Ares IV post brought up a good question.<br /><br />What propellants can be used to store in space so a booster can sit in an orbit for months (possibly years) to be used when a crew is ready to use them.?(Thinking of Mars mission and beyond). <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>
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With or without refrig( just make it work).<br /><br />Things that come to mind are <br />Some kind of solid fuel or hybrid system.<br /><br />On the complex side how about storing water in a tank and use electrolysis to make hydrogen and oxygen when coming close to use? <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>
From what I've read, LOX isn't really all that difficult to be made space-storable for reasonably long periods. LOX is a soft-cryogen and much easier to handle boil-off for than LH. I saw an article talking only about passive measures (i.e. thick insulation and sun-reflecting foil) that would drop boil-off rates into hundredths of a percent per day. If you truly want ZBO, adding solar panels to power a cryocooler (and incidently block more sunlight from hitting the tank) would not be extremely painful.<br /><br />*If* you assume LOX to be a space storable oxidizer, then the list of space-storable propellants is fairly lengthy -- including any number of hydrocarbons.
like what, methane, ethane, propane and butane? <br /><br />Can you give examples? <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>
Maybe we could take advantage of where its going to be stored. Like the temperature.<br /><br />Wonder if there is a propellant that becomes a solid at temperatures that resemble a martian orbit. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>
Hydrocarbons+LOX. liquid methane, ethane, and ethanol<br />Methane seems to be especially hip<br /><br />XCOR: http://www.xcor.com/products/engines/5M15_LOX-Methane_rocket_engine.html<br /><br />korean C&Space :<br />http://www.candspace.com/resboard/view.jsp?id=8&page=1<br />
<font color="yellow">"like what, methane, ethane, propane and butane?"</font><br /><br />Any of those. Also kerosene -- which would have topped my personal list.
>methane is hip<<br /><br />lol,<br /><br />I remember my dad doing an experiment to make methane, using animal dung (source of bateria), plant matter (food), and water. He was able to capture methane over time with no mechanical systems. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>
So essentially what are you saying, that if you have good source of baked beans along in your lunar lander, that just accidentally ran out of fuel, just sit back and relax ?
Several tonnes of storable UDMH/N2O4 propellants are maintained on the International Space Station. Something like 7 tonnes of new propellants may need to be brought up each year. Over the 20 year lifetime of the station, more than 100 tonnes will probably be needed, which is a bit more than the amount that would be needed for a single lunar mission if the EDS used storable propellants.<br /><br />Progress and Soyuz spacecraft, which can stay on orbit for six months at a time, are also fueled with UDMH/N2O4.<br /><br />Space Shuttle OMS and Orion use similar MMH/N2O4. The Delta II upper stage uses Aerozine 50/N2O4. These systems provide a specific impulse in the 316-319 sec range.<br /><br />These are toxic propellants, so the biggest issue would be the risk of a launch failure on or near the ground. But this would not be a new risk. Each Titan 4 was loaded with 190 tonnes of the stuff at liftoff.<br /><br /> - Ed Kyle
The 'storability' of a propellant depends on how much heat the spacecraft receives, thus the farther from the sun, the better. Boiloff is also higher in low earth orbit where reflected heat from the earth also warms the spacecraft.<br /><br />Here's an interesting link on the subject:<br />http://www.permanent.com/t-mikesc.htm<br />Interestingly, it's possible to passively store LH2 in the neighborhood of the outer planets, while even hydrazine is difficult to store around mercury. <br /><br />Since LOX gets close to zero boiloff near earth, it's possible to get ZBO at mars.<br /><br />That link favors ammonia as an easy to store means of carting hydrogen around, it's more efficient than water, and unlike oxygen, nitrogen is not available via ISRU (in appreciable quantities) in the earth's neighborhood.
Back in the early '70's, as part of a study I did in my second go-around at college, I used methane collected off a municipal sewage processing plant that produced natural gas as a byproduct of its chemical process to fuel a laboratory methane/GO2 rocket motor. The natural gas was about 60 percent methane, with CO2 and traces of other combustables. The rocket was a 1 lbf motor. My study concluded that IF one could set up a biomass in a spacecraft, you could produce enough methane to power thrusters, etc., plus, if you could break down the CO2, and had H2 aboard you could create more methane, water, etc. As I'm an engineer, not a chemist, I left the how-to to others. The project had earth-bound practical applications, as you could heat 10,000 houses with the natural gas by-product, if you put all of the then-population of Denver, Colorado, on the anerobic digester type sewage treatment. They never have done it, but DO tap landfills for methane.<br /><br />When I was a kid, we had another kid who had a tendency to be a bit...uh, er, flatulant! We joked that if we stuck him in the tail end of a rocket ship, and fed him beans and Ex-Lax...well, you get the picture! Might have had a problem with a high rate of nozzle erosion, however!<br /><br />Ad Luna! Ad Ares! Ad Astra!
LOX/Methane needs only relatively simple cryo-storage and yields a better Isp (365-370 seconds) than virtually anything else but LOX/LH2. Also, enabling the technology enables ISRU for the classic "Mars Direct" or any similar mission architectures. <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!! LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>
<font color="yellow">The rocket was a 1 lbf motor. My study concluded that IF one could set up a biomass in a spacecraft, you could produce enough methane to power thrusters, etc. </font><br /><br />Two issues to keep in mind: energy balance & mass balance.<br /><br />Anerobic digestion of human (animal) waste to produce methane is a slow, non-weight efficient method to produce them in space. <br /><br />Second, if you only have CO2 and H2 you can produce ALL kinds of hydrocarbon propellant. The process is called the Fischer-Tropsch synthesis. Hitler's industrial Germany use this technology to build up a military-industrial empire, as well as South Africa use this technology to produce all the energy, jet & diesel fuels that country needed. I would think the technology can be transformed to spacce production. <div class="Discussion_UserSignature"> </div>
I have a new personal favorite in this category: Paraffin.<br /><br />I'm thinking in terms of lunar operations, particularly a surface-hopping vessel. So I'm talking about the primary fuel for a lunar surface exploration system. But it also would be a terrific substance to stockpile at any habitat: you could store thermal energy in it, and then "huddle around the vat of molten wax" during the long night. If you tap out the thermal energy, you can burn it with your oxygen stores.<br /><br />A strategically spaced network of propellant depots on the lunar surface could enable a fleet of hopper-powered vehicles - manned and/or robotic - to explore the entire surface, gathering samples, making science observations, scouting for mining, tourism and science sites.<br /><br />We know we can make LUNOX, right? We haven't done it, but is there any doubt that the projected tech can be made to work?<br /><br />Rather than wait for the polar ice to be developed into rocket fuel, we could deploy LUNOX (Oxygen made from the lunar soil) factories in the near term.<br /><br />A propellant depot with oxidizer but no fuel doesn't make much sense, so a supply of fuel would be built into each LUNOX factory. LUNOX (once liquified) will be easy to store on the lunar surface, as long as you can put it in the shade. So you build a tent over the LUNOX facility and the fuel containers would be under the same tent.<br /><br />Some of the arriving hoppers would resupply the fuel, most would simply take on propellant mass and thus extend their journey into the wilderness. Later depots would just store LOX and wax, not produce LUNOX.<br /><br />The LOX would be pumped into tanks, and the Paraffin would be poured into the swapped-out rocket motor casings, the hopper's new full casings would ready to go in advance.<br /><br />This is a completely reusable propulsion system with throttle capable hybrid engines. The oxidizer is produced in-situ and the fuel is distributed from a central source. <br />The specific <div class="Discussion_UserSignature"> </div>
If you don't need a high thrust level, ion engines can open the doors to materials that would be useless in conventional rockets. A solar panel or RTG system would be enough to keep your fuel liquid and provide power for the engines (which need electricity). <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>
I've been saying, on this forum that water is the best means of transporting and storing propellant. It can be contained in minimal containers, freezing doesn't hurt it and with the abundant Solar power available it can be turned into Hydrogen and Oxygen as needed. <div class="Discussion_UserSignature"> </div>
I've only done some quick checking so far, no calcs yet.<br /><br />It can get up to ~500degC in temperature and still be a safe liquid in a closed container. The boiling point is ~200C higher, my reference wasn't clear but it would seem one would not want to operate in that realm anyway.<br /><br />The heat capacity is not great for heat storage as a liquid. I haven't checked the latent heat of melting, that would give you the additional energy you could extract as it solidifies at a constant temperature.<br /><br />I would expect once solidified, it wouldn't much care how cold it got. Just standard dimensional contraction, as long as it is highly purified.<br /><br />It seems unique in terms of ability to serve as a safe storage medium for thermal energy while also containing enough chemical energy to be a rocket fuel. <br /><br />Scott is likely not happy with this suggestion. 
The thing is, a barrel of water does not contain significant chemical energy but a barrel of wax does. <div class="Discussion_UserSignature"> </div>
The thing is, a barrel of water does not contain significant chemical energy but a barrel of wax does. <div class="Discussion_UserSignature"> </div>Although not as common as N2O4/UDMH, Hydrogen Peroxide/Kerosene is another storable propellant combo. While the Isp is lower than N2O4/UDMH, H2O2/Kerosene is non-toxic and therefore easier to handle. H2O2/Kerosene was used on the now defunct Beal BA-2 launch vehicle.<br /><br />Hydrogen peroxide can also be used as a monopropellant. If H2O2 comes in contact with silver, it decomposes into H2O and O2, and produces high-pressure steam in the process. While the Isp is crappy, it is hypergolic and therefore doesn't need any sort of heat source to ignite, making it usefull as a propellant for spacecraft thrusters.<br /><br />Brian Walker, aka Rocketguy ( www.rocketguy.com ), was going to build a homemade rocket propelled by a Hydrogen Peroxide monopropellant engine and ride it to about 50 miles. His web site hasn't been updated in several years, so it might be safe to assume that the project might be defunct by now. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>
Scott is likely not happy with this suggestion. <br /><br />Not at all. When you compare the ISP and handling considerations. I would question paraffin that had undergone a lot of temperature extremes. A solid motor needs a pretty stable propellant shape and grain or it is hard to predict the burn quality. <br /><br />In an everyday environment it would also be pretty hard to prepare motors for specific events. With H2 and LOX you simply calculate the needed burn time and start it up and turn it up, with a solid you tailor the burn time by varying the propellant load. True a Hybrid design, paraffin and LOX for example could be flexible in burn time, but you would still have to reload the motor with paraffin for different events.<br /><br />I still think water makes the best choice hands down, it can be used in an number of specific thrusters and motors . The motors can be started and stopped as needed and can be repeatedly started with little or no maintenance requirements. Water can also be transported and handled with little or no safety concerns and is storable in a minimal container, a condom could contain chunk of ice easily.<br /><br />Add the fact H2/LOX offers the highest ISP of any chemical propellant and that barrel of wax would also need a barrel of Oxygen to burn it seems pretty simple to me. <div class="Discussion_UserSignature"> </div>
<br /><br />Not at all. When you compare the ISP and handling considerations. I would question paraffin that had undergone a lot of temperature extremes. A solid motor needs a pretty stable propellant shape and grain or it is hard to predict the burn quality. <br /><br />In an everyday environment it would also be pretty hard to prepare motors for specific events. With H2 and LOX you simply calculate the needed burn time and start it up and turn it up, with a solid you tailor the burn time by varying the propellant load. True a Hybrid design, paraffin and LOX for example could be flexible in burn time, but you would still have to reload the motor with paraffin for different events.<br /><br />I still think water makes the best choice hands down, it can be used in an number of specific thrusters and motors . The motors can be started and stopped as needed and can be repeatedly started with little or no maintenance requirements. Water can also be transported and handled with little or no safety concerns and is storable in a minimal container, a condom could contain chunk of ice easily.<br /><br />Add the fact H2/LOX offers the highest ISP of any chemical propellant and that barrel of wax would also need a barrel of Oxygen to burn it seems pretty simple to me. <div class="Discussion_UserSignature"> </div>Hey, Spacester, speaking of LUNOX, this website: http://www.space-rockets.com/moon1.html has the interesting idea of using a LUNOX/Aluminum monopropellant. The idea calls for taking liquid oxygen and adding in aluminum powder to form a slurry. I imagine the Isp would be somewhere around the upper 200s/lower 300s which is not alot, but would be enough for a lunar surface to LLO shuttle. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>
"H2O2/Kerosene was used on the now defunct Beal BA-2 launch vehicle. "<br /><br />Not to mention by this funky beauty:<br /><br />http://en.wikipedia.org/wiki/Black_Arrow<br />http://members.aol.com/nicholashl/ukspace/blackarrow/blackarrow.htm<br /><br />Black Arrow performed the United Kingdom's first, and only, satellite launch.<br /><br /> - Ed Kyle
<blockquote><font class="small">In reply to:</font><hr /><p> Black Arrow performed the United Kingdom's first, and only, satellite launch. <p><hr /></p></p></blockquote><br /><br />Don't remind me! ...it's been downhill ever since (with the occasional, uplifting hump, like Bealge-2).<br />
<font color="yellow">"...(with the occasional, uplifting hump, like Bealge-2). "</font><br /><br />Are you saying that Beagle-2 was uplifting? I guess that could be read as 'very briefly uplifting' (i.e. 'like a hump'). <img src="/images/icons/smile.gif" />
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