NASA Selects Contractor for First Prometheus Mission to Jupiter

[bobvanx]

SNAP10A video and the whole Boeing Prometheus website is taken away.<br /><br />Sorry, I certainly could have sucked it down if I'd known they were going to do that.

 

[bobvanx]

hee hee!<br /><br />here, paste this into RealPlayer's "Open Location" <br /><br />rtsp://video.boeing.com/external/events/snap10200.rm

 

[bobvanx]

>I am not trying to be sarcastic<br /><br />I appreciate that. I had the opportunity to train someone today that we could be in disagreement yet still work nicely together. She failed to grasp it, and kept trying to convince me she was right. She also kept waiting for me to get angry. Neither was likely.<br /><br /> />Any program that lasts more than a decade, history shows, is very unlikely to survive politically long enough to do anything.<br /><br />?? The best analogue I know of for SNP is the wonderful job our submariners do. That's a program that is decades old.<br /><br /> />In what way is space nuclear power related to getting more people into space?<br /><br />Access to reliable, high levels of power in dangerous environments (where there is no hydro or oil or natural gas) will make it possible to colonize the Moon, Mars, and any other rocks we care to.<br /><br />We can manufacture nearly anything from nearly anything: shelter from dirt, food from waste, and so on, but the one thing we must have is a reliable source of power. The sun is great, you betcha, and one day we'll all realize that. But we've got to get to that point, first. Until then, nuclear plants are what we need to build Mars Colonies.<br /><br />A Moon colony could very easily be solar, and I hope it will be. Build a robot to drive along, transforming regolith into solar cells, even at 12% efficiency, and before you know it you've got terawatts of capacity. Spin up a nice big flywheel on magnetic bearings for energy during the night, or set up beaming towers to shuttle the energy around. And then we'll realize that we can beam that energy back to an energy starved Earth. Maybe before global warming and the burning of fossil fuels does as all in. Oh wait, we're already 30 years too late for that. <br /><br />The problem is that the solar people aren't in power, and won't be for the forseeable future. So hitch your dreams onto the cart that's already moving, push for more funding (you hopefully are alrea

 

[bobvanx]

>Are you talking about solar thermal or concentrated solar photovoltaic?<br /><br />With a little clever design, you can have both. As well as a giant radio antenna.

 

[scottb50]

It's very true the father you are from the Sun the less solar power available, but with efficiency of 40% and higher in the offing, and promising future improvements probable, solar still makes the most sense. Use the electricity produced to hydrolize water to power fuel cells and recycle the exhaust water. Much cheaper and lighter than Nuclear with infinitely available sunlight and water as long as it is a closed system. <br /><br />When needed Hydrogen and Oxygen could also be used in thermal engines for initial boost and getting into and out of orbit at a destination. All you need to carry is water, which you need to carry anyway if you have people. A secondary benefit would be using the water to protect the crew from radiation during long trips. <br /><br />The only thing Nuclear could do is provide electricity, if used as an engine it would either take massive amounts of propellant, mostly to keep the core from melting, or power for ion engines that wouldn't provide the amount of energy required to brake into orbit or escape from orbit. <br /><br />Why would you need 200kw of power anyway? That seems like overkill on a vehicle that would be dispatched on such a trip. I believe the Shuttle operates with about 7,000W.<br /><br />I think I'll wait for fusion though for advance propulsion.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[najab]

><i>Why would you need 200kw of power anyway? That seems like overkill on a vehicle that would be dispatched on such a trip. I believe the Shuttle operates with about 7,000W.</i><p>You're completely missing the point. The question you should be asking is: "What can we <b>do</b> with 200kW?" The answer is "A lot!" For one, you can run all your instruments all the time, most probes these days have to alternate measurements. Also, you can carry high-power instruments that you would never consider otherwise: MARSIS is carrying a radar that can penetrate up to a kilometre - imagine cranking that up from a few hundred Watts to a couple thousand.<p>The point is that having more power available allows you to do more. The two limiting factors in robotic spaceflight are power and mass - JIMO's gonna have plenty of both to go around.</p></p>

 

[halman]

najaB,<br /><br />Sometimes, I really get tired of the battles staged between proponents of differing tecnologies. No one seems to remember that everyone benefits from the advancements made in a given field. It may take a while for those benefits to become apparent, but they do. Nuclear is a big money field, full of physicists with DoD experience, looking for a way to utilize huge amounts of power in a small package.<br /><br />When they figure it out, it will help to get people off the planet. The more people who get off the planet, the greater the demand is going to be for non-nuclear power, because solar is free. The greater the demand for non-nuclear, the more money will pour into solar technology.<br /><br />Technological advance is a synergistic process. What is learned in one field is often found to have tremendous impact in another. The only thing that slows it down is fighting the advance of technologies different than the one that you favor. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[SteveMick]

Yurkin<br /> I beleive That I already won this argument in principle and was too lazy to do the requisite searches. I recently found the site for the concentrator cells and posted it. I remember being told they did not exist.<br /> The mass of the inflatable concentrators built so far is what I haven't yet found and I would appreciate help with that. <br /> The question of the minimum mass for a concentrator is a fascinating one and I hope more clever minds will engage that problem. There are possibilities like light nets, Fractal architecture and infalation insitu-form with degradable elements(my invention).<br />More later. <br />Steve

 

[najab]

><i>infalation insitu-form with degradable elements(my invention).</i><p>Sounds interesting, what's the patent number or do you have links to information on your prototype?</p>

 

[SteveMick]

Yurkin<br /> Thanks for your interest if sincere. If it was a gotcha then to an extent you got me in that I want still to keep my claim for possible patenting in the future so I deliberately claim it as my invention even though I haven't pusued legal aspects. <br /> Invention can mean originating and writing about the design without patenting it. I first wrote about the concept in "Proceedings of the 22nd Space Congress" in 1985 and have developed it somewhat although not to the level of prototype (laziness again I suppose), but the concept is straightforward: inflation of the antenna or concentrator is followed by the hardening of some parts by exposure to UV light and or heat and pressure and finally the parts not hardened are made of plastics that are made to degrade in UV light(developed to help landfills) and these gradually decompose leaving the hardened material behind. The first part has been developed and is used in one of the Glenn designs for strut deployment. Adding degradable elements allows the final mass of the concentrator to be much less than its initial LEO mass. It also allows the possibility of light nets since they can be encased in degradable plastic and thereby survive launch and deployment despite their extreme fragility. It also allows struts to be extremely low in mass for the same reason. The idea relies on plastics that are currently available so there should be relatively few develpment problems.<br /> To argue that solar concentrators cannot greatly exceed JIMO in specific power at Jupiter requires allowing for no development of advanced concentrators, an activity which will take far less time and money than the JIMO system and indeed could be done for the 400 million that will produce a preliminary design(paper) for JIMO.<br /> Remember that a patent is not proof of the utility of a device, but rather its novelty and that it doesn't violate Physics. Its ironic that the JIMO powerplant requires such time and treasure to develop and yet bec

 

[yurkin]

Hi Scott<br /><font color="yellow"> if used as an engine it would either take massive amounts of propellant, mostly to keep the core from melting,</font><br /><br />I’m not going to deny the problems facing thermal propulsion. Certainly a NFu-TP engine “nuclear fusion thermal propulsion” would be ideal but we have to start somewhere. First solar electric, then nuclear electric, then nuclear thermal, then fusion thermal propulsion with each system building off the one that came before it. The Wright brothers didn’t start out with a B-52.<br /><br /><font color="yellow">or power the ion engines that wouldn't provide the amount of energy required to brake into orbit or escape from orbit.</font><br />That’s not true it just takes a lot of time, but it’s a very efficient system. It’s a trade off of time for energy, just look at Smart-1.<br /><br /><br />Steve<br /><font color="yellow"> Solar electric could be used and with 25 times greater power available near Earth as opposed to JIMO, would not take 2 years to escape Earth orbit.</font><br /><br />Yah no kidding it would take a lot longer. The craft would be many time heavier so it would take a longer. The increase of energy cannot be directly transferred into velocity. You could increase the voltage to engine which would require more fuel and decrease the efficiency, and life expectancy of the engine. Or you could add more engines and fuel. If you did this right it might end up being just as fast, just a couple times heavier.<br /><br /><font color="yellow"> STR's on the other hand operate at the efficiency of nuclear thermal or better and are potentially quite useful for travel beyond LEO</font><br /><br />They have a lot of potential for powering lunar bases and orbital platforms. But building one for Jupiter where the energy levels are 25 times less isn’t practical. And the more energy you need the less practical it becomes. Solar thermal propulsions that requires huge amounts

 

[SteveMick]

Yurkin writes: "Steve <br />Solar electric could be used and with 25 times greater power available near Earth as opposed to JIMO, would not take 2 years to escape Earth orbit. <br /><br />Yah no kidding it would take a lot longer. The craft would be many time heavier so it would take a longer. The increase of energy cannot be directly transferred into velocity. You could increase the voltage to engine which would require more fuel and decrease the efficiency, and life expectancy of the engine. Or you could add more engines and fuel. If you did this right it might end up being just as fast, just a couple times heavier. <br /><br />STR's on the other hand operate at the efficiency of nuclear thermal or better and are potentially quite useful for travel beyond LEO <br /><br />They have a lot of potential for powering lunar bases and orbital platforms. But building one for Jupiter where the energy levels are 25 times less isn’t practical. And the more energy you need the less practical it becomes. Solar thermal propulsions that requires huge amounts of energy just isn't going to work even only as far as Mars. "<br /><br /> Yurkin as I said, the constraining factor on STR's is the concentrator. The specific power can easily be in excess of 10KW/kg for current inflatable concentrators at 1 AU and if the 1KW/kg concentrator cells are used for electrical power generation, the specific power is 1.1kw/kg at 1 AU. JIMO by contrast has a projected mass of 50,000lb/100KW or a specific power of 500lb. per KW. If 1/500th the power is available for JIMO and if it uses the same elec. propulsion system, it will have 1/500th the rate of acceleration. The need to have 100KW at Jupiter means that potentially 2500KW elec. could be generated from the sunlight provided by the concentrator at 1AU if the mass penalty of excess capacity at Jupiter is deemed worth it. Larger elec. engines could be used, but I beleive solar thermal is the better choice for LEO to escape-I was merely making a point.<br />

 

[mrmorris]

<font color="yellow">"Because solar concentrator mirrors which are very low mass (more than solar sails but not more than 2 or 3 times as heavy as them), gather the energy, the overall mass even including the radiators that double as mirror supports, should be around 2 kg/KW electric. "</font><br /><br />Where does the weight of batteries come into this figure? A Jupiter orbiter will be in the shadow of the planet and/or one of the moons for considerable periods of time. Using SMART-1 as an example -- on occasion it was in the shadow of the earth for periods of ~2.5 hours, and this strained its ability to survive. Conservatively, a Jupiter orbiter would likely have to survive periods of />15 hours (someone more adept with orbital mechanics might be able to pin this down better). To provide <b>full</b> power of 200kW for a 15-hour period would require batteries capable of supplying 3000 kW-hours of power. Using lithium ion batteries (Typical energy density: 63.6 Wh/lb) for this would add about 47,000 pounds to your Jupiter probe.<br /><br />Even halving or quartering the available battery power will still leave you with a considerable mass bill for powering your probe in the dark. Every time you reduce the fraction of power available with batteries, you reduce the amount of science that can be done by the probe which in shadow. A considerable amount of power is necessary just for keeping the components warm enough to survive. <br /><br />Also, I believe the 15-hours is fairly conservative as well, so the mass picture is likely worse than what I've stated.<br />

 

[scottb50]

Why do you need batteries when you can hydrolize water and use the Hydrogen and Oxygen in fuel cells? Over and over again. <div class="Discussion_UserSignature"> </div>

 

[bobvanx]

Maybe I've stumbled across one of the assumptions, that I for one, kept missing.<br /><br />Solarthermalphotowhatever is a great idea and will be a fine tek in the future <b>for in-space power needs</b><br /><br />Nuclearthermalfissionwhatever is a great idea and will be a fine tek for planetary operations.<br /><br /> /> The only thing that slows it down is fighting the advance of technologies different than the one that you favor.<br /><br />yes yes YES!<br /><br />Tek rarely gets completely ossified in one manifestation; look at electric motors, powerful ones were developed for autos at the turn of the century but eventually found their way to forklifts and handheld drills. Let's get all these scientists and engineers and politicos doing what they already want to do (build nuclear devices) but have them do it for off-planet applications!<br /><br />here's the arc: NTP or NEP (space applications) then NP for landed operations (Mars Rovers) then for habited volumes (you are all so spoiled by having effectively limitless access to electricity, that some of you can't even imagine the power constraints of a research station. Will the station commander choose to run Greenhouse lights or send emails?). At a critical mass (heh) of habited volumes, people begin looking for a cheaper transport method. Boom! 50% efficiency high-temperature concentrated solar cells are waiting to fill the need.

 

[yurkin]

<font color="yellow">I'd love to see your figures on this as I'm sure you wouldn't just make stuff up.</font><br />I could give it try. You’ve got it fairly messed up.<br /><br /><font color="yellow"> 1 AU and if the 1KW/kg concentrator cells are used for electrical power generation, the specific power is 1.1kw/kg at 1 AU.</font><br />Is this just the weight per pound of the solar cells and concentrator? Nothing else?<br /><br /><font color="yellow">JIMO by contrast has a projected mass of 50,000lb/100KW or a specific power of 500lb.</font><br />Please use some common sense! The whole craft isn’t going to be power supply. There’s the science package, main bus, engines and fuel. Half the weight is going to fuel. Your comparing the whole weight of the Jimo against the weight of the solar panels.<br /><br /><font color="yellow">If 1/500th the power is available for JIMO and if it uses the same elec. propulsion system, it will have 1/500th the rate of acceleration</font><br />I’m not sure that true, I think there’s a little more to it then that, but I might be wrong. Regardless though time is the least critical factor was engineering robotic explorers. Weight, volume, cost and reliability are really the critical ones. It doesn’t matter how long Jimo takes to get there as long as it gets there.<br /><br /><font color="yellow">efficiency of 33% on the overall sys., 833KW of energy goes into thrust.</font><br />No it doesn’t mean that. It would mean that 833kW goes from the generator to the engine. You can’t just magically transfer electricity to thrust. They are two different units.<br /><br /><font color="yellow">For JIMO, the eff. of the elec. prop. engine may be 80%</font><br />A twenty percent drop off between the generator and the engine. If that was the case I’d definitely have a word with the engineers. The nuclear generator onboard Jimo is going to be running at about 30% efficiency depending upon wha

 

[SteveMick]

Yurkin<br /> The question was whether your assertion that a solar concentrator would be "much heavier" than the JIMO power system was accurate and therefore which system could (using electric propulsion since STR's are able to escape within a month or less) reach escape velocity from LEO soonest. A solar power/propulsion system would have far less mass even when 25,000lb. is used for the JIMO powerplant mass. A concentrator that can focus the 330 or so KW thermal needed to make 100KW elec. at 5AU will focus 25 times that at 1AU or 8250KW thermal.<br /> An STR is 33% efficient(ballpark) at turning this energy into enthalpy in the propellent. JIMO has only 100KW available for any propulsion need maximum and yes, there is loss in turning this electricity into thrust as no 100% efficient ion or other elec. prop. sys. exists and it's hard to see how one ever could. However the solar sys. would also have this loss if running electric propulsion.<br /> I'll try to answer each of your points at lunch if work schedule permits, but concentrator mass vs. JIMO power sys. mass is the crux of the issue IMO.<br />Steve

 

[mrmorris]

<font color="yellow">"Why do you need batteries when you can hydrolize water and use the Hydrogen and Oxygen in fuel cells? "</font><br /><br />I've got nothing against fuel cells being used. Feel free to locate the power density coefficient for current-technology fuel cells and figure out how much mass they'd require.

 

[scottb50]

Here's an idea of the mass and basic size of a fuel cell system.<br /> http://www.mhtx.com/media_center/pressrelease36.htm<br /><br />Since a hydrolizer is basically a fuel operating in reverse somewhere around 8-10 pounds per KW. Include the mass of solar cells to provide the power to run the hydrolizer and a 200kw system would still be well less than a third what a nuclear reactor would require. <div class="Discussion_UserSignature"> </div>

 

[backspace]

Entropy.<br /><br />You're going to have to add additional mass for water to put into your hydrolizer. How much, I have no idea. Until you run this system in a zero -g vacuum at appropriate temperatures, the entropic effect on the system is unknown.<br /><br />Don't get me wrong, I like the idea but it seems to me that arguing that this is a viable alternative to NTP without data to back it up serves little purpose.

 

[SteveMick]

mmorris writes:<br />"Where does the weight of batteries come into this figure? A Jupiter orbiter will be in the shadow of the planet and/or one of the moons for considerable periods of time. Using SMART-1 as an example -- on occasion it was in the shadow of the earth for periods of ~2.5 hours, and this strained its ability to survive. Conservatively, a Jupiter orbiter would likely have to survive periods of />15 hours (someone more adept with orbital mechanics might be able to pin this down better). To provide full power of 200kW for a 15-hour period would require batteries capable of supplying 3000 kW-hours of power. Using lithium ion batteries (Typical energy density: 63.6 Wh/lb) for this would add about 47,000 pounds to your Jupiter probe. "<br /><br /> There are many ways to deal with this issue.<br />The first and most obvious is to minimize the time in shadow at Jupiter by carefully choosing orbits. The second would be to arrange the mission so that full power (for radar or whatever) is only used when in full sun. In this way the battery of regenerative fuel cell need only supply the much smaller energy needs of the craft itself and not the radar.<br /> The 100KW figure is IMO an arbitrary number and not based on supplying particular power needs expressed by scientists prior to that figure being mentioned In other words, scientists didn.t say "I need 100KW, but rather they were told they would have 100KW. This always suggested to me that this project came about just to promote the development of space nuclear or cover a black project rather than explore Jupiter. If a solar powered mission were designed, it would need far less power to do the same radar because it would have two concentrators which can double as antennas for radar and could provide high speed data as well.<br />Steve<br />

 

[najab]

<blockquote><font class="small">In reply to:</font><hr /><p>Since a hydrolizer is basically a fuel operating in reverse somewhere around 8-10 pounds per KW. Include the mass of solar cells to provide the power to run the hydrolizer and a 200kw system would still be well less than a third what a nuclear reactor would require.<p><hr /></p></p></blockquote>Eight to ten pounds per kilowatt - that sounds low, but even if it isn't how much will the <b>whole</b> system work out to? You still need to add the mass of the water, solar cells and plumbing. I'm just making a WAG here, but you're probably talking more like a few <b>hundred</b> pounds per kilowatt.<p>By the way, the Russians have already operated 5kW fission reactors on orbit. The Topaz-1 reactors had a core mass of about 320kg and produced anywhere from 5 to 10kW of electricity.</p>

 

[yurkin]

Scott<br />That would never work. You could replace lithium batteries with regenerative fuel cells and that would be a great idea. But you can't use them to replace the power source. If you were to do that you would need a very large supply of hydrogen and oxygen to keep Jimo running for about ten years.<br /><br />If you burnt hydrogen in the fuel cell and you'd generate electricity and water. Then the water is saved and the electricity’s used to convert it back into hydrogen and oxygen. The problem is your not going to end up with a positive net electricity. It will take more energy to convert the H20 back into H2 an O2 then it would get burning them in the first place. If your idea worked it would be an infinite energy machine.<br /><br />http://www.llnl.gov/str/Mitlit.html<br />

 

[bobw]

I thought he was talking about the using fuel cells to replace the batteries. Solar power would convert the water back to hydrogen and oxygen. To get the same power you would need solar cells that give the 100KW + enough energy to generate hydrogen and oxygen to provide the 100KW during the shadow phase of the orbit. I've never heard that idea before. <br /><br />I just don't think solar is practical out there, that's why they want nuclear. <div class="Discussion_UserSignature"> </div>

 

[scottb50]

The amount of water would depend on the specific power needs.<br /><br />http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/electrol.html<br /><br />I would also include the water needed to establish an orbit and boost out of orbit for a return as well as land and depart a destination planet, moon or object, I can't see a nuclear engine doing that without massive amounts of propellant just to cool the system. You would also need enough water for crew consumption and for effective shielding of the occupants for the entire mission. <br /><br />Since you would have to carry the equivelent in water for crew protection and consumption as well as some sort of chemical propellant for establishing orbit and return, the amount needed simply to produce electrical power would be fairly small and the mass usable over and over again. <br /><br />Considering the water is needed anyway if you have people and LHs and LOX provide the highest available conventional ISP, water would require less over all mass when used as a propellant than any other chemical source. Because the same hydrolizers could provide Hydrogen and Oxygen for both uses the only other equipment needed would be cryogenic cooling and storage for propellant, still much less total mass of hardware than a nuclear power plant.<br /><br />Fuel Cells have been run in Space for some time and a hydrolizer is a fuel cell operated in reverse, fluids have been contained and transfered in Space routinely for more than 50 years. I don't see zero -g as being a factor, and nothing has been said about operating a system like this in a vacuum.<br /><br />Equally a reactor on the NTP scale has not been operated in Space, that we know of, so the data for it is equally an estimation. I really wonder if you could get 200kw out of a 50,000 pound reactor, considering the cooling needs, containment requirements and the mass of nuclear fuels. <br /><br /> <div class="Discussion_UserSignature"> </div>