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#60 by Rocket Science on 26 Mar, 2012 22:07
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That is nice and tidy. The public could understand that!If we go to Phobos, for example, the public is going to ask why we didn’t land on Mars instead. We can’t use “Mars is hard” and expect them to understand and buy it. They would see it as going on a road trip across country to see the Empire State Building in NYC and not going up to the top when you got there.
The answer is that NASA is building the spacestation on Phobos. There are plenty of towns where the railway stops outside the town and you get a taxi to your hotel. The large inter-planetary spacecraft are not designed to operate in an atmosphere and it would be too expensive to make them.
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#61 by Robotbeat on 26 Mar, 2012 22:09
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It's a significantly different environment. A short-stay Mars mission would spend the vast majority of the time in transit or in orbit. The lander would have to be very different (Mars one would need to take aerodynamics into consideration, lunar one wouldn't), so unless you designed the lunar lander to Martian conditions from the get-go (a lot more expensive), you'd have to do the designing twice, and the lunar one would still be quite suboptimal.WE don't know, but an outpost of some kind on the Moon where we could put astronauts for 6 months or more at a time, could tell us some of that. A VERY useful bit of info for Mars missions, or other long duration mission if there's any potential for considering generating artificial gravity.
And such a Moon base operated for ten years may very well cost the same as the first Mars mission.
After such an expensive, but sustained campaign on the Moon, surely this would provide experience to reduce the costof the subsequent Mars mission?
cheers, Martin
The Moon would have to deal with a uniquely brutal sort of dust contamination for long-term missions (Apollo showed that short-term is not a huge issue, though annoying) whereas Mars's dust is pretty similar to certain terrestrial dust because both are formed primarily through wind processes.
ISRU would be vastly different between the two celestial bodies, with Mars ISRU being a lot easier since you can just suck in the Martian atmosphere and avoid having to do any regolith processing. And the Moon still doesn't give you experience with the sort of autonomy from ground control needed for a Mars mission (though I suppose that could be done artificially).
I don't see any areas which show that a decade of living on the Moon would give us a huge advantage in cost for a subsequent initial Mars mission beyond what can be achieved on a place like ISS for a lot less and a lot sooner. I suppose if you have a flexible enough Mars lander (i.e. not well optimized to Mars), you could test it on the Moon first, but that doesn't seem to justify a full lunar base with all the logistics and cost that'd entail.
Another issue is that a lunar base would have higher radiation doses than a Martian one (at lower altitudes), so astronauts on an EVA would always have to fear a big solar particle event, while astronauts on Mars would have the advantage of a significant atmosphere that filters out solar particle events to non-life-threatening levels. Lunar structures would also have to contend with micrometeorites, something that's not an issue on Mars because of Mars's atmosphere. Also, the Moon has much larger temperature swings because of its utter lack of atmosphere. -
#62 by Khadgars on 26 Mar, 2012 22:43
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To me it seems pretty clear why thus far it's all been about the capabilities and not really the mission and that's about jobs and maintaining support in Congress.
That doesn't mean they don't have their own internal road maps (as we've seen from Chris) or a grand scheme for the entire program, but now is not the time to reveal that. -
#63 by RocketmanUS on 31 Mar, 2012 20:38
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One year and three year time on the moon. Six man team , two return to Earth after one year the other four return after three years.
And such a Moon base operated for ten years may very well cost the same as the first Mars mission.There's no such thing as extreme low gravity. It's either low or it's not.
As far as long term goes, Russian cosmonauts have been in zero-g for more than a year at a time. They were weak when they returned to earth but otherwise healthy. They recovered their strength as they re-acclimated to full-g.
WEll, we can easily test prolong exposure to zero-g on the ISS. We can put a guy up there for ever a year if we want. and remove him if there's any health problems while he's there. Easy enough.
What we can't test out is prolonged exposure to "low" gravity, such as the Moon's, Mars, or some sort of artificial gravity during a long term mission. We don't know if the body's reaction to gravities bewteen zero and 1g is linear, or something else. It could be that exposure to 1/6 gravity woudl allow a person to greatly reduce their muscle and bone loss, especially if they where body weights to make themselvses heavier. (something that can't be done is zero-g, no matter your mass, if there's no graivty, there is no resistance on the body). Or 1/6 gravity might simply be a little less bone and muscle loss than zero-g. 1/2 gravity being 1/2 muscle and bone loss, etc.
WE don't know, but an outpost of some kind on the Moon where we could put astronauts for 6 months or more at a time, could tell us some of that. A VERY useful bit of info for Mars missions, or other long duration mission if there's any potential for considering generating artificial gravity.
The one year team would help to know if a NEO or Mars mission could use a 1/6 artificial gravity instead of 1g. Should be easier to make a 1/6 artificial gravity instead of the 1g space craft. If the crew were better off with 1/6 instead of micro gravity then that could benefit transit times greater than six months ( stronger once back in gravity ), whether for NEA or Mars.. We want our crews to be strong and ready once they get to the destination(s).
Three year team to help determine if we can live of world, many factors involved.
NEO missions are more for beyond Mars missions than for Mars mission(s).
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#64 by Warren Platts on 01 Apr, 2012 18:48
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WE don't know, but an outpost of some kind on the Moon where we could put astronauts for 6 months or more at a time, could tell us some of that. A VERY useful bit of info for Mars missions, or other long duration mission if there's any potential for considering generating artificial gravity.
After such an expensive, but sustained campaign on the Moon, surely this would provide experience to reduce the cost of the subsequent Mars mission?
cheers, Martin
I agree with the above.Quote from: RobotbeatAnd such a Moon base operated for ten years may very well cost the same as the first Mars mission.
Bingo. We could have a vibrant, permanently manned Lunar station for the cost of a single, short-stay Mars mission.QuoteIt's a significantly different environment.
Not really.QuoteA short-stay Mars mission would spend the vast majority of the time in transit or in orbit.
So why bother?
QuoteThe lander would have to be very different (Mars one would need to take aerodynamics into consideration, lunar one wouldn't), so unless you designed the lunar lander to Martian conditions from the get-go (a lot more expensive), you'd have to do the designing twice, and the lunar one would still be quite suboptimal.
Not necessarily true: e.g., take the ULA DTAL Lunar lander: according to Zegler and Kutter, it's cigar shape is preadapted to endoatmospheric flights, and a Mars lander would be a straightforward upgrade of the ACES-41 version. Upgrading the lander would simply be a matter of stretching the tank to the ACES-71 version, and maybe swapping out the RL-10's with RL-60's. You'll want to make the skin out of a heat resistant material like Inconel nickel alloy. That's pretty much about it. A true 2 for 1.QuoteThe Moon would have to deal with a uniquely brutal sort of dust contamination for long-term missions (Apollo showed that short-term is not a huge issue, though annoying) whereas Mars's dust is pretty similar to certain terrestrial dust because both are formed primarily through wind processes.
Brutal?
That's funny! At least Moon dust isn't poisoned with loads of perchlorates (forgot about Phoenix already, eh?). Yeah, you don't want to be breathing Moon dust, but believe me, you don't want to breath Mars dust either. There are Earth environments where the dust is as bad (mining, asbestos removal, air drilling). But they'll be wearing "spacesuits" with self-contained breathing, so it won't be a health issue. Setup a shower and vacuum system in the airlock. You'll have to do that at both Moon and Mars anyway. Another 2 for 1. Mars has no advantage in terms of nastiness of the dirt.
Indeed, I don't see how you'll be able grow crops in a greenhouse on Mars. I guess it'd have to be all hydroponic. On the Moon, however, once fertilized with compost, Lunar soil would make a great growing medium; it would be like a fresh volcanic soil on Earth. Plants will love it.QuoteISRU would be vastly different between the two celestial bodies, with Mars ISRU being a lot easier since you can just suck in the Martian atmosphere and avoid having to do any regolith processing.
Yeah, but you got to put in on the critical path. And so you better hope it works for two years before the humans land. And then you only get substandard Isp propellant for your efforts. Zubrin wanted to import LH2 from Earth....
On the other hand, if you did develop a Lunar ISRU capability, then transferring that technology to Mars would be a piece of cake. This is especially important if you want a permanently manned station on Mars. You'll want to be able mine your own water out of the Martian regolith. Developing this capability as part of the Lunar program means that the Mars program won't have to spend money developing this capability. Another 2 for 1.QuoteAnd the Moon still doesn't give you experience with the sort of autonomy from ground control needed for a Mars mission (though I suppose that could be done artificially).
Yes.QuoteI don't see any areas which show that a decade of living on the Moon would give us a huge advantage in cost for a subsequent initial Mars mission beyond what can be achieved on a place like ISS for a lot less and a lot sooner.
Let's see: (1) Lander; (2) dust mitigation; (3) regolith processing; (4) gravity in 1/6 g; (5) abundant Lunar propellant; (6) propellant depots; (7) reusable MTV's built out of leftover Lunar 3rd stagesQuoteI suppose if you have a flexible enough Mars lander (i.e. not well optimized to Mars), you could test it on the Moon first, but that doesn't seem to justify a full lunar base with all the logistics and cost that'd entail.
The main value of a Lunar station is that it keeps US skin in the Moon game. This has nothing to do with Mars.
Moreover, an optimal Mars lander would be fully propulsive. This would give it the capability to make a pinpoint landing anywhere on Mars surface without having to worry about the atmospheric density. Yeah sure it requires more propellant than landing with parachutes that can fail and hefty heat shields, but it's a lot easier to design, and the extra propellant required can be imported from the Moon.QuoteAnother issue is that a lunar base would have higher radiation doses than a Martian one (at lower altitudes), so astronauts on an EVA would always have to fear a big solar particle event, while astronauts on Mars would have the advantage of a significant atmosphere that filters out solar particle events to non-life-threatening levels.
Not an issue. Moon will have radiation protected habitats. Early warning of solar flares will be provided by a satellites at the Earth Sun L-1 point.QuoteLunar structures would also have to contend with micrometeorites, something that's not an issue on Mars because of Mars's atmosphere.
Well, after 50 years of spaceflight, there has yet to be a loss of a vehicle or human life to a micrometeorite. Evidently, there's no crisis there.QuoteAlso, the Moon has much larger temperature swings because of its utter lack of atmosphere.
Wrong. At permanently illuminated plateaus in the polar regions, the ambient temperature is a balmy -50 degrees plus or minus 10 degrees. Arguably better than South Pole Station in the winter. -
#65 by RocketmanUS on 24 Oct, 2012 03:16
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For an asteroid can the DSH follow behind the asteroid and anchor to it?
Could it then be possible to use the line between the two as a space elevator between the two?
If so how long would the line have to be? -
#66 by A_M_Swallow on 24 Oct, 2012 04:13
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For an asteroid can the DSH follow behind the asteroid and anchor to it?
Could it then be possible to use the line between the two as a space elevator between the two?
If so how long would the line have to be?
The asteroid would have to be solid. A tether would just cut through a rouble asteroid releasing the DSH. -
#67 by Archibald on 24 Oct, 2012 08:19
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That is nice and tidy. The public could understand that!If we go to Phobos, for example, the public is going to ask why we didn’t land on Mars instead. We can’t use “Mars is hard” and expect them to understand and buy it. They would see it as going on a road trip across country to see the Empire State Building in NYC and not going up to the top when you got there.
The answer is that NASA is building the spacestation on Phobos. There are plenty of towns where the railway stops outside the town and you get a taxi to your hotel. The large inter-planetary spacecraft are not designed to operate in an atmosphere and it would be too expensive to make them.
That, plus the Most Stunning Picture Ever: astronauts planting the flag with monster Mars as background, a huge ocher globe masking half of the sky.
That's funny! At least Moon dust isn't poisoned with loads of perchlorates (forgot about Phoenix already, eh?). Yeah, you don't want to be breathing Moon dust, but believe me, you don't want to breath Mars dust either. There are Earth environments where the dust is as bad (mining, asbestos removal, air drilling). But they'll be wearing "spacesuits" with self-contained breathing, so it won't be a health issue. Setup a shower and vacuum system in the airlock. You'll have to do that at both Moon and Mars anyway. Another 2 for 1. Mars has no advantage in terms of nastiness of the dirt.