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(Space.com)   Hold everything. NASA is sending men back to the moon   (space.com) divider line 61
    More: Unlikely, NASA, SLS, John Logsdon, lunar exploration, lunar orbit, professor emeritus, space launch, Deep-Space Station Missions  
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4089 clicks; posted to Geek » on 09 Nov 2012 at 9:20 AM (1 year ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2012-11-09 12:49:22 PM

entropic_existence: cman: Khellendros: cman: Not really. We have a lot of technology that can get us there, it is simply a matter of logistics. It takes 6 months to get from the earth to mars and really, stocking enough food, water, oxygen, fuel, and various supplies for human survival is extremely difficult that far away from earth. Plus, there is also the matter of atrophy. In a 0 gravity environment, your muscles that keep you standing upright atrophy. 6 months of that is gonna be extremely harsh on the human body.

We still have a ways to go before we can send a man to mars.

You do know that people have been on the ISS much longer than 6 months, right? They have quite expanded routines for muscle conditioning and fighting atrophy. And stocking/supplying it is routine for long periods of time. There's entire logistical processes and procedures to manage supply, and they're quite mature. Sure, they'd need to be adapted and altered for a vehicle with different purposes, but it's not like it's far-fetched.

I am not saying that it is impossible. All I am saying is that we still have a way to go before we can send mankind to mars. I dont think we are quite ready with the realities of such and we should start getting ready. I would LOVE to see one of our own walk on Mars. I want to have it happen before my lifetime is over, and with the way things are progressing, I dont see that happening.

It isn't the duration that is the problem. ISS missions are already months long, and there has been at least one Astronaut who spent over a year in space for single-duration. The real problems for Mars missions right now is dealing with radiation. We aren't entirely sure what the total exposure levels would be and how much shielding is needed for the craft. And that isn't limited to the flight but to the time spent on Mars as well.


Two things are changing that... Well, possibly three.
The first is that curiosity took measurements on its way there, showing the radiation is not as bad as previously thought.
The second is that NASA is working on better electronic shielding.

Problem at the moment is that not much money is being put into deep space exploration and we don't have many missions slated for there.

The third thing: an unintended side effect of obama's commercial space program is that suppliers are now paid per flight, instead of just for making the rocket.
So they need more missions to make the pork flow, which will drive the development of more habitable spacecraft.
In order to get billions from NASA you need to create the need for your rockets, which appears to be happening now.

...maybe.
 
2012-11-09 01:33:11 PM

dittybopper: All those issues go away when you get there faster, and we can get there faster than six months. In fact, with a modest Project Orion vehicle, boosted to Earth orbit by the equivalent of 3 Saturn V-class rockets and assembled in orbit, you could do a round trip to Mars and back in about 125 days, or just about 4 months. We have experience with that length of time being weightless (and it would actually be half that: There would be time on Mars where they'd have some gravity).


I assume 125 days is the travel time, but that article does not describe the boost/zero-g travel profiles.

Using an Orion drive with 2000 impulses (a number mentioned in the link), they'd be under acceleration (aka gravity) for an interesting fraction of the travel time. 2000 impulses / 125 days is 16 boosts per day, if they are evenly spread out. It would make sense to do more of them at the start and end of the trip, so as to accelerate to a cruise speed faster, and I would find it interesting to see how they'd process more than 16 nukes in a day, and how long it would take the shock absorber to release each burst of force. So the zero-G portion may be interrupted by many acceleration events.
 
2012-11-09 02:09:17 PM

Cythraul:
I don't even think we should be trying to do manned missions to Mars with our current level of technology. I keep reading about how extremely dangerous it is. Yes, yes, I know, nothing is discovered without risk.


Our technology is more than up to the challenge of getting people to Mars, we can probably be pretty certain that we can get them home as well. The technology isn't the problem. Do you have any idea how much that'd cost though? That's the problem, cost.

You'd have to either find a shiat ton of extra money OR reduce military spending... neither of which are realistically going to happen so you're unlikely to encounter the 2 - 4 year and 'all change' problem NASA encounters in politicians... who control the money.

But no, the technology is not the problem.
 
2012-11-09 02:59:32 PM

WelldeadLink: dittybopper: All those issues go away when you get there faster, and we can get there faster than six months. In fact, with a modest Project Orion vehicle, boosted to Earth orbit by the equivalent of 3 Saturn V-class rockets and assembled in orbit, you could do a round trip to Mars and back in about 125 days, or just about 4 months. We have experience with that length of time being weightless (and it would actually be half that: There would be time on Mars where they'd have some gravity).

I assume 125 days is the travel time, but that article does not describe the boost/zero-g travel profiles.

Using an Orion drive with 2000 impulses (a number mentioned in the link), they'd be under acceleration (aka gravity) for an interesting fraction of the travel time. 2000 impulses / 125 days is 16 boosts per day, if they are evenly spread out. It would make sense to do more of them at the start and end of the trip, so as to accelerate to a cruise speed faster, and I would find it interesting to see how they'd process more than 16 nukes in a day, and how long it would take the shock absorber to release each burst of force. So the zero-G portion may be interrupted by many acceleration events.


That was all worked out in the late 1950's-early 1960's. They'd process the nukes by making them in a standard envelope, and the mechanism would be similar to a soft-drink vending machine. They could spit them out the back fairly quickly, and the shock absorbtion was all designed.
 
2012-11-09 03:45:11 PM
2 questions. Where do I sign up? How many of you do I need to kill?
 
2012-11-09 06:13:21 PM

dittybopper: President Merkin Muffley: dittybopper: President Merkin Muffley: Bone loss as well and unlike muscle atrophy there seems to be no way to counter it.

Then we'll just have to get there faster, won't we?

Oh, man that's brilliant! Somebody call NASA, they've got untapped genius right here!

We have the technology to get there faster. It's just expensive, and we're not allowed to do it because of an international treaty that is applicable to weapons testing, but was written in such a manner to outlaw *ALL* nuclear explosions in space.

If we were to get that out of the way by amending the 1963 test ban treaty, then it would be like that line in "Mad Max": Speed's just a question of money. How fast you wanna go?


And physics. Twice as fast means twice the fuel expended means twice the fuel carried means twice the intertia.

How fast do I wanna go? C

How fast do I wanna stop? HELP SOMEBODY STOP THIS THING.
 
2012-11-09 06:24:22 PM
It would be interesting to see if Obama did announce a plan for a manned Moon base.

I mean, a lot of the same people that called Newt retarded for such an idea are also the people that cannot find fault with Obama, so it'd be interesting.

I think it is a retarded idea for other reasons. Mainly, cost (unless they plan to increase NASA's budget by reduced defense spending, which is pretty unlikely) vs rate of return.
 
2012-11-09 06:52:42 PM

dittybopper: MrBallou: Staging, not taking everything with you, etc. I'll let somebody else do the math. My point is that it's not the same as LEO and there are reasons to be there.

That makes sense if you do something useful at L2. One could make a better argument for the Moon itself, because there is the possibility of mining it for construction materials and fuel, and the gravity well you have to climb out of is much more modest than that of the Earth. You can't mine local resources at L2, though.

Just pulling numbers out of my ass, I find it hard to believe that it would be cheaper to send 5 payloads of 100,000 lbs to L2 for subsequent assembly and launch to than it would be to send 5 payloads of 170,000 lbs to LEO* for the same. In the first case, you get a total vehicle/fuel weight of 500,000 lbs, and in the second, 850,000 lbs.

I suppose you could mine and refine on the moon, and shoot it up to L2 for assembly, but then you have a large infrastructure, and that's extra cost. You've got to maintain a presence both on the moon and at L2. If you were going to do something like that, might as well just assemble in lunar orbit: You don't have the problems of drag inherent with LEO on Earth.

You don't *NEED* to worry about staging so much from orbit to wherever. You send up the payloads one at a time, assemble them in orbit, then you have a single stage to boost you out of orbit. One large stage from LEO is more efficient than a bunch of smaller ones to boost you to L2 for assembly, and then a subsequent (smaller) booster to get you to your ultimate destination. You could boost the LEO-To-Asteroid-And-Back stage to orbit pressurized but unfueled, and send up subsequent "space tankers" (essentially boosters with a big tank on on top) designed to rendezvous with the empty LTAAB and fill it up. And you could send up the crew module separately also. Obviously, you're going to want to use non-cryogenic fuels.

*Numbers based upon throw weights of Apollo CSM/LM combo ...


I am not a rocket scientist, so I could be grossly misunderstanding this, but I believe you can get to L2 with very little fuel cost by using a Lissajous orbit. So putting the assembly/refuel point at L2 would give you all the benefits of L2 over LEO (no aerodrag and reboosting required, lower fuel evaporation, and apparently it's a much more favorable environment for the hardware itself) with very little fuel cost.

Finally, there's this from actual rocket scientists:
A typical Mars departure delta-V of 4.3 km/sec (from LEO) is obtained with a perigee burn of less than
1 km/sec. Because of this we not only cash in our savings but the vehicle doing this last bit of work can be very
small. Its dry mass can be much smaller than for a traditional system or conversely our existing vehicles can do
proportionately larger tasks. For example, a Centaur class vehicle can move a 7t spacecraft from LEO to L2, refill
there, execute an Oberth exit burn, and retain enough propellant to lose over 40 lbs per day during the 8½ month
transit and finally execute a 2.7 km/sec insertion burn at Mars. In other words, a depot-augmented, long-duration
Centaur can move to Mars orbit what we can barely move to geostationary orbit on the largest rocket in the US
inventory using our existing approaches.
 
2012-11-09 10:48:30 PM
skiingisfun.files.wordpress.com
 
2012-11-09 10:51:18 PM

dwyw: So putting the assembly/refuel point at L2 would give you all the benefits of L2 over LEO (no aerodrag and reboosting required, lower fuel evaporation, and apparently it's a much more favorable environment for the hardware itself) with very little fuel cost.


Unless you plan to spend more than a handful of months in LEO putting the thing together, aerodrag and reboosting aren't an issue. They are for things like the ISS because we wish them to remain in orbit, but for something that is only going to spend 2 to 4 months in orbit before being launched, that's not an issue.

Also, you use storable liquid propellants to minimize evaporation, which is something you need to do anyway because you'll need to start the damn thing to come back home. Also, you needn't send it to LEO fueled, or even fuel it until right before you are ready to go. Assemble it in orbit first, then fuel it, the send it on it's way.
 
2012-11-11 12:46:29 AM
Turn the moon into a prison.

That's the only use for it. Mining is stupid. Colonizing is stupid.

Just turn it into a maximum security prison for lifers. Throw every piece of shiat that we don't want on Earth up there, and leave them in some bunker with solar panels and the means to grow some food and recycle their water. Make occasional (every 8 years or so) drops to check in on them and give them fresh supplies.

No bars needed. No worries about escape. They won't be going anywhere.
 
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