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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."
It's spelled Northrop Grumman.
I hope that after I die the one word people use to describe me is "resurrected."
Actually, funding for JIMO (Jupiter Icy Moons Orbiter) has been cut.
"Does it run Linux?" ... yes, it does. The onboard microcontrollers on the craft will run the uCLinux kernel, with Gentoo userspace. I have no idea what the boxen back at NASA supporting this will run though.
... I for one don't want to welcome our angry alien overlords after they get sick of the crashes :-)
It's a pleasant thought that the first software that aliens might encounter from Earth won't be from M$
"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.
= mi ssions
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
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).
--- Grow a pair, liberals... stop letting the Republicans bully you!
There are open and closed versions of the Brayton cycle engine.
=Smidge=
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!
What are we going to do tonight Brain?
We used it in WWII.
And Iran would be pacifist if we never got involved in their history. They had a moderate government with some elements of capitalism. But then the USA decided to help Hussien, we sold him all the arms he needed to attack Iran for over a decade. And we let the Shah get expelled, for a very rigid Kohmeni.
Rosco: "If brains were gunpowder, Enos couldn't blow his nose."
Light is, of course, radiation.
You are 100% correct. The large panels are radiators to dissipate excess heat. Large radiators are a standard feature in designs for space-going reactors, since the conversion from thermal energy to electrical energy is far less than 100% efficient.
Our local observatory (with live night-sky camera) is Gummint-funded. This leads to some interesting effects.
Much of their computing equipment has been scrounged - and doesn't appear on any equipment manifests - because there was no budget for it. They have a Pentium-90 driving (pointing) their main 'scope with a backup P-90 literally sitting on the next shelf in case it dies.
The few pieces of gear that they do get grants for are typically extremely fancy. On the rare occasions when ThePowersThatBe say "yes, you can have a computer to process the incoming images," then the cost of that actual computer system and absolutely nothing else is almost immaterial as long as it fits certain criteria.
So... in the room to the left of the one housing the P-90 sits a you-beauty glow-in-the-dark (well, not literally, it would cause backscatter) state-of-the-art box with double overhead ThermalTakes and all the trimmings. Just one. And I bet they crammed memory and disks into that baby's purchasing spec until the chassis groaned under the weight.
When Mark Shuttleworth gave his amazing talk at LCA2005, one of the things he mentioned was that the Yanks didn't want their astronauts (also going up in the Soyuz with Mark) flying to Baikonur in a rattly old Tupelov transport lest it unexpectedly drop out of the sky en route, but rather than come out and say so directly they came over all clever and simply pointed out that NASA regs forbade their astronauts to travel without seatbelts, which they knew the Tupelov wasn't fitted with. This was a mistake. On the day, the astronauts were marched out to the Tupelov, and aboard - and into a minibus in the cargo bay, where they sat and wore the minibus's seatbelts for the duration of the trip.
BTW, when the video DVD from LCA2005 gets published, bend heaven and earth to get yourself a copy. It's well worth-while for Mark's presentation alone ("Welcome to Khazakstan!"), and there are many other excellent presentations on it (Keith Packard explaining the sport of Window Hurling, for example, or E'dale demonstrating how to collapse a penguin's skull).
The point in that story which I wanted to use as an illustration here was that the minibus wasn't put aboard the transport for the astronauts' benefit. There was a budget for flying the Tupelov - pilots, fuel, landing fees and so on - but no budget for getting from the airport to where they were staying. So the van (which fell under the base's budget, so was financially covered) was fuelled up and driven aboard the Tupelov for use as a taxi while the transport 'plane was prepped for the return flight. In terms of working around bizarre regulations, NASA or not, the Americans really were amateurs playing in a professional field. (-:
Got time? Spend some of it coding or testing
The move to fission is driven by a desire to get more power (even a large RTG will only produce a few hundred Watts, versus the kilowatts they expect to get from a reactor). I don't know exactly what the trade-offs are with using Brayton cycle vs thermoelectric (or thermionic) conversion. The Russians have flown a number of thermionic nuclear reactors (the Topaz series), and they seemed to work fairly well. I suppose it's possible that Brayton cycle reactors are more efficient than thermoelectric/thermionic conversion. But even if you assume a (highly unlikely) 90% conversion efficiency, a 100kW reactor would leave you with 10kW of thermal energy to dump. At this point it's probably worth noting that even the most high-power satellites we currently fly (the Boeing 702 comm-sat) operate on a mere 15kW of power. So you're talking about being able to radiate as much energy as most satellites generate in total. And as I said, that's based on some pretty optimistic assumptions about the efficiency of the Brayton cycle.
He knows, but a baryton engine requires(this is what the grandparent assumed) a working fluid to get the heat energy of the nuclear reactor to power a turbine.
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. :)
Due to financial difficulties, the light at the end of the tunnel has been turned off.
Because there ain't no way the Bush White House is paying for this.
Actually, the Bush administration explicitly gave the go-ahead and requested funding for Project Prometheus. I dislike most of what Bush does, but this was one of the few things he did that I supported.
Of course, this made anti-nuclear folks like Bruce Gagnon quite spastic.
Here's Nasa's close Brayton Cycle unit0 mason. html
http://www.grc.nasa.gov/WWW/RT2002/5000/549
Only 24% of the thermal heat from the reactor is converted to electricity, but then that's probably pretty good for a closed cycle unit.
No good heatsinks in space.
Starman97@Gmail.com (bring it on spammers)
Well atmosphere and the Van Allen belts which scoot much of the dangerous radiation around us (Earth).
Of course those outside of our atmosphere and Van Allen belts are exposed to massive amounts of radiation, and without protection they would die.
As to radiation from a Nuke in Space.
1. Nuclear reactors don't explode, to explode (i.e. nuclear bomb) requires particular materials in a very specific configuration. A reactor does not meet the requirements. What you would end up with is a large hot radioactive mass.
2. 100 Miles away wouldn't make much of a difference as there is nothing to stop the radiation in the interim (Vacuum of space), so you just loose exposure geometrically as the sphere of radiation expands. Regardless radiation exposure is kind of a binary system (for you geeks) enough to kill you is enough to kill you. Adding more does not kill you more. Since deep space has enough radiation to kill you the addition of more is irrelevant. Unless it is of a type to penetrate the shielding. That type is already emitted by the Sun, and is not particularly emitted in high numbers from runaway reactors.
As to putting massive amounts of radiation into space. Well we have the Sun which is a big massive nuclear reaction dumping huge amounts of radiation. The sun is 1 million times larger than the earth. Therefore any nuclear reaction we put into space by definition is going to be less than 1 millionth the size of the sun, as a reaction 1 millionth the size of the sun would be the size of the entire earth, and any nuclear mass we put up is going to be less than that. In fact it would be less than 1 millionth of 1 millionth the size of the sun. And this puny mass would be in the solar system which is even bigger than the sun (By definition) in fact it's a lot bigger than that, much much bigger. So long as it's outside of orbit of the earth and doesn't come crashing down on East Philadelphia it would be of so little significance it wouldn't matter.
But regardless. whether it's buried in the ground of Gabon, or floating in space it's just a matter of position. It's still floating around in space, and still emitting radiation. Putting it on a deep space probe just moves it from one plce to another.
are you implying that a 100kw fission reactor in orbit presents an exposure concern to personnel? i hope you are joking. assuming average prompt gamma ray energy is 1 Mev, the reactor has NO shielding, 1 Ci of a 1 MeV gamma ray point source produces an exposure rate of 1R/hr at a distance of 1M, all of the energy is emitted from a point source, and the reactor acts as a 100,000 Ci point source(this should be conservative, someone with more knowledge might upgrade me on this?), then(neglecting backscatter buildup): DR @ 1m = 100,000R/hr DR @ 10m = 1000R/hr DR @ 1km = 0.1R/hr DR @ 100km = .01mR/hr
365 days * 24hr * .01mR/hr = 87.6 mRem(assuming 1 as a QF, i can't recall the QF for a 1MeV gamma flux right now).
assume the reactor and craft present 1 tenth thickness of shielding(should be conservative): 8.76mrem
assume the atmosphere presents 3 tenth thickness of shielding(again conservative): .00876 mRem
this craft in orbit(realizing it will not remain there) would, conservatively, increase the average persons natural radiation exposure by less than one thousandth of one percent.
this is simplistic but AFAIK conservative.
Embedded systems use a device called a watchdog timer. Basically, it counts down from, say 2 minutes, then reboots the computer. The programs running on the computer need to continually reset the timer back to the 2 minute mark. If the computer locks up, the timer is never reset. It will count all the way down and reboot the computer.
"I'm not impatient. I just hate waiting." - My Dad
I thought you might like to know that nucleotides are those cool little thingies in your DNA that make up the genetic code.
The current plan is for fission reactors to be used outside of an earth orbit. Earth is close enough to the sun that solar panels are still a good choice for energy, so reactors aren't needed. It's on the deep space probes, like the Jupiter Ice Moons Orbiter (if it ever happens) where this becomes useful. It could also potentially be used on a manned Mars mission since the extra power it produces could be used to run an ion propulsion system.
The image was done in LightWave 5 roundabout 1996-1997. The Omega cruiser was done by Matt Stetson, and the Starfury mesh was done by Mark Kane. LightWave was the same program used to do the show as well.
Oh yes, and I know this because I created that image. :)
My old site with a bunch of Babylon 5 renders is still up, although much of it was lost several years back.
A good point. In fact, thermal design for spacecraft (at least at the preliminary stages) is typically carried out under the assumption that all of the electrical energy not leaving the spacecraft as RF radiation is converted into thermal energy.
The two energy expenditures I can think of that don't yield waste heat are the propulsion system (ideally), and the radios (again, ideally).
Unfortunately, both of those items are less than ideal. It's not uncommon for a spacecraft transponder to be on the order of 20% efficient (or worse). Likewise, the ion propulsion systems they are planning on using for Prometheus have an electrical->thermal conversion efficiency of around 70-80%. Which for a 20kW thruster (e.g. the proposed NEXIS thruster) means 4kW+ of waste heat.
Of course, I expect it would be possible to use a significant portion of that to heat the propulsion fuel.
The current proposals for Prometheus involve nuclear-electric propulsion rather than nuclear-thermal propulsion. I don't believe that heating the propellant in a NEP system helps (although I'm not really a propulsion expert, so I'm quite prepared to be corrected on this).
And Iran would be pacifist if we never got involved in their history. They had a moderate government with some elements of capitalism. But then the USA decided to help Hussien, we sold him all the arms he needed to attack Iran for over a decade. And we let the Shah get expelled, for a very rigid Kohmeni.
I think you are a bit confused about the particulars, though your general point is correct.
Act I: Iran has a popular, secular, western-educated leader, Mohammed Mossadegh. Unfortunately this leader happens to brush American and British governments the wrong way, to the point of actually nationalising local oil companies (shock ! horror !)
Obviously our luminaries of freedom and democracy can not tolerate such an attack on western businessmen's rights. So they organise a coup to get rid of Mossadegh and put the Shah into power, leading to a few years of a rather brutal dictatorship. That's Act II.
Act III: At some point the Iranians got really pissed about it and started a revolution. This revolution was driven by two main forces: socialist intellectuals and islamic fundamentalists. As soon as the Shah was overthrown, the islamists simply eliminated the socialists and used their fanaticised support base to crush upon any kind of dissent.
Just a bit later, Saddam launched a war against Iran for seemingly no reason - but with thorough US and western backing, at least in the beginning (hey, he's against the Mollahs, so he's a good guy, right ?). One million dead. Only when reports of atrocities emerged (gasing of Kurdish populations) did the west begin to reconsider their support for Saddam.
Iranians hate the US, period. But this deep resentment against America was not instillated by their government - only exploited as a way to strengthen their power (since the Iranian government is the most outspoken opponent of the US on the world stage, anyone who dissents with the Iranian government can conveniently be called an agent of the US). Iranians have good reasons to dislike the US. By removing a moderate, popular government from office out of short-term considerations, they opened the way for a much more brutal, oppressive and dangerous regime in the end.
You'd think they'd learn.
Thomas
It's much slower than traditional orbital transfers, but so much cheaper that it's worth using. It's already been used on SMART and Galileo:
http://www.sciencenews.org/articles/20050416/bob9. asp (even mentions using it for Jupiter moon exploration!)
http://www.ufoindia.org/news_intsuperhighway.htm
PHEM - party like it's 1997-2003!