Spaceship Design

[GAHD]

How does one sell space{?}

 

How did they sell "the new world" soo many years ago?

[CraigD]

How did they sell "the new world" soo many years ago?

By virtue that it was rich with gold, in the early (16th Century) days of its selling. Other selling points quickly followed.

 

It so happens that, with the right technology, there’s a lot of easily gold in them ‘thar asteroids, and, better still, a lot of platinum, which has even more intrinsic (engineering, rather than ornament) value.

 

This could well be a breakthrough selling point. :)

[TheFaithfulStone]

How did they sell "the new world" soo many years ago?

 

They didn't have a stupid UN treaty about it "belonging to all mankind."

 

There's are literally TRILLIONS of dollars worth of metals on ONE asteroid, and trillions of dollars worth of H3 on the moon. But no-one can get ANY of it, because countries like Botswana didn't want to get shut out back when the US was the only country capable of going there and getting it.

 

Selling space isn't hard, it's leaving behind the people without vision or imagination that's hard. They tend to be sitting on most of the money.

 

TFS

[Roadam]

Politics .....................................

 

I think that most important ting mankind has to do in next decades is to put safe nuclear reactor rocket in space to use it as space taxi. And build something like X33 wit those new materials (nanotubes, liquid metals....) to put cargo in the orbit more cheaply.

[Qfwfq]

And there's also the unstated fact that exhaust velocity is a direct function of engine temperature. EV of 0.01c would require temps in the millions if not billions of Kelvins. Ouch!

Ion engines get around this to some extent by making the total thrust so small that excess heat can be handled.

But, :) uhm, particle accelerators give them kinetic energies much greater than rest energy without this meaning excess heat to dissipate... to the contrary, Rubbia's idea of adiabatic cooling slightly improves the useful forward velocity. Should NASA perhaps be taking lessons from places like SLAC, CERN, Fermilab, DESY or Frascati?

[Kayra]

But, ;) uhm, particle accelerators give them kinetic energies much greater than rest energy without this meaning excess heat to dissipate... to the contrary, Rubbia's idea of adiabatic cooling slightly improves the useful forward velocity. Should NASA perhaps be taking lessons from places like SLAC, CERN, Fermilab, DESY or Frascati?

 

Indeed they might have to if they want to exceed certain levels of thrust. The efficiency of such systems is pretty low, but consider this. What if we have a nearly unlimited supply of usable (VERY important term there) power, and only limited reaction mass. An accelerator might be the solution of choice.

 

Now all we need is a means of generating tremendous amounts of electricity, without generating huge quantities of heat. Combine that with a means of generating magnetic fields without the need for massive magnets, and you probably have the space drive of the future.

[Roadam]

Well, heat can be used to ionize gas or metal which the ion drive then accelerates. And sice heavier the atom is more energy is needed and less space is used to storage propelant.

[CraigD]

… Now all we need is a means of generating tremendous amounts of electricity, without generating huge quantities of heat.

Or all we need is a means of exhausting huge amounts of heat generated while generating tremendous amounts of electricity.

 

Even in current comparatively low-power spaceflight systems, waste heat disposal is a serious problem. With only refrigerators and radiators, it puts a stifling limit on the maximum power-to-size ratios of spacecraft.

 

In his hard-SF novel Sundiver, David Brin described a promising system to overcome this limit: a LASER pumped by heat to emit light (in the novel, the light is in the x-ray spectrum).

 

The idea is that a properly selected material could be made that, when heated to a certain temperature – or pumped by infrared radiation, in other words - emits photons not in the usual, wide-spectrum of glowing, but at a single wavelength defined by the resonant cavity of a LASER. Such a system could be many times higher power than a conventional radiator.

 

This fictional “LASER cooling” technology should not be confused with real, present-day technology that uses LASERs to cool such things as clouds of atoms and sub-atomic particles – their operating principle would be nearly completely different. It may be related to, and emerge from, current “thermoacoustic LASER” technology.

 

A giant, antimatter-powered, particle accelerator rocket is a far different idea than an antimatter "steam" rocket. The driving idea behind this later kind of rocket is simplicity – it is essentially just a very high temperature tea-kettle. Because it’s unlikely such a system could release exhaust gasses at a high fraction of the speed of light, it would be much more severely limited by its “mass ration” - the ratio of reaction mass to payload, though by my (and Robert Forward’s) calculations, it would be adequate for single-stage-to-orbit and interplanetary spacecraft.

 

If greater quantities of antimatter are somehow available, an “antimatter photonic rocket” could be feasible – allowing a rocket capable of a [math]\Delta[/math]v of .25 c with a ratio as low as 25% fuel:75% payload. The engineering challenges of such a rocket capable of high acceleration, however, may be more daunting than those of higher mass-ratio antimatter “steam” rocket.

[Moontanman]

Has anyone thought about the nuclear salt water rocket as a possible means to propel a space craft?

[Pyrotex]

Has anyone thought about the nuclear salt water rocket as a possible means to propel a space craft?

Yes.

Don't do it.

 

Super-heated salts from sea water will dissociate and do major damage to your "rocket" engine. Bad joo-joo, man.

[Moontanman]

Yes.

Don't do it.

 

Super-heated salts from sea water will dissociate and do major damage to your "rocket" engine. Bad joo-joo, man.

 

I would have thought that any engine that could take a continuous nuclear explosion would laugh off salts?

[Pyrotex]

...I wrote an unpublished SF story years ago, based on the discovery that a herd of "wahoots" was feeding near our Sun, inside the orbit of Mercury. They seemed to be made entirely out of plasma, held together by magnetic fields...

 

Wahoots – The Discovery

 

George’s footsteps echoed down the hallway as he took an absent-minded bite of his chicken salad sandwich and stared at the print in his other hand. He used his shoulder to punch open the door to the image analysis department of the University of Utrecht Solar Studies Building, and hurried over to the desk of his teammate.

“Hey, Zam. What’re these?”

The color print fell next to Zamir’s keyboard. George’s finger tapped the edge. It was just another of the tens of thousands of sun shots taken every day from SOHO-4a, one of two identical space telescopes positioned near the gravitational equilibrium point between the Earth and Sun. It took Zamir a few seconds to realize that it wasn’t just like all the others. There was a tiny blur -- actually a cluster of minute dots near the edge of the print. The scale at the top indicated they were about four solar radii from the Sun.

“You mean these things? Dunno what they are. Prolly just a patch of cosmic rays.”

He touched his keyboard.

“Okay… here’s a more recent… hello, they’re still there.”

With a few clicks of the keyboard, Zamir displayed a sequence of images taken about ten seconds apart.

“Wow, mon. They appeared out of nowhere, about twenty minutes ago.”

“Do they show up in shots from 4b? If they don’t, maybe we got a problem with 4a.”

“Sure. Lessee… Holy ****, mon! There they are again! They gotta be real!”

“Well, don’t just sit there drooling, see if you can triangulate their position.”

“Gimme a sec, I’m switching spectra first… Nope, they only show up in near infrared. Okay, let’s zoom in and triangulate...”

A detailed magnification appeared on his screen. A dozen circular blobs, each about the size of a thumbnail, appeared in shades of red and orange against a mottled black background. Bright green numbers flickered along one edge of the screen.

“Lessee, their range is 0.92 AU, just a smidge nearer than the Sun. They’re each about thirty kilometers wide and about two hundred kilometers apart. Their orbital velocity is… stationary? Holy ****, mon! Can’t be! I’ll notify Harvard and Berlin. They’ll know what they are.”

“Mmmph,” said George from around a bite of sandwich. “So, look right here at this one. Is that some kind of symmetrical internal structure? Zoom in all you can.”

Zamir and George bent forward toward the screen. Shades of green and orange cast shadows on their faces.

“I’ll be goddamned. Is this a joke? It’s gotta be a joke, right?”

Half of George’s sandwich plopped softly on the floor. Neither man noticed.

[CraigD]

Moderation note:

I moved a series of new posts from this thread to a new one, 15332, because they don’t have much to do with the thread’s original topic of the popularity of spaceship design ideas, circa 4/26/2006.

 

If there are no objections, I’ll close this thread, as 2 years is really way too long to leave a poll open. If anybody would like some other subthreads of this one moved to new threads of their own, just ask.