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Return To The Moon, Everything Old is New again
remcook
post Aug 1 2005, 04:20 PM
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Splitting manned and heavy unmanned launchers is not a bad idea though...
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RNeuhaus
post Aug 2 2005, 05:03 PM
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The solid roket booster, liquid propulsion are of old technologies dated from the decade 60. However, they are still necessary to put any object into the LEO. After that , I see that the technology has not yet improved much in utilizing other kind of propulsion: Electric propulsion utilizing the source from Sail Solar or nuke power to navigate from LEO to Moon and others planets.

The other thing that I am asking, I knew that the US Air force has captured some lost OVNI in long time ago by Nevada or New Mexico long time ago (around '30 to '40 decade) and I see that the man was not able to learn from the other kind of propulsion from the OVNI.

Rodolfo
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RedSky
post Aug 2 2005, 05:21 PM
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QUOTE (RNeuhaus @ Aug 2 2005, 12:03 PM)
The other thing that I am asking, I knew that the US Air force has captured some lost OVNI in long time ago by Nevada or New Mexico long time ago (around '30 to '40 decade) and I see that the man was not able to learn from the other kind of propulsion from the OVNI.
Rodolfo
*


"OVNI"??? Does that translate into "UFO"? Are you referring to the 1947 Roswell, NM UFO crash story/mythology/whatever??? I think you're in the wrong forum.

Regarding other-than-chemical propulsion for out of LEO.... a nuclear power upper stage was in development in the 1960's (NERVA)... but cancelled. Lately, nuclear propulsion is (was?) being looked at again with Project Prometheus.

RedSky

(P.S. maybe the warp drive/anti-gravity drive/ quantum phase drive, etc. was too damaged in the crash to reverse-engineer) wink.gif
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djellison
post Aug 2 2005, 05:24 PM
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RS - I agree, the UFO Nevada stuff isnt right for here.

Doug
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RNeuhaus
post Aug 2 2005, 06:54 PM
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QUOTE (RedSky @ Aug 2 2005, 12:21 PM)
"OVNI"???  Does that translate into "UFO"?  Are you referring to the 1947 Roswell, NM UFO crash story/mythology/whatever???  I think you're in the wrong forum.
*

RedSky and Doug, Sorry for the wrong forum with the kind of propulsion of UFO to send a man faster to moon. I apologize it. sad.gif

Rodolfo
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paxdan
post Aug 2 2005, 07:06 PM
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What frustrates me most is that we have the technology, we've done it before yet it's gonna take longer this time around than the last. IMHO the crucial thing missing is the opposition.

At the moment I feel like NASA is standing in a tracksuit at the start of a race still waiting for the other guy to show up. No point exerting itself too hard until the competition arrives and there is something to prove.

I don't think we're gonna see a serious attempt on moon/mars 'till china decides to join the fun (or the private sector embarrasses the pants off everybody by making the whole spaceflight thing cheap and cheerful... go Rutan!). Anyway china now has more experience of spaceflight than the US did when JFK gave his 'before this decade is out' speech; +10% economic growth per annum, it wouldn't surprise me if they're there by 2020.

Anybody else think the current shuttle debacle (danger to crew aside) is a good thing? Boring a hole in LEO is just that. If were gonna send people into space they might as well go somewhere instead of paddling around in the shallows 200km up.
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dvandorn
post Aug 3 2005, 02:57 AM
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QUOTE (RNeuhaus @ Aug 2 2005, 12:03 PM)
The solid roket booster, liquid propulsion are of old technologies dated from the decade 60. However, they are still necessary to put any object into the LEO. After that , I see that the technology has not yet improved much in utilizing other kind of propulsion: Electric propulsion utilizing the source from Sail Solar or nuke power to navigate from LEO to Moon and others planets...
*

The problem with using low-thrust, long-burn propulsion systems to send people to the Moon is they don't get you going fast enough, quickly enough.

The van Allen belts are really dangerous -- if you stay there for very long. The Apollo astronauts who went to the Moon spent only a few hours passing through the radiation belts, and they were going at some of the highest speeds they would attain while they traversed the belts.

And they still got a measurable dose of radiation. Not even close to a critical dose, but measurable.

Now, an ion or electric propulsion system is a good idea -- it accelerates a spacecraft slowly, over time, but because the thrust continues for days and weeks, the accumulated acceleration is potentially enormous.

But any of those propulsion systems, if used to get you from LEO to the Moon, would continually create a larger and larger Earth orbit, taking weeks to accelerate to an orbit large enough to place the spacecraft into the Moon's gravisphere. And you would spend many, many days at a stretch passing through the van Allen belts. Over and over.

You would need some really *serious* radiation hardening to build that kind of vehicle. I don't think we know how to do that, yet. At least not well enough to commit a crew's lives to.

The same problem applies to using aerobraking to decelerate returning lunar spacecraft into Earth orbit, possibly to dock with the ISS. Aerobraking requires a lot of passes through the upper atmosphere, starting with a very large, very elliptical orbit and reducing a little speed on each pass to reduce the apogee a few hundred km on every pass, until you're in a position to establish a circular orbit at ISS altitudes.

And that orbit's apogee would slowly dip through the van Allen belts, over and over, and of course since the spacecraft slows down at apogee, it would spend very long hours on each aerobraking orbit traversing the hearts of the radiation belts.

For the foreseeable future, if we're going to fly men to the Moon and beyond, I think we need to use whatever it takes to build up a really fast exit from LEO, to minimize the time spent in the van Allen belts. Or else you risk damaging your spacecraft, not to mention your crew...

-the other Doug


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RNeuhaus
post Aug 3 2005, 04:39 PM
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QUOTE (dvandorn @ Aug 2 2005, 09:57 PM)
...
For the foreseeable future, if we're going to fly men to the Moon and beyond, I think we need to use whatever it takes to build up a really fast exit from LEO, to minimize the time spent in the van Allen belts.  Or else you risk damaging your spacecraft, not to mention your crew...

-the other Doug
*

I am very glad to hear of your very good explanation. I was not aware of many topics. The frigthening thing to pass the Van Alley Radiation Belt (http://en.wikipedia.org/wiki/Van_Allen_radiation_belt) where there is a high concentrations of sun radiations (X cosmic rays). Hence it is perfectely understandable that the manned space must travel thru it as short time as possible. About the slow accelaration of ion engine, I was afraid of that and I am accepting it. I think it should be a good candidate for long trips such as to Venus, Mars and beyond).

I like one of the proposal of Werner Von Braun, earth orbit rendezvous. It is safer for astrounauts who will reach to LEO (with up to 40 G??) by the SRB and docking with the 2nd stage LOX rocket sent by another SRB with external tank to impulse from LEO to moon.

Anyway I still wear diaper for space knowledge and this forum is great in sharing the knowledge, interests and ideas.

Rodolfo

P.D. Corrected the word: knowledgment to knowledge.
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deglr6328
post Aug 3 2005, 05:29 PM
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QUOTE (RNeuhaus @ Aug 3 2005, 04:39 PM)
Anyway I still wear diaper for space knowledgment and this forum is great in sharing the knowledgement, interests and ideas.

Rodolfo
*



blink.gif I....think something may have been lost in the translation on that one... tongue.gif wink.gif
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MiniTES
post Aug 4 2005, 02:01 PM
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Just how much acceleration in G's would you get out of an unmodified SRB, assuming maybe a 20 ton payload plus the liquid-fueled upper stage?
Personally I think it's a good idea to use them if you can solve that problem - sure, you can't shut them down, but in reality how often do you shut off an engine during manned spaceflight? And it will be "simple", "soon", and inexpensive to develop. I would assume you can cut patterns in the fuel to keep the acceleration to an acceptable level.


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RNeuhaus
post Aug 4 2005, 03:03 PM
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QUOTE (MiniTES @ Aug 4 2005, 09:01 AM)
I would assume you can cut patterns in the fuel to keep the acceleration to an acceptable level.
*

I imagine yes since the man cannot withstand an acceleration greater than 10 G for many seconds (I suppose it)

Rodolfo
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MiniTES
post Aug 4 2005, 03:17 PM
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QUOTE (RNeuhaus @ Aug 4 2005, 03:03 PM)
I imagine yes since the man cannot withstand an acceleration greater than 10 G for many seconds (I suppose it)

Rodolfo
*


So what would the actual acceleration be from an unmodified SRB with regularly cut fuel?
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MiniTES
post Aug 4 2005, 03:17 PM
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QUOTE (RNeuhaus @ Aug 4 2005, 03:03 PM)
I imagine yes since the man cannot withstand an acceleration greater than 10 G for many seconds (I suppose it)

Rodolfo
*


So what would the actual acceleration be from an unmodified SRB with regularly cut fuel?
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Ames
post Aug 4 2005, 03:25 PM
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QUOTE (MiniTES @ Aug 4 2005, 04:17 PM)
So what would the actual acceleration be from an unmodified SRB with regularly cut fuel?
*


Look at http://en.wikipedia.org/wiki/Space_Shuttle..._Rocket_Booster

Quotes 3,300,000 lbf (14.7 MN) at launch
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djellison
post Aug 4 2005, 03:38 PM
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14.7MN on an LV of 589 ton SRB + 80 ton 2nd stage+module = 21 m/s^2 or 2.2G

The real carefull issue is how to design the SRB to throttle down at the end of the burn - otherwise with 14.7 MN on a nearly empty SRB of 86.1 ton, you would have 9G smile.gif

Doug
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