’t worth it for routine clinical needs and also because those field strengths cause disorientation to patients that usually require sedation.
If the plan is colonization then near term could be handled otherwise.I also wonder about a magnetic 'mesh constellation' akin to StarLink with overlapping zones of influence.
Quote from: docmordrid on 04/01/2018 07:57 pmIf the plan is colonization then near term could be handled otherwise.I also wonder about a magnetic 'mesh constellation' akin to StarLink with overlapping zones of influence.Just put superconducting cables around the equator on the surface.
Quote from: Robotbeat on 04/01/2018 08:14 pmQuote from: docmordrid on 04/01/2018 07:57 pmIf the plan is colonization then near term could be handled otherwise.I also wonder about a magnetic 'mesh constellation' akin to StarLink with overlapping zones of influence.Just put superconducting cables around the equator on the surface.You get very, very large currents flowing in the core, which act to cancel your imposed field essentially 'forever'.
You get very, very large currents flowing in the core, which act to cancel your imposed field essentially 'forever'.