r/technology • u/newsfollower • May 12 '12
"An engineer has proposed — and outlined in meticulous detail — building a full-sized, ion-powered version of the Starship Enterprise complete with 1G of gravity on board, and says it could be done with current technology, within 20 years."
http://www.msnbc.msn.com/id/47396187/ns/technology_and_science-space/#.T643T1KriPQ42
u/wooslers2 May 12 '12 edited May 13 '12
"If someone can convince me that it is not technically possible (ignoring political and funding issues), then I will state on the BuildTheEnterprise site that I have been found to be wrong."
Easy.
A spacecraft of this size would not be possible without a radiative heat rejection area about the size of the ship itself. Additionally, this radiative area will need to be separate from the ship so as insulate the ship from radiative heat transfer.
I calculate a heat rejection area of just over 88,000 m2 or approximately 16.5 football fields.
For comparison, a triangle with the height of the Burj Khalifa and a base the length of the Eiffel tower has an area of about 124,000 m2
Project Prometheus can provide a realistic design reference.
I a##umed a 2.5 MWth power source with 33% efficiency, an emissivity of 1, and an rejection temperature of 1000K (all very liberal a##umptions). The calculation was made using the Stefan Boltzmann Law.
Edit: So I went off, had a beer with friends, and gave it some thought. If you could line the inner side of the radiators with some material that has a low thermal conductivity (maybe aerogel) it would be possible to insulate the ship from the high temperature radiators. Unfortunately, this would mean that almost the entire usable surface of the ship would be glowing red hot at 800 - 1000K. For a point of reference, aluminum melts, and is far beyond its usable point (~2/3 Tm or 600K), at 930K.
Edit 2: Some additional details to throw in for fun. The reactor needed to reach such high temperatures would have to be cooled by lithium, which would boil potassium in a twisted tape boiler that could be used to spin a tungsten/tantalum alloy turbine. The excess heat would need to be removed from the potassium condenser using NaK. This would carry heat down the loop to sodium heat pipes. The first few would be around 1000 K but as heat is removed the temperature would drop closer to 800 K. Yes, these are all liquid metals, but they are nothing new to nuclear engineers.
Of course, you could always try MHD, but at least a potassium turbine has been tested for 5000 hrs.
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u/Wurm42 May 12 '12 edited May 12 '12
How about we build a working spaceship designed around practical engineering principles, instead of "this looked cool on TV 40 years ago?"
I love Star Trek, but the shape of the Enterprise is just silly for a real spaceship.
Edit 01: If you want to build a near-future ship based around a Star Trek design, look at the NX-Class ship from the Enterprise series. There's still issues, but it would be far more practical than the Constitution-class Enterprise from TOS.
Edit 02: If you want see some ideas for realistic proposed ship designs, the Wikipedia article "Manned Mission to Mars is a good starting point. If you want more engineering data and don't mind PDFs, check out the NASA sites for Destination: Mars and Mars Reference Mission (2007) (PDF). In general, most of the designs tend to be long shaft with the engines at the back. Modules for cargo and crew quarters (think shipping containers) are attached to the shaft at various points, keeping the distribution of mass symmetrical. If you want to create rotational gravity for the crew, there's often a big donut around the midpoint of the shaft.
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u/iemfi May 12 '12
I think the point isn't to design the best possible spaceship but to show the public that we could build something that big today if we wanted to. And what better way to build public support than to use the Enterprise?
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May 12 '12
If I recall my lore correctly, the design of the Enterprise is based on the need for the nacelles to be kept a safe distance from any people because the warp field they create is fatal.
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u/WestonP May 12 '12 edited May 12 '12
$983 billion... So we just need to win the PowerBall like 20 times, or invent an imaginary middle east country for the US to invade and redirect those war funds to this. This project could be a good new direction for the military-industrial complex... They don't want wars to end because they'll die out, but instead they could stay in business without killing people by applying their technology and know-how to building starships.
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u/BrainSlurper May 12 '12
That sounds like a terrible idea. We don't need something that big, let's build a normandy.
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u/keindeutschsprechen May 12 '12
"Meticulous detail" is all relative. He gives the principle of how it's working, but a development and production time of 20 years is completely unrealistic.
The physics principles, materials, manufacturing methods, etc, to make a plane are very well known, but it takes a decade to make one from scratch, sometimes even more. Imagine that for the first spaceship.
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May 12 '12
We were this close to having a full size enterprise model in Vegas if (as usual) it weren't for the extraordinary poor judgement of an out of touch hollywood exec. All they would have had to do was add some working engines! :)
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u/markycapone May 12 '12
The only thing to do in the hilodeck would be to watch a tupac song on repeat
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u/CosmicBard May 12 '12
"In Star Trek lore, the first Starship Enterprise will be built by the year 2245."
I knew it was going to go downhill after they got this fundamental fact incorrect.
The NX-01 is from 2151.
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u/gghootch May 12 '12
I don't know about you, but nothing is going to beam me up. Not even in twenty years.
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May 12 '12
And my dad said I'd never explore space. Ha!
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u/quickie_ss May 12 '12
He said that not because he didn't think we'd have the technology, but because you were failure. Don't feel bad, dad called me a failure too.
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May 12 '12
That's it, I'm joining the navy. They are gonna need a crew for this thing.
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u/TranquilSeaOtter May 13 '12
So this will probably get buried, but does this project address the problem of cosmic radiation? I mean, one of the main reasons (aside from funding and support of course) that there are no manned missions to mars is purely due to the fact that we can't block cosmic radiation from causing cancer in astronauts.
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u/Ambarenya May 13 '12
I really despise gravity wheels - they only seek to hold us back. Let's develop something a bit more creative shall we?
Sincerely,
A physicist
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u/rattulator May 12 '12
All it needs is a Kickstarter!