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The Cold Equations Of Spaceflight
Space Daily.com ^ | 9/9/05 | Jeffrey F. Bell

Posted on 09/09/2005 5:26:35 AM PDT by nuke rocketeer

In the past month, we have been blessed with numerous leaks from NASA of various study documents relating to the new boosters that will be needed to carry out the new manned moon program. I've been monitoring the large volume of Web chatter about these plans, and have noticed a disturbing theme therein. Many Space Cadets are expressing dissatisfaction with these leaked NASA plans. They say that the Shuttle-derived boosters are too primitive, too expensive to develop, too expensive to operate, and not inspiring enough. They can't understand why we will be returning to the Moon with rockets and space capsules that look like minor variations of those used in the Apollo program 40 years ago.

(Excerpt) Read more at spacedaily.com ...


TOPICS: Business/Economy; Government; Miscellaneous; News/Current Events
KEYWORDS: exploration; nasa; rockets; shuttle; space
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The best explanation of why the DC-X, NASP, and VentureStar died and why we are going back to the future.
1 posted on 09/09/2005 5:26:35 AM PDT by nuke rocketeer
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To: nuke rocketeer

Has anyone figured out how they are going to get through the Van Allen Radiation belt alive?


2 posted on 09/09/2005 5:30:08 AM PDT by OldMagazine
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To: nuke rocketeer

Let private enterprise do it. They're already doing brilliantly in near space.


3 posted on 09/09/2005 5:31:50 AM PDT by RoadTest (For Heaven's Sake)
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To: nuke rocketeer

We can't even keep the insulating foam from coming off of the shuttle's external fuel tank. Space technology will advance ONLY when it become profitable and private industry starts paying more of the bills.


4 posted on 09/09/2005 5:33:14 AM PDT by manwiththehands
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To: nuke rocketeer

bttt


5 posted on 09/09/2005 5:33:40 AM PDT by Dark Skies ("The only way to find yourself is in the fires of sorrow." -- Oswald Chambers)
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To: nuke rocketeer

Can't find enough dilithium crystals?...........or melange......


6 posted on 09/09/2005 5:41:46 AM PDT by Red Badger (United States Marine Corps.....An army of WON!...........)
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To: nuke rocketeer

So the problem seems to be that of being able to carry enough fuel. Which has to be of the conventional kind.

I can't imagine nuclear power driving a space ship and especially a manned one. The mass of fat-nucleus atoms needed to shield it would render it literally impossible.


7 posted on 09/09/2005 5:45:26 AM PDT by The Red Zone (Florida, the sun-shame state, and Illinois the chicken injun.)
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To: nuke rocketeer

You mean I'm stuck here???


8 posted on 09/09/2005 5:46:15 AM PDT by HarleyD (I live in my own little world because I enjoy the company.)
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To: nuke rocketeer
The best explanation of why the DC-X, NASP, and VentureStar died and why we are going back to the future.

I fully agree, but try telling some other Freepers that Burt Rutan does not have the ability to reach orbit, and given his budget never will, and you will need asbestos underwear.

9 posted on 09/09/2005 5:50:55 AM PDT by Yo-Yo
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To: nuke rocketeer
The approach that seems to make the most sense to me is using a progressive rail gun built into an equatorial mountain slope, to shoot a vehicle into space. Thus allowing a theoretical 0% usage of on board fuel to attain orbit.
Entering the atmosphere already above 10,000 (half of the mass of the atmosphere) would decrease structural loading. A high energy laser could also super heat the flight path just before to lesson resistance (like lightning splitting the air). Additionally, a sabot shell could be used.
The progressive capability of a very long rail gun, could achieve required speeds without exceeding survivable G loads.
Reentry vehicles could then be made much more robust.
10 posted on 09/09/2005 5:53:00 AM PDT by SampleMan
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To: The Red Zone

An Orion could, but the Atmospheric test ban Treaty puts a legal bar to this vehicle, and the fact that it puts all kids of fallout in the atmosphere puts an ethical and environmental bar in front of it.


11 posted on 09/09/2005 5:58:14 AM PDT by nuke rocketeer
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To: OldMagazine

The Apollo astronauts got through it alive. The key for that is to go through it quickly.


12 posted on 09/09/2005 5:59:10 AM PDT by nuke rocketeer
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To: HarleyD
You mean I'm stuck here???

Predestination is an ugly thing, Harley.... ;-)

13 posted on 09/09/2005 6:00:55 AM PDT by r9etb
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To: nuke rocketeer
Like Gen Honore said, if it were easy, we would have already done it. We're not stuck on stupid.
14 posted on 09/09/2005 6:01:10 AM PDT by beef (Who Killed Kennewick Man?)
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To: RoadTest
Let private enterprise do it. They're already doing brilliantly in near space.

Is private enterprise somehow immune to the Cold Equations of Space? They're not.

And they're also not immune to the Cold Equations of Return on Investment. Aside from the fabulously profitable comsat market, private enterprise hasn't got much incentive to go into space right now.

15 posted on 09/09/2005 6:03:05 AM PDT by r9etb
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To: beef

Yep. Anything we do in space is going to be hard AND expensive. TANSTAAFL. I would like to see us substitute a modernized Dyna-Soar for the modernized Apollo in the new launch vehicle.


16 posted on 09/09/2005 6:05:20 AM PDT by nuke rocketeer
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To: nuke rocketeer
Ah... dreams dashed on the hard rocks of reality.

Oh well, back to Traveller.

17 posted on 09/09/2005 6:06:57 AM PDT by Junior (Just because the voices in your head tell you to do things doesn't mean you have to listen to them)
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To: nuke rocketeer

Basically an atom bomb with wings??


18 posted on 09/09/2005 6:08:53 AM PDT by The Red Zone (Florida, the sun-shame state, and Illinois the chicken injun.)
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To: r9etb

Would there be some way to get around this by keeping some of the propulsion system earthbound? Like a humongous slingshot or catapult?


19 posted on 09/09/2005 6:11:04 AM PDT by The Red Zone (Florida, the sun-shame state, and Illinois the chicken injun.)
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To: The Red Zone

Yes. See my post #10.


20 posted on 09/09/2005 6:19:21 AM PDT by SampleMan
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To: SampleMan
Entering the atmosphere already above 10,000 (half of the mass of the atmosphere) would decrease structural loading.

10K isn't THAT rarefied. Even if you mean miles.

21 posted on 09/09/2005 6:21:13 AM PDT by The Red Zone (Florida, the sun-shame state, and Illinois the chicken injun.)
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To: SampleMan

Rail gun, pshaw. I wanna see a giant coil spring compressed and go SPROI-OI-OI-OING up a tube.


22 posted on 09/09/2005 6:23:04 AM PDT by The Red Zone (Florida, the sun-shame state, and Illinois the chicken injun.)
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To: The Red Zone
I can't imagine nuclear power driving a space ship and especially a manned one. The mass of fat-nucleus atoms needed to shield it would render it literally impossible.

Distance is also a shield.

Once you get to Low Earth Orbit via conventional means, you can hook up to a nuke power section via tether (we can make long and very strong strings these days) and have it pull you to Mars orbit via high-efficiency ion drive

23 posted on 09/09/2005 6:26:29 AM PDT by SauronOfMordor
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To: The Red Zone
It is THAT rarefied. "THAT" being 1/2 the mass of the atmosphere. Of course it isn't space, you can breath fine, once accustomed at 10,000 feet. But the atmospheric loads on a vehicle below 10,000 are enormous. Thus why going Mach 1 on the deck takes so much energy.
A 20,000 ft mountain would of course be much better.
24 posted on 09/09/2005 6:27:00 AM PDT by SampleMan
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To: The Red Zone

It has been determined that the first man made object to truly leave the earth's bounds was a man hole cover from a nuclear test detonation tunnel. High speed imagery was used to calculate velocity.


25 posted on 09/09/2005 6:29:39 AM PDT by SampleMan
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To: The Red Zone
10K isn't THAT rarefied. Even if you mean miles.

Most of our satelites are well below 10,000 miles up. Care to reconsider?

26 posted on 09/09/2005 6:31:48 AM PDT by SampleMan
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To: SauronOfMordor

The world's longest extension cord, huh. Someone oughtta do the math for how heavy it would need to be in order to carry the requisite current... shoot, even to support itself against high atmospheric winds.


27 posted on 09/09/2005 6:32:01 AM PDT by The Red Zone (Florida, the sun-shame state, and Illinois the chicken injun.)
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To: The Red Zone

Nope, A HUGE thick hemisphere of steel with a crew compartment on top and injection ports to squirt a hydrogen bomb under it to detonate a few microseconds later. See this site
http://www.islandone.org/Propulsion/ProjectOrion.html


28 posted on 09/09/2005 6:32:25 AM PDT by nuke rocketeer
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To: The Red Zone
I can't imagine nuclear power driving a space ship and especially a manned one. The mass of fat-nucleus atoms needed to shield it would render it literally impossible

Not if you use the best fat-nucleus element available - the nuclear fuel itself. Design a ship whose uranium or plutonium can double as shielding. There will need to be some additional shielding against radiation from the fuel itself, but that's minimal.

29 posted on 09/09/2005 6:32:35 AM PDT by BlazingArizona
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To: SampleMan

Why don't I have to duck those pesky things while on the Albuquerque Tramway?


30 posted on 09/09/2005 6:33:09 AM PDT by The Red Zone (Florida, the sun-shame state, and Illinois the chicken injun.)
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To: BlazingArizona

If you brought together a layer of fissionable uranium heavy enough to stop the radiation of some presumably localized reaction, the shield would itself be well over criticality and so couldn't even be built. Plutonium? Same thing, except it's also a devil of a material to deal with structurally (goes through something like five phases in the solid state depending on temperature).


31 posted on 09/09/2005 6:39:52 AM PDT by The Red Zone (Florida, the sun-shame state, and Illinois the chicken injun.)
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To: The Red Zone
I had no idea Albuquerque was at 52,800,000 ft., or are you just tall? You did say miles.

Many low earth orbit sats are in fact at only a few hundred miles up.

My original point is that the exit velocity for a rail gun will be so high that atmospheric loading requirements will increase strength requirements. Starting the ascent at or above 10,000 ft, reduces that by half. There is also the engineering problem of burying that much structure. Much easier to build it above ground. Of course the vehicle would need to be in a contained tube, which is itself kept at less than normal atmospheric pressure. The less the better.
32 posted on 09/09/2005 6:40:24 AM PDT by SampleMan
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To: SampleMan

Tunnels have been dynamited and bored for roadways much further than 2 miles.


33 posted on 09/09/2005 6:47:00 AM PDT by The Red Zone (Florida, the sun-shame state, and Illinois the chicken injun.)
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To: The Red Zone

We're still stuck using Chemistry.

Hyrdogen and Oxygen burn fast. Controlled-explosion gets you off the ground. Gliding, friction and parachutes get you back.

A little improvement in technology gets you a little better rocket ship. But you're still stuck using the Chemistry of Hydrogen and Oxygen (and the various solid fuel-based ways of storing the two elements to get a controlled explosion later.)

Nuclear doesn't sound like the next wave except for deep space exploration satellites. Plasma engines give you a good boost in deep space over a long period of time but it doesn't get you off the ground or the moon or Mars.

Until we get a new form of Energy (not based on Chemistry or dangerous Nuclear), we're stuck doing what we're doing now. Slightly better crafts as slight technology improvements come on stream.

New physics, anti-gravity, something else is needed to make the next step.


34 posted on 09/09/2005 6:49:46 AM PDT by JustDoItAlways
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To: The Red Zone

I read an article in Discover a few months ago about space elevator plans. Very compelling if we can overcome materials restrictions. Once we get out of the Earth's Gravity well moving around gets a lot cheaper.


35 posted on 09/09/2005 6:52:49 AM PDT by smaug6 (We can't afford to be innocent!! Stand up and face the enemy.)
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To: The Red Zone
If you do the math, a rail gun would have to be well over 10 miles long to accelerate a vehicle to the required speed without exceeding 7 G's. The angle is going to have to be high if you are going to go "up", and it can't have much bend or lateral acceleration in the last few miles to prevent the same. This would lead to a very deep below ground requirement. Depth not distance being the problem for digging such a tunnel. We're talking much deeper than South African diamond mines.

Why would you want to do that, so that you could start from sea level?
36 posted on 09/09/2005 6:53:42 AM PDT by SampleMan
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To: smaug6

The climb-up-a-ribbon stuff?


37 posted on 09/09/2005 6:54:47 AM PDT by The Red Zone (Florida, the sun-shame state, and Illinois the chicken injun.)
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To: SampleMan

Chewing down the middle of an equatorial mountain would require the same thing.


38 posted on 09/09/2005 6:56:07 AM PDT by The Red Zone (Florida, the sun-shame state, and Illinois the chicken injun.)
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To: The Red Zone

No. It would require digging and building up to create the required exit angle. An angle that could be much less at 20,000 ft than at sea level. But not anything close to trying to dig that deep. The pressure and heat would not be anything like 5 miles deep. You sure are argumentative about a simple concept.


39 posted on 09/09/2005 7:01:25 AM PDT by SampleMan
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To: The Red Zone
Would there be some way to get around this by keeping some of the propulsion system earthbound? Like a humongous slingshot or catapult?

The biggest hurdles for that approach have to do with the fact that any ground-based boost method will induce high accelerations; and after that, the payload ends up having to go very fast in thick atmosphere.

The only way to handle the first problem is by adding length to your booster system. You'd have to handle the second by adding sheilding (heavy!), or somehow keep the atmosphere in the launch system at low density.

There is potentially a lot of merit in developing an air launch capability, although that's got to deal with other issues.

40 posted on 09/09/2005 7:04:40 AM PDT by r9etb
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To: The Red Zone

Yes.


41 posted on 09/09/2005 7:09:34 AM PDT by smaug6 (We can't afford to be innocent!! Stand up and face the enemy.)
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To: r9etb
You'd have to handle the second by adding sheilding (heavy!), or somehow keep the atmosphere in the launch system at low density.

An ablative shield possibly? Cast a shield from a material that carries away heat when vaporized? (Ice?)

42 posted on 09/09/2005 7:12:21 AM PDT by The Red Zone (Florida, the sun-shame state, and Illinois the chicken injun.)
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To: r9etb

Again, see my post #10. A rail gun, with a mountain top terminus solves both problems. Shooting a vehicle into space while keeping acceleration structural loads below 7 G. Atmospherics are greatly helped by not entering the atmosphere until the vehicle is already above the thickest part of the atmosphere (higher is better). And high energy beams may be able to split the flight path, thus decreasing resistance even more.


43 posted on 09/09/2005 7:13:28 AM PDT by SampleMan
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Comment #44 Removed by Moderator

To: bobbdobbs
You'll always need a rocket motor to burn at apogee in order to raise perigee. Perigee will always be at the last application of thrust -- or mountain height. You don't want your orbital perigee to be mountain height!!! Actually, it could be. A good heat shield on the nose would do the trick. Use the same shield for reentry. You are no longer talking about having to push a very fragile craft through, so beefy structure could withstand the loads. A much heavier structure could be used. Just the same, your compromise plan would likely be the most plausible. The fuel requirements would be tremendously reduced.
45 posted on 09/09/2005 7:54:36 AM PDT by SampleMan
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Comment #46 Removed by Moderator

Comment #47 Removed by Moderator

To: Spann_Tillman
organic nuclear fusion?

Does this involve large amounts of cabbage , beans and beer?........

48 posted on 09/09/2005 8:02:26 AM PDT by Red Badger (United States Marine Corps.....An army of WON!...........)
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Comment #49 Removed by Moderator

To: SampleMan
In theory a rail gun would probably be swell, but there are still significant issues to deal with.

First off is the fact that even at 29,000 feet (the top of Mt. Everest) you've got a hell of a lot of atmosphere to deal with, and you're going to hit it at well over 8 km/sec (you have to account for drag losses in your exit velocity). You can't be going straight up -- your velocity has got to take you in a ballistic trajectory that forces you to remain in the sensible atmosphere (which lasts up to ~400,000 feet) for quite a long time -- several minutes, at least. Note that the Shuttle sheds most of its orbital energy, and thus gains most of its atmospheric heating, above 200,000 feet. Bottom line is that there are tremendous heating issues to deal with, even with a rail gun.

In essence you're reversing the ballistic missile re-entry problem. (Harvey Allen's famous work on re-entry body shapes is summarized here, with a good assessment of the heating issues involved.)

An alternative is to use a railgun to boost the vehicle to a "respectable" speed to get it up high, and then use rockets to finish the job. The problem there is that the power overhead for the railgun probably increases tremendously due to the vastly increased launch mass.

You've also got to deal with the problem of how to move your great big mass through the long tunnel. You've got probably surmountable alignment and smoothness issues, but you've also got to deal with holding the payload in the center of the gun. Do you put it on rollers?

Finally, you've got to figure out a way to pull the air out of your tunnel, but still allow the payload to get out safely. This means a door of some sort that has to be big and heavy enough to keep air out, but must be nimble enough to open quickly, when the payload is close to the exit. Unfortunately, the act of opening the door will let the air come cascading in, which will lead to severe turbulence, buffeting, and shock waves as it rushes down the tunnel and comes into contact with the hypervelocity payload. Your tolerances are shot at that point, and you'd be in significant danger of hitting the wall, which would be a disaster.

So there's a huge design issue there that can probably only be addressed by adding "non-propulsive" length and width to your tunnel, and/or by making a faster door. Note that if it takes one second to open the door, then you've got to ensure that your payload is at least 8 km away when you start to open it. If you've got any experience with supersonic wind tunnels, you'll recognize the likelihood that there will be a large shockwave coming down the tunnel toward your payload.

50 posted on 09/09/2005 8:11:48 AM PDT by r9etb
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