Update on Project Prometheus

Aglassis writes "It appears that NASA is not backing down from their nuclear space initiative. Project Prometheus has recently started a new web page (under JPL) and NASA is finishing up a period of public comment (last session today). Currently Northrop Grumman is contracted to begin preliminary design of the spacecraft until 2008 for NASA (the reactor will be built by the Department of Energy's Division of Naval Reactors--the folks who control all US submarine and aircraft carrier nuclear reactors). Early specs are that it will be 60 meters long, have a 30,000 kg mass, use a 100 KW reactor using Brayton cycle gas turbines, be powered by ion thrusters with a 7000 second specific impulse, and have a science payload of 1500 kg. Early mission plans for Prometheus 1 (Jupiter Icy Moons Orbiter) indicate that the spacecraft would orbit Callisto, Ganymede, and Europa individually, and perhaps have a lifespan of about 20 years."

Comments

Brayton cycle

[worst_name_ever]

Interesting that they would pick a Brayton cycle power generation scheme. Since it's open-loop, that means you limit the lifetime of your vehicle to however much working mass - not reaction mass, that's probably xenon in this case - you have on board. Of course the limiting factor might in fact be reaction mass after all, in which case it actually makes sense to have an open-loop reactor and reap the benefits of a simpler system.

Disclaimer: I am not a rocket scientist.

ahhh they stabilized it

[Anonymous Coward]

So they finally figured out how to stabilize naquandria...

JPL

[tyleroar]

Project Prometheus has recently started a new web page (under JPL)

Wow. Am I the only one that thought the JPL must be some license agreement like the GPL, and the wondered why the hell a web page needed to be released with a special license?
Jet Propulsion Labratory

Re:Oh great

[Travoltus]

"Prometheus Nuclear Systems and Technology will focus on enabling NASA missions by researching and developing nuclear sources that will provide power to innovative scientific instruments and robotic systems, large and small propulsion systems that run on electricity and high-speed communications systems. The nuclear power sources would allow us to extensively explore our closest celestial neighbor, the Moon, as well as Mars and other destinations. Eventually, these power sources would support human explorers as they travel through space and explore other worlds.

The first proposed mission within Prometheus Nuclear Systems and Technology would be a mission to Jupiter, the Jupiter Icy Moons Orbiter (JIMO), which represents a new class of mission capabilities far beyond those possible with current power and propulsion systems. Powered by a space nuclear reactor and propelled by electric ion engines, the spacecraft would make up-close, long-term orbiting visits to three of the solar system's most intriguing moons- Europa, Ganymede, and Callisto. Beneath their icy surfaces, these moons may contain oceans of water that could have provided an environment that may have harbored life."

http://prometheus.jpl.nasa.gov/index.cfm?pageL1= mi ssions

Beats the heck out of me what that has to do with militarizing space. Besides, IMO, nuclear power is a lot less environmentally dangerous than other power sources except maybe solar energy (which might not work when you're x billion miles from the sun).

Re:Oh great

[QuantumRiff]

what do you think absorbs the readiation from the sun? (hint, its our atmosphere) that big ball in the sky that is the solar systems largest reactor (although its fusion, not fission). Honestly, do you think it's light that heats the earth? no, it radiation. Any radiation from a little spacecraft up in space is miniscule!

Project Orion was cooler, though

[armed ahmed]

Of all the atomic propulsion systems, project Orion is the one that struck me as 'reasonable', despite the atmospheric miniature nukes. The sheer payloads that it would enable make Orion the number one option for human spacefarization.

That said, I'm happy it never really materialized. Having a universe with a human population spreading effectively in it summons an eerie image on a spherically expanding brain-tumor to my mind...

...anyone interested in nuclear propulsion and the most avant-garde of rocketry, read about "Project Orion" if you already haven't.

http://isbndb.com/d/book/project_orion.html

Re:The thing to do with Uranium

[crypto55]

In case you didn't realize, Uranium is the 8th most common material on the planet... Taking a few tons off of it won't do any good. There's enough uranium to last the damn planet for the next 2000 years at least. Don't argue with me, I researched the damn thing two months ago. :)

Re:Thank god

[puzzled]

Coal is somewhere between one and thirteen parts per million Uranium. You can google and check the math but these numbers are not out of line:

We put twenty five *tons* of bomb grade Uranium 235 into the air each year with our current coal consumption. U235 is .72% of naturally occuring Uranium which means we're putting up about 3,500 tons of U238 as well. U238 which gets hit by neutrons from cosmic rays becomes ... Plutonium.

http://greenwood.cr.usgs.gov/energy/factshts/163 -9 7/FS-163-97.html

Don't tell any tree hugging antinuclear activists, but our most common form of electricity production will *always* produce more radiation than the most horrific nuclear fuel accident. Changes the picture a bit, doesn't it?

Its all cold war BS that we don't have nuke powered space vessels to take advantage of the 1,000X energy density improvement over chemical fuels. I hope this comes to an end soon ... I want fast Mars shots before I'm too senile to appreciate them.

Re:Thank god

[SidV]

Thank Jeff that when you take a small mass of radioactive material that gives off lethal amounts of radiation and spread it over a large geographic area you cannot get a lethal exposure.

In other words the background radiation of the debris area was less than the natural background radiation of natural Uranium rich areas like Western Africa, or in fact many parts of Canada, which have higher radiation levels than the debris area.

Gaseous Core Nuclear Reactor Rockets

[serutan]

On a related note, a few words about nuclear rockets. Back in the 50s and 60s some people, mostly science fiction writers, fantasized about nuclear powered rockets. In the 60s there was an actual prototype engine called NERVA. The idea was simply to use the reactor as a heat source to superheat a gas which would shoot out as rocket exhaust. The main drawbacks were the weight of the reactor core, the maximum temperature of about 3500 degrees C, and the radioactivity of the exhaust.

Here's a really interesting article that describes a design for a 100% reusable, non-polluting nuclear rocket based on the Saturn V form factor, capable of lifting 2 million pounds of cargo into orbit and returning to a soft landing. Just like in the old sci-fi movies. The design involves a gaseous core reactor, sometimes called a "nuclear lightbulb." It consists of a quartz bulb containing a cloud of uranium gas such as uranium hexafluoride, confined the center of the bulb by a buffer gas swirling around it. By adjusting the movement and pressure of the buffer gas, the compression of the UF6 can be finely regulated. When it is compressed to a critical state it heats up to about 25,000 degrees C, glowing intensely in the ultraviolet. Liquid hydrogen propellant pumped around the outside of the quartz bulb absorbs the ultraviolet light, becomes superheated, and shoots out of the nozzle. There is no leakage of radioactive fuel and no irradiation of the hydrogen. Completely clean burning. Such a rocket could burn for immensely longer times than any chemical rocket, providing the speed to get a manned mission to mars in a couple months. And not a skimpy mission, a spacious vehicle carrying 1000 tons of equipment, supplies and radiation shielding. Building a rocket like this wouldn't require any far-fetched technology, just some dedicated engineering.

I have never been a fan of nuclear reactors, but this thing sounds really good to me. The gaseous core has tremendous safety advantages over a solid core. The criticality of a cloud of gas is much easier to control and is to some extent self-regulating. For example, the problem of "hot spots" would not exist, because in gaseous form any part of the UF6 that overheated would expand, losing pressure and quenching itself instantly. The author describes several safety features, both active and passive, for letting the gas depressurize into a storage container extremely fast. Even if a gas core nuclear rocket exploded in the atmosphere, it would release a small fraction of the amount of nuclides from a single 1950s H-bomb test.

NASA must have told Bush there's oil on Titan!

[mbkennel]

that's right, George, there's rivers and rivers of LIQUID HYDROCARBONS down there, and America's got the mineral rights!