Okay, so I'm not a petrol engineer... but then when does that sort of thing stop any good slashdotter?
RP-1 is a highly refined kerosine fraction.
Jet-A / Jet-A1 is a slightly less refined kerosine fraction.
K-1 Kerosine is yet another kerosine fraction. In some places, they skip out on K-1 and just sell Jet-A1 as kerosine for simplicity's sake.
There are other jet fuels that take a "wider cut" and include some napatha and gasoline fractions.
If you want, you can run turbines on all kinds of crazy stuff, although with modern catalytic oil processing, that's far less useful than it used to be.
Diesel engines can be made to burn Jet-A or RP-1.
Either way... the hardware to pump jet fuel/kerosine/etc. sorts of fluids is pretty well understood and easy to get ahold of. Not so for hydrogen.
I would think that it's better to say that it clearly won't meet NASA specs, because given the way NASA has worked in the past, if you have hardware ready and they won't like it, the spec will be carefully constructed to exclude your existing hardware.:)
Oh, and many many capsules have been launched sans heatshield on the first flight. Saves the trouble of a recovery crew and not accidentally landing on somebody or something.
Of course, seeing the Dragon makes them doing the Falcon 9 instead of the Falcon 5 make much more sense...
The biggest benefit won't be any exact products or technologies they create.
Building a rocket engine isn't as much science as plumbing. Doing it on the cheap especially.
The biggest benefit is a cost point. Even if SpaceX fails long-term, if they can prove that it is possible to get the cost of launch way down, it becomes possible for other people to get funding to make a go at it.
Kerosene is not the most efficent, in terms of mass, but it is rather efficent in terms of density. It's rather much like jet fuel, so there's already hardware to deal with it.
Hydrogen is more efficent in terms of mass, but it's not very dense, so you need huge tanks to store it. Also, it's cold enough to give you nasty materials problems that you don't get with just LOX.
So usually it makes more sense to use kerosene + LOX on the first stage because you are going to need a lot of fuel and you are going to have to push it through the atmosphere and stuff. Then once you are above the atmosphere and have ejected the first stage, the rest of the stages work better with hydrogen as the fuel.
The way I see things, if I find out that the military has spent all of the NASP / X-33 / A-12 / etc. money and any other misc. cost overruns and HASN'T used them to find anything particularly interesting, I'm going to be quite ticked off.
I mean, it's pretty well known at this point that the reason why the DSRV went so far over budget was because the money went to feed a number of other underwater engineering tasks, like tapping Russian undersea cables.
Aerospace black projects are nay but a fun game. Crackpots get stuff to chew on but never enough information to actually jeapordize any applicable projects. If anything, the potential of the black project is overestimated, not underestimated, by them. Any applicable opponents (commies, religous whackos, dictators, etc) can't rely on knowing that we *do* have the black aircraft, but can't ignore the possibilities. And it is usually the sort of thing where it is better that people don't know for sure about it until it gets used.
Well, yes, but you also have to remember that not all of the reasons for the promises of the 50s being broken were actually technological limits.
I mean, sure, we'll probably never see nuclear aircraft or trains. But a lot of the predictions in the 50s were extrapolations from the present day technology, and bad ones at that.
We went from smokestacks-as-a-symbol-of-progress to the current crop of environmental scare tactics. People are not able to rationally deal with the cold equations of how to move forward... how many people are killed because of coal plants vs. how many people who are killed because of nuclear plants... if a potentially increased cancer rate is an acceptable consequence when the fall of civilization is the leading alternative... etc.
I mean, you might as well have said that computers suck compared to what they were predicted to do by now by all sorts of folks. Just because we misjudged difficulties doesn't mean that there's not benefit.
No, the real answer is to make sure that a simple case of shoddy workmanship won't bring down the reactor. And to build the reactors such that they can withstand 10 times what the worst conditions on record is. Remember, the nuclear plant in California has been through several earthquakes without problems. You waste a lot of power transmitting it from place to place.
The answer is not necessarily to have a single standardized reactor design. For one, we don't know which of the potential interesting designs will work best in practice until we start building them. But also, having a small diversity in design will help if one of the designs turns out to have a flaw of some sort.
Yes, but where would you get the "most abundant substance in the universe" considering that most of the terrestreal sources of it are either fossil fuels or water?
Encouraging other countries to send us their nuclear waste is a great way to reduce proliferation.
See, if you run a nuclear reactor rod through the normal power-generating fuel cycle, by the time you reprocess it, you will have plutonium that's so contaminated with Pu-240 that you cannot use it in nuclear warheads.
Remember, enrichment seperates U-235 from U-238. That's easy -- three atomic numbers apart. Seperating Pu-239 and Pu-240 is hard because that's one atomic nubmer apart.
If you want to get bomb grade plutonium out of a reactor, you need to have each rod in the reactor for only a month or two and then reprocess it, to reduce the percentage of Pu-240.
The problem is, our current model, which is that we don't reprocess fuel and try to get other countries to not reprocess fuel, hasn't worked out so well. Iran, North Korea, and plenty of other countries have their own reprocessing plants for their nuclear power program. We should have just offered to reprocess their rods, free of charge, all along.
No, I'm mostly thinking about co-generation. Picture a PBR to power auto plants or ships or things like that.... stuff that nuclear energy was always promised as being able to do, but never really doing.
You are laboring under the assumption that there are not applications that use gold, or other rare elements for that matter, that wouldn't become very attractive if it were cheaper.
Really, there's no mining needed. Asteroids can be assayed remotely just like anything else and you pick out the most useful asteroids and drop them in an orbit or desert of your choice where you are set up for mining. Sure, it may take 5-10 years to get it there, but there's no need for anything other than a reflector and a beacon there.
Well, that may not be the case. The level of gravity required for long-term survival and reproduction is very much an open question and we don't have any especially good ways to research less-than-normal gravity.
But the ISS element that was going to research that is looking less and less likely to be launched. So we really don't know.
No, humans just need to not be headed for certain death.
Remember, most of the colonists who left their home countries didn't expect to come back. It was assumed that some of them would die even. But it was assumed that some would go off, prosper, and maybe even come back with sacks of gold.
I suspect that if you sent people on a mostly-one-way-mission to the moon with a sufficently large set of starter equipment, you could support them with a progressively-dwindling set of supplies over time, and nobody would be particularly unhappy with it. Sure, you might need to send them replacement parts for the lathe that they were using to make spare parts for the smelting plant.... but then they build an extra set of lathes and mills and don't need replacement lathe parts anymore. About all that you'd need to send the moonbase towards the end is enough water and nitrogen to compensate for outgassing.... and maybe not even that, after a while.
And robots are all nice and good, but they are very much limited. Have we built self-replicating robots yet?
Well, it's also one of those cases where it would be far too useful if it actually does work, so a certain amount of long-shot bets are a good thing.
The trick is to make sure that you are funding people with a genuinely crazy idea that has a one-in-a-million chance of working, not scam artists with no chance of working.
So the question was, "why won't this be the repeat of every previous time, given that there was even a proposal to build an extra shuttle owned by a commercial company that NASA found ways to quash".
NASA has a way of bowing to pressure where they will say, "Oh, sure, we'll open it up to ____" and then making sure it won't happen behind the scenes.
For example, neither the Soyuz nor the Shuttle comply with the standards they've set for spacecraft-that-may-operate-near-the-ISS. They were grandfathered in.
iTunes releases are probably in the same set of rights as a record release, so no. If an artist wants to jump ship, they need to wait until their record contract is up. The backcatalog will still be locked up in the old label.
It could be an inflection point for music if the industry follows through on their threats, however. Consider that right now, Apple cannot be too actively antagonistic towards the industry. There's nothing preventing them from drawing from Apple's pile of cash (smaller than Microsoft's, but still respectable) and building the infrastructure to offer the marketing and leverage of a big record label for indie iTunes artists, except that Apple doesn't want to push the record industry away too much.
To stop yourself with rocket engines instead of the atmosphere requires so much propellant that you'd never get up to space in the first place.
To reenter at any shallower angle would result in you skipping off the atmosphere, which becomes pretty hard to plan for.
The shuttle already uses its geometry to generate lift to descend more slowly.
About the only thing you can do to make the thing easier is to have a less dense craft. Part of why SSTO sounds good is that reentry with huge tanks means you have a signifigantly decreased heating load, which means you don't need the tiles, etc.
Of course, SSTO doesn't sound good for other reasons, mostly percentage of weight of the craft that must be fuel. Space is hard.
The SR-71s weren't nicely preserved, so it wouldn't be very likely that anybody would be able to get them back operational again. Same problem as resurecting any other piece of antiquated equipment -- even though we've got the plans and we may even still have the hardware, spares aren't easy to find, and if you don't sit down and properly preserve parts, they'll rot away.
The last time they tried to launch something off of a SR-71, it didn't end so well. Supersonic seperation is harder than you'd think.
Ah, but I'm not talking about taking the SS1 and "scaling it up" to reach orbit. I'm talking about progressively larger orbital launch vehicles as a "side effect" of Virgin Galactic.
I have a vauge feeling that it's cheaper to get a tank full of kerosine than it is to get the equivelent energy's worth of a rubber hybrid rocket core. Even though SS2 doesn't go to orbit, at some point along the way, it's going to start to make a lot more sense for them to invest in a set of liquid-fueled rocket engines, assuming that somebody can make a reliable long-lasting set of engines.
The thing is, I don't think there's new technology required to get an inexpensive orbital vehicle, just applying existing technologies to a functioning business model. And maybe Scaled+Virgin won't be the ones to do it, but.....
Slashdot Mirror
Sure.
:)
But if blu-ray takes off in the market, how long do you think downsampling will remain turned off?
If this wasn't a publicity stunt, it would be removed from the spec.
Not having your rocket explode is even safer.
:)
Witness the lack of escape tower in a modern airliner.
Okay, so I'm not a petrol engineer... but then when does that sort of thing stop any good slashdotter?
RP-1 is a highly refined kerosine fraction.
Jet-A / Jet-A1 is a slightly less refined kerosine fraction.
K-1 Kerosine is yet another kerosine fraction. In some places, they skip out on K-1 and just sell Jet-A1 as kerosine for simplicity's sake.
There are other jet fuels that take a "wider cut" and include some napatha and gasoline fractions.
If you want, you can run turbines on all kinds of crazy stuff, although with modern catalytic oil processing, that's far less useful than it used to be.
Diesel engines can be made to burn Jet-A or RP-1.
Either way... the hardware to pump jet fuel/kerosine/etc. sorts of fluids is pretty well understood and easy to get ahold of. Not so for hydrogen.
I would think that it's better to say that it clearly won't meet NASA specs, because given the way NASA has worked in the past, if you have hardware ready and they won't like it, the spec will be carefully constructed to exclude your existing hardware. :)
Oh, and many many capsules have been launched sans heatshield on the first flight. Saves the trouble of a recovery crew and not accidentally landing on somebody or something.
Of course, seeing the Dragon makes them doing the Falcon 9 instead of the Falcon 5 make much more sense...
The biggest benefit won't be any exact products or technologies they create.
Building a rocket engine isn't as much science as plumbing. Doing it on the cheap especially.
The biggest benefit is a cost point. Even if SpaceX fails long-term, if they can prove that it is possible to get the cost of launch way down, it becomes possible for other people to get funding to make a go at it.
Kerosene is not the most efficent, in terms of mass, but it is rather efficent in terms of density. It's rather much like jet fuel, so there's already hardware to deal with it.
Hydrogen is more efficent in terms of mass, but it's not very dense, so you need huge tanks to store it. Also, it's cold enough to give you nasty materials problems that you don't get with just LOX.
So usually it makes more sense to use kerosene + LOX on the first stage because you are going to need a lot of fuel and you are going to have to push it through the atmosphere and stuff. Then once you are above the atmosphere and have ejected the first stage, the rest of the stages work better with hydrogen as the fuel.
Hrm.
The way I see things, if I find out that the military has spent all of the NASP / X-33 / A-12 / etc. money and any other misc. cost overruns and HASN'T used them to find anything particularly interesting, I'm going to be quite ticked off.
I mean, it's pretty well known at this point that the reason why the DSRV went so far over budget was because the money went to feed a number of other underwater engineering tasks, like tapping Russian undersea cables.
Aerospace black projects are nay but a fun game. Crackpots get stuff to chew on but never enough information to actually jeapordize any applicable projects. If anything, the potential of the black project is overestimated, not underestimated, by them. Any applicable opponents (commies, religous whackos, dictators, etc) can't rely on knowing that we *do* have the black aircraft, but can't ignore the possibilities. And it is usually the sort of thing where it is better that people don't know for sure about it until it gets used.
Well, yes, but you also have to remember that not all of the reasons for the promises of the 50s being broken were actually technological limits.
I mean, sure, we'll probably never see nuclear aircraft or trains. But a lot of the predictions in the 50s were extrapolations from the present day technology, and bad ones at that.
We went from smokestacks-as-a-symbol-of-progress to the current crop of environmental scare tactics. People are not able to rationally deal with the cold equations of how to move forward... how many people are killed because of coal plants vs. how many people who are killed because of nuclear plants... if a potentially increased cancer rate is an acceptable consequence when the fall of civilization is the leading alternative... etc.
I mean, you might as well have said that computers suck compared to what they were predicted to do by now by all sorts of folks. Just because we misjudged difficulties doesn't mean that there's not benefit.
No, the real answer is to make sure that a simple case of shoddy workmanship won't bring down the reactor. And to build the reactors such that they can withstand 10 times what the worst conditions on record is. Remember, the nuclear plant in California has been through several earthquakes without problems. You waste a lot of power transmitting it from place to place.
The answer is not necessarily to have a single standardized reactor design. For one, we don't know which of the potential interesting designs will work best in practice until we start building them. But also, having a small diversity in design will help if one of the designs turns out to have a flaw of some sort.
Yes, but where would you get the "most abundant substance in the universe" considering that most of the terrestreal sources of it are either fossil fuels or water?
:P
You might as well try burning smog.
Yes, but you should also compare the cost of a single Hubble servicing mission than building a hubble replacement and launching it on an Atlas V.
Not necessarily.
Encouraging other countries to send us their nuclear waste is a great way to reduce proliferation.
See, if you run a nuclear reactor rod through the normal power-generating fuel cycle, by the time you reprocess it, you will have plutonium that's so contaminated with Pu-240 that you cannot use it in nuclear warheads.
Remember, enrichment seperates U-235 from U-238. That's easy -- three atomic numbers apart. Seperating Pu-239 and Pu-240 is hard because that's one atomic nubmer apart.
If you want to get bomb grade plutonium out of a reactor, you need to have each rod in the reactor for only a month or two and then reprocess it, to reduce the percentage of Pu-240.
The problem is, our current model, which is that we don't reprocess fuel and try to get other countries to not reprocess fuel, hasn't worked out so well. Iran, North Korea, and plenty of other countries have their own reprocessing plants for their nuclear power program. We should have just offered to reprocess their rods, free of charge, all along.
No, I'm mostly thinking about co-generation. Picture a PBR to power auto plants or ships or things like that.... stuff that nuclear energy was always promised as being able to do, but never really doing.
You are laboring under the assumption that there are not applications that use gold, or other rare elements for that matter, that wouldn't become very attractive if it were cheaper.
Really, there's no mining needed. Asteroids can be assayed remotely just like anything else and you pick out the most useful asteroids and drop them in an orbit or desert of your choice where you are set up for mining. Sure, it may take 5-10 years to get it there, but there's no need for anything other than a reflector and a beacon there.
Well, that may not be the case. The level of gravity required for long-term survival and reproduction is very much an open question and we don't have any especially good ways to research less-than-normal gravity.
But the ISS element that was going to research that is looking less and less likely to be launched. So we really don't know.
No, PRB's have one big advantage....
They have better energy density than RTG's but the same degree of safety (i.e. as long as you don't crack the casing, it's safe)
But, yes, there's a ton of neat reactor designs that should make nuclear weapon production harder, increase safety, etc.
No, humans just need to not be headed for certain death.
Remember, most of the colonists who left their home countries didn't expect to come back. It was assumed that some of them would die even. But it was assumed that some would go off, prosper, and maybe even come back with sacks of gold.
I suspect that if you sent people on a mostly-one-way-mission to the moon with a sufficently large set of starter equipment, you could support them with a progressively-dwindling set of supplies over time, and nobody would be particularly unhappy with it. Sure, you might need to send them replacement parts for the lathe that they were using to make spare parts for the smelting plant.... but then they build an extra set of lathes and mills and don't need replacement lathe parts anymore. About all that you'd need to send the moonbase towards the end is enough water and nitrogen to compensate for outgassing.... and maybe not even that, after a while.
And robots are all nice and good, but they are very much limited. Have we built self-replicating robots yet?
Well, it's also one of those cases where it would be far too useful if it actually does work, so a certain amount of long-shot bets are a good thing.
The trick is to make sure that you are funding people with a genuinely crazy idea that has a one-in-a-million chance of working, not scam artists with no chance of working.
Oh yeah.
So the question was, "why won't this be the repeat of every previous time, given that there was even a proposal to build an extra shuttle owned by a commercial company that NASA found ways to quash".
...here's the big question...
NASA has a way of bowing to pressure where they will say, "Oh, sure, we'll open it up to ____" and then making sure it won't happen behind the scenes.
For example, neither the Soyuz nor the Shuttle comply with the standards they've set for spacecraft-that-may-operate-near-the-ISS. They were grandfathered in.
iTunes releases are probably in the same set of rights as a record release, so no. If an artist wants to jump ship, they need to wait until their record contract is up. The backcatalog will still be locked up in the old label.
It could be an inflection point for music if the industry follows through on their threats, however. Consider that right now, Apple cannot be too actively antagonistic towards the industry. There's nothing preventing them from drawing from Apple's pile of cash (smaller than Microsoft's, but still respectable) and building the infrastructure to offer the marketing and leverage of a big record label for indie iTunes artists, except that Apple doesn't want to push the record industry away too much.
Ah.
Microsoft has to lose their biggest market and nearly go out of business first.
Remember, people were mad and afraid of IBM because they had the market on various things, most notably mainframes, locked up.
When the dominance of Windows is over, then there's room for thinking happy thoughts about Microsoft.
To stop yourself with rocket engines instead of the atmosphere requires so much propellant that you'd never get up to space in the first place.
To reenter at any shallower angle would result in you skipping off the atmosphere, which becomes pretty hard to plan for.
The shuttle already uses its geometry to generate lift to descend more slowly.
About the only thing you can do to make the thing easier is to have a less dense craft. Part of why SSTO sounds good is that reentry with huge tanks means you have a signifigantly decreased heating load, which means you don't need the tiles, etc.
Of course, SSTO doesn't sound good for other reasons, mostly percentage of weight of the craft that must be fuel. Space is hard.
The SR-71s weren't nicely preserved, so it wouldn't be very likely that anybody would be able to get them back operational again. Same problem as resurecting any other piece of antiquated equipment -- even though we've got the plans and we may even still have the hardware, spares aren't easy to find, and if you don't sit down and properly preserve parts, they'll rot away.
The last time they tried to launch something off of a SR-71, it didn't end so well. Supersonic seperation is harder than you'd think.
Ah, but I'm not talking about taking the SS1 and "scaling it up" to reach orbit. I'm talking about progressively larger orbital launch vehicles as a "side effect" of Virgin Galactic.
I have a vauge feeling that it's cheaper to get a tank full of kerosine than it is to get the equivelent energy's worth of a rubber hybrid rocket core. Even though SS2 doesn't go to orbit, at some point along the way, it's going to start to make a lot more sense for them to invest in a set of liquid-fueled rocket engines, assuming that somebody can make a reliable long-lasting set of engines.
The thing is, I don't think there's new technology required to get an inexpensive orbital vehicle, just applying existing technologies to a functioning business model. And maybe Scaled+Virgin won't be the ones to do it, but.....