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You Can't Take the Sky From Me by SMPritchard You Can't Take the Sky From Me by SMPritchard
"Take my love, take my land, take me where I cannot stand. I don't care, I'm still free. You can't take the sky from me."

I got inspired by the themesong from Firefly (pretty much the greatest TV show in the history of TV, for those who don't know).

the background image of Earth is obviously not mine. But I'm fairly sure it's in the public domain, since it's from NASA. :P

The ship takes design elements from the NERVA rocket system that was investigated by NASA and the Atomic Energy Commission in 1952. NERVA (Nuclear Engine for Rocket Vehicle Application) is a Nuclear Thermal Rocket. It uses a nuclear reactor to heat liquid Hydrogen, causing it to expand and be forced out of the rocket nozzle, providing thrust. This particular assembly would be used to ferry cargo from Earth Orbit to the Moon, but other configurations could be used for missions to Mars. Unfortunately, NERVA was scrapped in 1972. In its (and other spacecraft's) place, after the close of Apollo, we got the Space Shuttles. Nothing against the Shuttles, but had we built a few of these, we might have already had a few Lunar and Martian bases by now. :/
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:iconwilliam-black:
William-Black Featured By Owner Aug 20, 2013  Professional Digital Artist
Beautiful NERVA reusable nuclear shuttle image. The line from the firefly theme as title is particularly appropriate.

Frankly I am of the opinion that we could have built and operated the RNS system – and that it would have been to our benefit to do so.

Having watched the Apollo moon landings as a child, and having grown up watching each succeeding unmanned exploration probe mission (with a few notable exceptions) succeed wildly, and, as an adult, having studied the numerous proposals to extend the range human space exploration – all of which have been set aside – I am aware of the undeniable fact that despite the magnificent achievement that was Apollo – it was selected over more ambitious proposals. Apollo being the minimum effort to successfully carry out manned lunar landings. This is not to impugn the spectacular success of the program – it is to place it in the context of government endeavor – which, sadly, is grounded in a narrow, range of the moment, interest.

Those NERVA’s sitting in their test-stands out at Jackass flats are a monument to this fact, as is Orion, as is the never built (all chemical) Nexus heavy booster.

Imagine for a moment how a heavy booster like the all chemical Nexus would have mitigated the expense of constructing the ISS.

Wernher von Braun, Ted Taylor, Freeman Dyson, along with a legion of other men, expended significant effort in endeavors, the staggering potential of which, in the end, fell on the deaf ears of government bureaucracy.

Having read the commentary below, I would observe the following: Every human action carries with it some form of risk – however, that fact alone does not provide a good reason “not” to engage in any particular endeavor. Risk can be mitigated; the requirement is merely that it be acknowledged.

Alarmists (the professionally “concerned” and the professionally “outraged”) have adopted the irrationality of zero-tolerance-to-risk as their standard of measure – and predatory lawyers (hungry to feed at the trough of donations and the monies of government coffers) empower a broad wave of activist causes which are aimed to increase government authority to limit achievement (often despite any real benefit to be derived from it) which is the motivation of the men driving these causes (their goal being power for the sake of power) and the pay-off for the legions of uninformed “activists” is the faux superiority of “saving the planet.” The obvious fact obfuscated (with intention) is that the edifice of our magnificent technological civilization has elevated the bulk of mankind out of the centuries of preindustrial poverty and suffering, and eliminated (largely) the millions who perished from plague and starvation through the broad sweep of history, for the largest part of which most of humanity spent their lives mired in a dreary, mind-numbing, grubbing for a mere sustenance level existence.

Arthur C. Clark is oft noted for the following quote: “I believe the day will come when very few members of the human race will even be able to point at the part of the sky where the earth is," however few people realize he was speaking in regards to the potential of Orion nuclear pulse propulsion to open the solar system to mankind.

Freeman Dyson’s words on the subject are also relevant and poignant: "I am still very strongly interested in spreading life beyond the Earth. Humans of course should go along. The most important thing, to me, is just enlarging the domain of life. Life has this marvelous adaptability – it's able to adapt itself to almost anything. Life has hardly even begun yet adapting itself to the universe – this little planet doesn't give it so much scope."

Lastly, I do not believe national governments will conquer the solar system – groups of individual men will.

I think it likely that these will be men who break the rules of the political game in order to do so, with the rational purpose of bringing about prosperity (for themselves and for their children’s children).

Groups of individuals will conquer the solar system. Nation’s as such will not initiate such things – perhaps, once the water is tested, nations might attempt to leverage some benefit, riding on the backs of the men who went there first.
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:iconpaladin208:
paladin208 Featured By Owner Feb 18, 2013
i LOVE that show.i AM a browncoat!!!
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:iconghostbirdofprey:
GhostBirdofPrey Featured By Owner Feb 12, 2013
I imagine a craft like this would have a hard time getting built due to the bad rap nuclear power gets. I remember hearing that people had a problem with the radioisotope thermal generator on New Horizons because they thought it was a bad idea to put something radioactive in space.
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:iconbobafetthotmail:
bobafetthotmail Featured By Owner Apr 15, 2013
While I'm for space stuff, I beg to say that it is a bit different.

An RTG is a very dumb thing you can toss around without a lot of fuss (actually quite a few old soviet ones sit in the open gathering rust and losing radioactive stuff in old military dump fields), as it is just a lump of radioactive alloy (usually with plutonium) that heats up itself by radioactive decay. Does not generate dangerous neutron radiation (well, you can stop what it does with a few cm of its own metal casing) and I think some actually did reenter atmosphere from old soviet stuff and none had really issues.

A NERVA is a smallish nuclear reactor cooled by liquid hydrogen, it isn't just generating a bit of heat with radioactive decay like a RTG. It generates a ridicolous amount of neutron radiation. The shield for it is just between the reactor and the rest of the craft, not all around it like a ground-based power plant (for mass reasons, a bigger shield would make it immobile).
In case of a reactor meltdown, that can happen anytime the hydrogen stops flowing while it is in the "warmed up" stage (equipment malfunction, space debris impact, human error), you have a chance of saving it by using the scram fuel (hydrogen stored in the spheres close to the engine) while inserting the moderator bars to stop the fission, but if that fails you have to jettison the thing or it can damage your craft (not a Hollywood style boom, more like silent radiation kill while it starts glowing yellow-hot).
Then it's a Chernobyl in orbit, as it is a naked melting reactor, not like a ground-based reactor that has tons of water coolant inside half a meter of steel pressure vessel plus meters of concrete shielding around it. Ground-based reactors usually take multiple days to meltdown even with a full cooling failure, this will meltdown in hours if not minutes. And god help anyone it falls on (if it does reenter, not a given of course, but certainly possible, depending on when the disaster happens)
So yeah, ok for probes and mars missions that stay in Earth orbit for a limited amount of time, but a BIG no-no for all those NERVA space tug plans they had.

Anyway, if you look at numbers, a NERVA isn't horribly better than chemical rockets. IF you place an orbital fuel depot and a half-decent space drydock where you assemble the spacecraft with a Canadarm or the bots they sent on the ISS some time ago you can do more or less anything a NERVA-equipped spacecraft can do without the above risk.
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:iconghostbirdofprey:
GhostBirdofPrey Featured By Owner Apr 15, 2013
You describe it like nuclear reactors are accidents waiting to happen; if crew safety is a concern bear in mind a number of failure modes for chemical rockets could result in a vehicle destroying explosion, and are probably just as likely to happen. Luckily for people on the ground, you aren't likely to ever see a nuclear thermal reactor in the atmosphere since they don't have the requisite thrust to mass ratio to lift themselves off the ground, and the atmosphere will block the radiation. The big reason you don't like a reactor melting down is the fallout generated; again, not as big of problem in space, and if your engine fails in transit, you're likely already going to die from running out of supplies after careening out into the void.

Yes, there are safety concerns, but they aren't any more insurmountable huge than other rockets or ground based nuclear reactors or anything else. Also, there are designs for both ground and space/engine based designs that use fuel elements that become less fissile as they heat up making it impossible to melt down; the irony is fears over Three Mile Island happening again makes it hard to authorize a power plant that CAN'T have that happen.

The question of efficiency depends on whether you can build one where the reduced propellant mass makes up for the increased engine mass (It has a higher specific impulse (=uses less fuel) and thrust than conventional rockets, but fissile material is dense and heavy and shielding is dense and heavy. If they could shave the mass, nuclear rockets would be better. There's also other alternatives, several electric propulsion designs show promise.
===
I was mainly speaking to the ignorance and paranoia of the masses. Nuclear anything is something evil and irrationally dangerous and could destroy the world. Most people think a nuclear power plant could explode like and H-bomb and it's only good fortune that one hasn't, and the THREE nuclear accidents (only one of which was a total meltdown) somehow cement the view of the danger of nuclear everything in the minds of people while hearing about refinery explosions and oil spills in the news doesn't do the same about other energy sources. As I said, there was lobbying to keep an RTG that produces minimal radiation from being put in space because radiation is dangerous, totally ignorant to the existence of solar wind and cosmic radiation.
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:iconbobafetthotmail:
bobafetthotmail Featured By Owner Apr 18, 2013
No. I just pointed out that a NERVA is basically a smallish nuclear reactor with only a partial shield and limited redundancy, with relatively temperamental reactions as any device that flash-vapourizes cryogenic propellants (rocketry is full of spectacular failures), whose main (and only) cooling is propellant and lacks an internal coolant pool like land-based reactors that even if "standing still" is going at more than 7.6 km/s as anything else in orbit.

Saying it is safe as a land-based powerplant with a full half-meter metal shield (and concrete) plus at least triple-redundant cooling systems plus a safe-ish containment vessel of concrete ready to catch it if it melts down, plus enough coolant in it that it can be left without any cooling for a couple days before it starts having issues is frankly wrong.
On a tangent, all this safety has a price, Three mile Island wasn't a major accident, but ended up costing a lot as both lost revenue and clean-up costs.
It's these ridicolous costs that are killing uranium-based nuclear designs, as they simply make no more economic sense after the need for plutonium (for nukes) dropped dramatically. The future of nuclear is either with Thorium or back to lab-only breeder reactors.

Back to topic, there is "safe nuclear" and "less safe" nuclear. NERVA is less safe. It's the difference between a mono-cycle and a tricycle.
It's remarkably safer than that concept they had of atomic-powered bomber (with a smallish nuclear reactor onboard), and the other thing called Project Pluto, a nuclear-powered airbreathing missile, but does share some of the drawbacks.

Radiation generated by it is harmful for other spacecraft (as it is neutron radiation, while cosmic and space radiation in general is mainly charged particles and a shield that stops one does not stop the other), if it goes rogue or whatever it can destroy satellites or kill crews of other vehicles/stations by just passing at less than a few km from them (think of how dangerous docking maneuvers become). And again if it falls down, you better hope it ends somewhere in the Pacific or you will have to create a big exclusion zone.
It also makes a pain any repair in the general area.

Efficiency is basically down to how much power the engine can generate. In their case it hits a upper limit as the highest tempt the care can go without melting, while the best models that were still on paper (particle-bed kinds) using the best fuel (hydrogen) can provide around 9 km/s of delta-v (vs the 8 km/s of the real ones), the theoretical upper limit is 12 km/s. To do better you have to design liquid-core and gas-core nuclear thermal rockets, that are even more temperamental and dangerous.
That delta-v is easily in the range of conventional chemical rockets, if you make two stages, and the total vehicle mass would be around the same since NERVA's are pretty heavy and you cannot really sidestep that so easily.
So yeah, you use less propellant, but not a lot less, and you add risks you would not have, and costs and complexity.

Imho, they were a dead end. Cool but not practical. Project Orion (pulsed nuclear propulsion) on the other side, it was much more interesting, if a bit sketchy in its ability to survive its own propulsion system.
The same question remains for most engine designs with enough power to go anywhere in less than years.

Btw, have a look at [link]
it's Atomic Rockets, a great site to learn the ropes of well, rocketry.
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:iconsmpritchard:
SMPritchard Featured By Owner Feb 12, 2013  Hobbyist Digital Artist
Unfortunately, that's very true. There's a lot of ignorance in America about nuclear technology.
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:iconkellkrull87:
Kellkrull87 Featured By Owner Jan 26, 2013
''but had we built a few of these, we might have already had a few Lunar and Martian bases by now'' actually, had Nixon not derailed the Space program after Apollo, in 1972-1974, it was NASA's plan to be on Mars by 1980-1981, have a permanent base by 1988 and maybe the first children born on Mars by 1992-1993.
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:iconsmpritchard:
SMPritchard Featured By Owner Jan 26, 2013  Hobbyist Digital Artist
Indeed. He's why the NERVA nuclear rockets have sat abandoned on their test stands for over 30 years out in Jackass Flats. The rockets were pretty much ready to fly, all they needed was a vehicle and a mission. Although, recently there has been talk of NASA re-starting its nuclear rocket research program. I hope very much that's true.
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:iconkellkrull87:
Kellkrull87 Featured By Owner Jan 26, 2013
Actually, I dont know if you've heard but in about 2015, a new firm called Deep Space Industries Inc. will launch a series of prospecting spacecraft to determine when we will be able to harvest metals and water from near-Earth asteroids within a few years after 2015.

Here's the link: [link]
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