But energy to get there isn’t the whole story either. There is also the supplies you would have to carry (assuming you mean a manned mission), and extra radiation shielding.
If you aren’t talking about a manned mission, then it’s more of an apples to oranges comparison, since I think a manned lunar base is what was being discussed.
I’d been just lurking in this thread, but personally I think finding water on the moon will be an important breakthrough, and will allow for more extensive manned exploration and possibly a permanent research station there. It will be a critical step before we (hopefully in my lifetime) take the next step to Mars.
If they’re anywhere near earth orbit, such watery asteroids tend to be called comets.
Water sublimes rapidly when exposed to the sun of the inner solar system, which is why NASA looked for ice in the cold trap of the permanently dark lunar pole.
If you look at that link, some asteroids are about "half’ as hard to get to as the moon. You can carry plenty of supplies and still come out way ahead.
Also, I “think” that chart I linked too doesnt even consider the energy required to land AND take off of the lunar or martian surface. If thats the case its WAY WAY easier to go to an asteroid. If an orbital mechanics expert could set me straight on that point I’d appreciate it.
Why build a base in a harder to reach desert when you can build one on a tropical island instead ?
Not if its a chemically bound substance like a hydrate.
Remember, the moon has been** twice **baked, which is why its dry as hell.
And its not so much WATER you really want, its hydrogen and compounds containing hydrogen you want. Oxygen is found easily bound up with many substances.
There is a reasonable chance a reasonable number of those asteroids are “dryed out comets”, which are barely dried as opposed to twice baked and my semi WAG is those would still have WAY more easily extractable hydrogen and oxygen than the moon.
Because it’s not harder to get to the moon than to an asteroid. It takes approximately 3 days to get to the moon…it takes weeks or months to get to the nearest asteroid AFAIK. That’s weeks or months where you’d need to provide food, water, energy, and radiation shielding for the crew.
Looking at the chart you provided, it seems to be merely talking about energy requirements and Delta-V, which is all well and good for an unmanned probe. But for a manned mission the duration is a key factor…and, intuitively, 3 days is less than weeks or months, thus you need to take less with you to get there (and back).
You will need radiation shielding anywhere outside of Earth’s magnetosphere. Certainly you can burrow into the Lunar regolith, but you can also just place a lot of mass from an asteroid between you and the Sun. In fact, water is very good for this, and as I’ve suggested elsewhere, building a habitat out of reinforced water ice is actually a better idea than trying to fabricate a large metallic structure.
The biggest problem in operating on the Lunar surface isn’t supplies or the energy required to deliver them; once you have materials to orbit it takes relatively little effort to get them to the Moon’s orbit or to Earth escape trajectory, as long as you aren’t in any particular hurry. The biggest hurdle is dealing with the Lunar dust. As the Apollo lunar missions demonstrated, the dust gets into everything, sticks to it due to electrostatic attraction, and gums things up to no end; see NASA/TM—2005-213610/REV1 The Effects of Lunar Dust on EVA Systems During the Apollo Missions, James Gaier, April 2007. While it seems like a minor issue at first, it turns out to be a major problem in using any mechanisms or moving machinery for any extended period of time, and may well be a health risk as well.
Not all asteroids are in the Asteroid Belt. In fact, there are a class of asteroids called Near Earth Objects, many of which take less energy to get to than the Moon. (The downside is that they have virtually no gravity, so you can’t rely upon their mass to swing around, but that isn’t a huge problem, especially if you are going to perform initial surveys with robotic probes, and allows you to potentially move them slowly to a more accessible orbit.) Mining asteroids for resources is way easier than hauling stuff up from the Lunar surface, even dismissing other considerations, and will be the likely route for sustainable and viable human presence in space.
That being said, the continued exploration of the Moon is a great boon scientifically to planetologists and other researchers, and allows us a better understanding of the composition other planetary bodies. Far from being “another one of those dumb things that NASA always knew was true but had to “prove” for publicity?” as ignorantly stated by another poster, it is exactly the type of research that NASA is chartered to do, and that it does so well, typically within budget and schedule. If the primary expectation of NASA were to perform these types of missions rather than fantastical human space missions of questionable scientific merit, the agency would not be as ridiculed and cash-strapped.
You are talking about taking TONS of mining equipment. **Are the astronauts going to be mining for a few days or MONTHS to get what they came to get **? Hopefully they are bring back hundreds if not thousands of tons of water/fuel they have mined back with them, which was the whole point of going in the first place. A lower delta V means hundreds if not thousands of tons of fuel that ARE SAVED because it is easier to get there and back.
There is plenty there in the margins/savings for some extra food and water and air while the astronauts twiddle their thumbs going there and back.
In addition, all that crap they are taking there and back can be used as shielding.
I’m just extending upon your statement about the accessibility of asteroids. I’m not particularly interested in debating for the sole purpose of argumentation. My objective is a rational and informed discussion of the benefits and problems with space exploration and exploitation.
In terms of resources, it is fairly cheap to return material to Earth, provided that you aren’t in any hurry to do so. Within the asteroid belt and closer, light pressure is adequate for solar sail propulsion, or you can use high impulse nuclear pulse propulsion (a la Project ORION) provided your object can withstand the acceleration forces without coming apart like an overbaked cookie. However, this tends to miss the point, to wit that the advantage of being able to exploit raw materials in space is to use them to construct or fabricate stuff in space rather than drag it up from Earth or some other planet. This is a sine qua non of any credible and sustainable human presence in space.
Certainly. My point is that the longer you journey the more shielding you are going to need. For a 3 day trip you can chance it…pretty much what the astronauts who DID make the trip there actually did. They gambled. However, a trip to the asteroid belt is going to take weeks or months…increasing the probability of something nasty happening en route…no?
As for a moon base, that could be sent to the moon unmanned and prefabricated. I suppose you could do the same with a possible asteroid habitat too…but you still have the trip to accomplish.
Tons of mining equipment can be sent to the moon just the same as to the asteroid belt. It can be sent unmanned, as can the habitats. However, when you actually get around to sending a manned expedition to put folks in those habitats then getting there quickly is more importantly than saving some fuel. And outfitting a manned expedition to an asteroid is going to mean a LOT more supplies to get there, work there and get back than sending them to the moon. It’s basic logistics and astrogation. Logistically, it’s also easier to support a moon base than to support a permanent facility on an asteroid…if that’s what we are talking about. If you want to mine for metals and such then it’s probably better to look at automated facilities.
But it’s going to cost more to send people out to such a place than it would to send them to the moon. Again, basic logistics. It’s also going to be MUCH more risky to send people out there than to the moon.
Perhaps, though most of the long expeditions NASA is looking at are multi-stage affairs, with unmanned flights followed by quick dashes with the manned parties to already pre-arranged facilities. No one, afaik, is talking about sending the entire expedition along with all their equipment and stores in one huge trip. THAT would REALLY cost a lot more.
Probably. At any rate, I think it’s an important discovery that there is ice on the moon, and that some country will take advantage of it at some point. I have my doubts it will be the US at this point, which is sad, but SOMEONE will. Hopefully some country will also go to Mars in my lifetime as well.
I don’t know if this is intentional or not, but you seem to be very dense. Let me spell it out for you:
[ul][li]There are asteroids that are as close or closer than the Moon, and require less impulse to reach[/li][li]There is no protection against radiation on the Moon’s surface; you would have to dig down into the regolith for protection, just as you would need to stay on the far side of an asteroid[/li][li]The Moon’s surface itself is a difficult environment for equipment to function due to the tribological challenges of Lunar dust as discovered during the Apollo landing missions[/li][li]In term of extracting and using resources for a self-supporting human presence and exploratory effort, it is easier to mine asteroids and comets than it is to pull mass up from the Moon’s surface[/ul][/li]
And I don’t know where you are getting your ideas about “most of the long expeditions NASA is looking at are multi-stage affairs, with unmanned flights followed by quick dashes with the manned parties to already pre-arranged facilities,” but thus far NASA has not done more than undetailed conceptual studies of manned interplanetary missions, and the proposals based upon the current Constellation system are all unitary missions with single modular vehicle systems that are integrated in Earth orbit (Earth orbit rendezvous), akin to the Apollo Command/Service Module arrangement, but slightly larger. As far as I can tell, you’re pulling this stuff straight out of your ass.
Ah, thanks for the condescending reply Stranger. You can always be counted on for such, ehe?
News to me. I assume you are talking about an asteroid who’s orbital mechanics bring it into such a range and on a long elliptical. Which would be fairly useless for when it goes back out (not to mention the fact that you’d need to wait until it DID get that close). If you have a cite for what you are talking about it would be better than what you actually gave. Thanks in advance for fighting my ignorance.
No shit…did I deny this? Perhaps you need to take some reading lessons…or perhaps read what I actually wrote. No where will it say that an astronaut is protected from radiation while on the moon.
Don’t asteroids have dust as well? And a microgravity environment (such as on an asteroid) would also provide a lot of engineering challenges. Life is full of tradeoffs.
But let’s make this easy, ehe? Do you have a cite that shows it would be easier (safer, less costly, etc) to create a permanent base on an asteroid as opposed to one on the moon? If so, then trot it out, instead of trotting out insults and misreading of my post. Frankly I don’t know why this silly thread has set you off, but you seriously need to chill out.
You have a cite for this assertion, right?
The manned mission (Constellation) is not for a permanent base…it’s a short duration flight and exploration mission. I know of no serious program that is currently being looked at that is NOT a multi-stage affair…including Bush’s (NASA) plans for a permanent base on the moon, which, IIRC, was to land a habitat on the moon first, and THEN send the astronauts. Perhaps the Chinese are thinking in terms of a one shot deal, but then, like Constellation, it’s a short duration foot prints and photos type mission.
All of the serious missions being considered for Mars are manned/unmanned affairs. If you have information to the contrary, again, feel free to provide it. If you are ASKING me for where I’m getting my info from, I’d be happy to provide, though I seriously didn’t think this was even in question, since no one has gotten passed the planning stage for ANY long duration type missions.
No, I’m talking about Near Earth Objects. Please make the minimal effort to copy those words into a search engine and educate yourself on the topic. You might also read the report I linked to which details the dust conditions on the surface of the Moon, and why they pose such a significant difficulty to long-term operations. Asteroids, lacking a significant gravity field, will not collect an inches-thick coat of ionized dust.
The expense of lifting materials off of the surface of the Moon or another planet in a significant gravity field versus extracting it from a small planetoid is obvious and does not require citation. There are no credible estimates for the cost of establishing a permanent, self-sustaining human presence in space because that is far away from existing experience. Any cite I would present that provided detailed figures would necessarily be fatuous at best.
Constellation is not a “manned mission” but a space transportation system development program consisting of several different classes of heavy lift booster, a space capsule module, a service module, and an orbital injection propulsion system, plus a lunar lander and other mission-specific equipment. Again, there are no detailed proposals by NASA for long-term habitation of the Moon or any other celestial body, so your talk of multi-stage missions, et cetera is another example of speaking without knowledge.
I know what a Near Earth Object is, thanks. Pretty much what I said…i.e. objects that have orbits that swing them into proximity of Earth and then back out again. AFAIK, there are no major asteroids who’s orbital mechanics makes them closer than the moon on a consistent basis. No?
(That’s what I was asking you to cite btw, since you seem to have missed it)
It requires a cite to back up your assertion that it’s cheaper, safer and easier. I’d think this would be a pretty easy cite for you to get, considering how dismissive you’ve been on the subject. Feel free to provide it any time.
FTR, I’m not disputing that it takes less thrust to lift off from an asteroid than from the moon…that’s your own strawman. I’m saying it would be more expensive to attempt a long duration mission to an asteroid than it would be too the moon. If I’m wrong then provide a cite and I’ll retract what I’ve said.
You are right…for some reason I was thinking that Constellation was the name of the program NASA was looking at for a manned mission back to the moon, but I didn’t bother to look it up and having done so I see that it’s a program for a new generation of manned launch vehicles that could be used for a variety of missions, including one to the moon.
Well, your cite is your post, I suppose. For my part, I freely admit my own perception of this comes from places like Discovery Channel, History Channel, TLC, and the NASA cable channel, where they discuss possible extended missions such as those to Mars. While I admit that these types of sources may not be the most solid, claiming I’m pulling this out of my ass is a bit fatuous on your own part.
Again, why you are so hostile here is beyond me. I can see why some political threads inspire hostility as you are showing here, but I’m mystified as to why THIS thread has inspired you to such levels. I don’t recall kicking your dog or pissing in your Wheaties, but obviously you are having some issues here.
Clearly, you do not know what a NEO is. Until such time as you educate yourself up to the level of knowledge that you are pretend to have on this topic, I’m not really interested in engaging in a discussion with you.
If you can’t provide a cite, it generally indicates that one doesn’t exist. That’s the whole point of asking. Until you provide one, it would make much more sense to just ignore you, since your point has not been established as having a factual basis.
Irony is not an element in the periodic table. xtisme has not provided a single citation save for vague references he saw at some point on junk food pop-sci t.v. programs. He clearly doesn’t understand that the Near Earth Objects include objects that are closer and have lower orbital energies than the Moon, and the argument he seeks to engage in is pursuant upon deliberate ignorance of this fact. I’d be pleased to have an intelligent, informed discussion with people on this topic, which is of interest to me. I am not interested in contributing to a rambling, tangential argument or having to forcibly educate the persistently obtuse on the basics of planetary science, space environments, and orbital mechanics.
At any rate, I think it’s an important discovery that there is ice on the moon, and that some country will take advantage of it at some point. I have my doubts it will be the US at this point, which is sad, but SOMEONE will. Hopefully some country will also go to Mars in my lifetime as well.