My house is brick on the outside, and making brick involves heating it to where it starts to melt.
Morbo Voice: "BRICK DOES NOT WORK THAT WAY!"
Sintering does not involve melting. Sintering is where particles join by diffusion. It occurs at significantly below the melting points of the individual particles. For example, modern bricks are made at much hotter temperatures than ancient bricks, usually in the ballpark of 1000C. But the melting point of silica (largest constituent) is 1713C, while aluminum oxide (second largest constituent) melts at 2072C, iron oxide (third most) at ~1550C, and calcium oxide (fourth most) at 2613C.
Secondly, you use a giant furnace to make small bricks. So is your proposal to make a vastly larger space station in order to make a small one?
Third, while not all asteroids are fully sintered (aka, "rubble piles"), many are already that way. So what exactly is the point of what you're proposing?
The heating cycle for bricks takes longer than a day
Depends on the product. Low moisture bricks can take as little as 10 hours. And that's for the entire bake, which doesn't need to be done at once; there's multiple steps in the baking of a brick (base drying, dehydration, oxidation, and sintering)
And seriously, are we going to pretend that heat storage isn't a real thing, is that the plan?
You're not talking about glass if you're talking about melting meteorites. You're talking about a high-iron basalt. Slowly cooled basalt is known as columnar basalt. It has gigantic planar faults in it. Not to mention the effects of volatiles. Or differentiation. Or the effects of uneven cooling (which is why lava tubes form). And on and on and on.
At surface level, half of your surface is insulative (the ground). Earth's surface also receives more sunlight than most asteroids.
It's a silly concept. Look at how big solar tower farms are to raise a building-sized receiver to only a couple hundred degrees, and remember that heat radiates away proportional to the fourth power.
It also is sheer ignorance of what molten rock is like. News flash for these people: molten rock is not a blob of glass on a stick. It's not some easily workable yet viscous substance. It's irregular, heaves and fractures heavily and deeply, fractionalizes, cools highly unevenly (with lava tubes and dikes active much longer than other elements), kicks off trapped volatiles in an explosive manner, and a ton of other things you don't want at all, let alone in a structural object. People who promote this concept should visit at least one lava field before they do so (I live in Iceland, so I'm surrounded by lava). Basically, picture the most nightmare surface you could design for a car to drive over.... and that's basically what basaltic lava cools to. And it's a veritable sieve. The country is full of streams that appear and disappear because the water flows almost as easily through the highly fractured ground as it does on the surface. Is it even worth mentioning that you have to get it a lot hotter than glass, too? Asteroids, with their high nickel iron content, would need to be even hotter.
Maybe when you're talking megastructures might this be realistic. Maybe. When you're talking about anything in the even remotely near future, it doesn't even resemble reality. I totally agree with your statement that it's not a "good way to get started" - to say the least.
I love how just recently he was insisting vehemently that he had no idea who the hacker was.;) Also turned on Snowden the other day, insisting that Snowden's criticism of Wikileaks's curation policy is a betrayal from soneone who "hasn't leaked anything in three years" to try to get a pardon from Obama.
The family of slain Democratic National Committee staffer Seth Rich has a message to the Wikileaks crowd: Stop with the conspiracy theories.
After Wikileaks founder Julian Assange implied Rich was the source of the recent Democratic National Convention leak — and offered $20,000 for info on Rich’s murder — the grieving family slammed him for trying to “politicize this horrible tragedy.”
“The family welcomes any and all information that could lead to the identification of the individuals responsible, and certainly welcomes contributions that could lead to new avenues of investigation,” Rich family spokesman Brad Bauman said in a statement to Business Insider Wednesday.
“That said, some are attempting to politicize this horrible tragedy, and in their attempts to do so, are actually causing more harm than good and impeding on the ability for law enforcement to properly do their job.”
He urged the public to “refrain from pushing unproven and harmful theories about Seth's murder.”
Rich, 27, was shot and killed while walking to his Washington, D.C. apartment last month, and his killing remains unsolved.
Assange suggested this week, without evidence, that Rich played a role in leaking emails that showed DNC officials disparaging the presidential campaign of Vermont Sen. Bernie Sanders. The leak led to resignations for several DNC leaders.
“Whistleblowers go to significant efforts to get us material and often very significant risks. As a 27 year-old, works for the DNC, was shot in the back, murdered just a few weeks ago for unknown reasons as he was walking down the street in Washington,” Assange told Dutch TV station Nieuwsuur.
“I’m suggesting that our sources take risks and they become concerned to see things occurring like that.”
Wikileaks then offered a $20,000 reward for information on Rich’s killer.
Assange is the only public figure to claim there is a link between the leak and Rich’s death — even though he said in July he had no idea who the hacker was.
A hacker named Guccifer 2.0 claimed responsibility, but the source of the breach has not been determined. Democratic presidential nominee Hillary Clinton blamed Russian hackers, and Republican nominee Donald Trump then asked those hackers to steal Clinton’s emails.
I could get you pretty pictures for vastly cheaper.;)
Seriously, though, while I think the exploration is great, the fact that NASA has morphed into the All-Mars Channel is kind of annoying for those of us who prefer other destinations in the solar system (for me, it's Venus and Titan with a little Enceladus, Europa and Io on the side)
Even less than that. NASA doesn't use the CPI, they use the NNSI (Nasa New Start Inflation index). NNSI has a higher inflation rate than the CPI. Namely because while consumer goods have generally gone from things hand-produced and with domestic labour to things mass-produced with cheap overseas labour, NASA still predominantly builds low volumes by hand with highly trained domestic labour.
Heavy lift is a nice capability... if you can afford it.
1) It's always a lot easier to integrate components on the ground rather than in space 2) You can fly with much larger fairings, which means much larger components (SLS's fairing is roughly twice as big on each axis as Falcon Heavy's) 3) In theory, going big yields per-kilogram cost savings.
Unfortunately, SLS is just inappropriate in all regards here. The amount of overhead it inherits ensures that it will never be cheap, even by a per-kilogram standard, despite its size. And there's just not enough money to launch it frequently even if it was.
There's nothing inherently wrong with making heavy lift rockets. If you have the budget, and you have a lean development avenue, then it's probably a wise choice. NASA has neither. It's bloated with bloat that it's not allowed to ditch, which I'm sure must be very frustrating for its administrators. But as for heavy-lift itself... even SpaceX plans on going in that direction, with the MCT.
If it were affordable. It's not, particularly at the sort of budget levels on hand. So only rarely going to be used. So it'll never have economies of scale or the refinements (including safety) that come with having a long launch record.
Everyone tries to design missions to use it, though, to try to get buy-in to their plans, knowing that due to pressure in congress they want to find excuses to use SLS as much as possible, even if financially the option doesn't make sense. Example: I was reading some of the followup work on HAVOC the other day - HAVOC being an evolutionary approach for manned missions to Venus that a couple people at Langley have been promoting. Now, when I read their initial proposal, I could tell that clearly their call for SLS to launch the airship was way overkill. The entire hull (including the envelope) is 6455kg (and they call for the transfer stages and aeroshell to be launched separately). Throw all of the other mass of the airship (not counting the separately launched return rocket), such as propulsion, helium tanks for inflation, etc, and it's still only 25772kg. Obviously you don't need SLS to launch a 26 tonne payload to LEO. They describe it instead as being volume limited due to the volume of the fabric. They have something in the ballpark of 15k m surface area. They don't give their fabric thicknesses, but the heaviest Venus balloon fabric I've ever seen proposed on any mission was VALOR's, which is somewhere around 120um thick (most are much thinner than VALOR's). Using 120um as a baseline, with a perfect packing ratio, 15k m would take up 1,8 cubic meters. Multiply it by whatever factor you want to account for imperfect packing - you'll never come anywhere close to the need of SLS's 1100 cubic meter fairing.
In their followup, they pretty much confirmed this. They did a (very) small scale folding experiment, using the fabric they were proposing, at the thickness they were proposing. It fit into their accordingly scaled-down SLS fairing. Now, clearly, if you're scaling down your fairing volume and vehicle, but you're not scaling down your fabric thickness, then you're going to end up with something that takes up vastly more volume. Yet it still fit. So clearly they don't need anywhere near all that space**
** - Caveat: I don't know if they don't understand how blimps work or what, but they have no accounting for ballonets nor catenary curtains in any documents they've released that I've come across, nor do they compensate for the former with superpressure or phase change fluids, or the latter with a rigid keel or frame. Obviously ballonets and catenary curtains also are a source of mass and volume. But again, nowhere even close to mandating SLS.
This is hardly the only case I've seen like this. It seems like it's popular to try to baseline SLS into missions to try to get support for those missions. Whether or not SLS is actually needed. They know that they can always remove the SLS requirement if/when the system gets cancelled.
As for Wikipedia: it links to an article (not a report) citing a GAO report from 2014 (the report I linked is from 2015) comparing per hour costs of a wide range of planes (not specifically F-16s as in the actual report I linked), a report which is criticized in the article linked as “comparing apples and oranges.” and "...GAO’s methods mean their estimates are inherently out of date. Questions were also raised about the GAO’s methodologies for analyzing fuel costs..." and "It will be very interesting to see if the GAO sticks to these conclusions when the report gets approved for release." And Wikipedia's source is the one you just decried just moments ago, Breaking Defense, so strange that you'd now go tell me to read it.
So, your argument is, the DoD is lying when it describes in its own internal documents how much the F-35 costs to operate. And your contrary, higher O&S figures are in what document, exactly?
1) I was comparing payload capacity, not number of pylons. One always has a choice as to whether to make use of external hard points or not, based on the mission - which is why I mentioned both total payload capacity and internal capacity.
2) RCS has everything to do with when you can radar lock onto your foe vs. when they can lock onto you. It's not about the range of the missile, it's about when they can get the missile to hit you. If they can detect and fire at you from ~100km away while you have to wait for a close range IR lock, you don't stand a chance.
Huh? The F-35 has nearly double the payload capacity of the Jas Gripen and about a quarter more than a Eurofighter. Internal payloads are similar, but with a far smaller RCS the F-35 can engage at a much greater distance than its rivals can engage it.
This is simply not correct. The F-35's operating cost is nearly as low per hour as the old, much less advanced F-16, which has had nearly half a century to refine. See the line item above for maintenance, $10k per flight hour? The F-22 by contrast takes $33k maintenance per flight hour. Just the maintenance line item alone for the F-22 costs more than all O&S costs for the F-35 combined.
Because you've been reading sources focused on bashing the F-35? Which might explain the seemingly "inexplicable" interest by other parties who don't read exclusively efforts to bash it?
Most sources put the F-35's stealth at worse than the F-22. According to one article, the USAF stated that the F-22's RCS is "is the equivalent, for a radar, to a metal marble. The less stealthy (and much cheaper) F-35, is equal to a metal golf ball. The F-35 stealthiness is a bit better than the B-2 bomber, which, in turn, was twice as good as that on the even older F-117."
It was hard to keep the F-22's stealth to that level, however. It's also a bigger plane, which makes it more vulnerable to low frequency radar. Either way, they're both incredibly low cross section.
Also, all of these financial comparisons completely miss the point, as if the US wasn't going with the F-35 program, they'd be going with a different program instead. It's not like the US is just going to say, "Meh, I think our fighters are good enough, even though all of our potential adversaries keep advancing theirs..." And they would have again sought to go big, since there's a lot of aircraft to replace, and the more they produce the smaller the unit cost.
Yes, the F-35 is estimated at $1,5 trillion. Total through 2070. Aka, $28B per year, versus the Pentagon's $580B budget. And not all go to the US, there are many international orders as well. Procurement is only a fifth of that $1,5 trillion, or under $6B per year.
Again, yes, you could spend that money on, say, college education for people instead. If you're willing not only to let your adversaries out-tech your airforce, but also to scrap the current airplanes you're with that the F-35 is designed to replace, since that money also pays for ongoing operations costs that you'd have to pay for either way. You might be willing to scrap a large chunk of your airforce. Most Americans would not be, I'm sure.
Is it worth mentioning that many of the design decisions of the F-35 are designed to reduce operating costs, such as large production runs, a single engine design, etc - even though the unit cost is high? Again: production is only a fifth of total costs....
Slashdot Mirror
Morbo Voice: "BRICK DOES NOT WORK THAT WAY!"
Sintering does not involve melting. Sintering is where particles join by diffusion. It occurs at significantly below the melting points of the individual particles. For example, modern bricks are made at much hotter temperatures than ancient bricks, usually in the ballpark of 1000C. But the melting point of silica (largest constituent) is 1713C, while aluminum oxide (second largest constituent) melts at 2072C, iron oxide (third most) at ~1550C, and calcium oxide (fourth most) at 2613C.
Secondly, you use a giant furnace to make small bricks. So is your proposal to make a vastly larger space station in order to make a small one?
Third, while not all asteroids are fully sintered (aka, "rubble piles"), many are already that way. So what exactly is the point of what you're proposing?
Depends on the product. Low moisture bricks can take as little as 10 hours. And that's for the entire bake, which doesn't need to be done at once; there's multiple steps in the baking of a brick (base drying, dehydration, oxidation, and sintering)
And seriously, are we going to pretend that heat storage isn't a real thing, is that the plan?
You're not talking about glass if you're talking about melting meteorites. You're talking about a high-iron basalt. Slowly cooled basalt is known as columnar basalt. It has gigantic planar faults in it. Not to mention the effects of volatiles. Or differentiation. Or the effects of uneven cooling (which is why lava tubes form). And on and on and on.
At surface level, half of your surface is insulative (the ground). Earth's surface also receives more sunlight than most asteroids.
It's a silly concept. Look at how big solar tower farms are to raise a building-sized receiver to only a couple hundred degrees, and remember that heat radiates away proportional to the fourth power.
It also is sheer ignorance of what molten rock is like. News flash for these people: molten rock is not a blob of glass on a stick. It's not some easily workable yet viscous substance. It's irregular, heaves and fractures heavily and deeply, fractionalizes, cools highly unevenly (with lava tubes and dikes active much longer than other elements), kicks off trapped volatiles in an explosive manner, and a ton of other things you don't want at all, let alone in a structural object. People who promote this concept should visit at least one lava field before they do so (I live in Iceland, so I'm surrounded by lava). Basically, picture the most nightmare surface you could design for a car to drive over.... and that's basically what basaltic lava cools to. And it's a veritable sieve. The country is full of streams that appear and disappear because the water flows almost as easily through the highly fractured ground as it does on the surface. Is it even worth mentioning that you have to get it a lot hotter than glass, too? Asteroids, with their high nickel iron content, would need to be even hotter.
Maybe when you're talking megastructures might this be realistic. Maybe. When you're talking about anything in the even remotely near future, it doesn't even resemble reality. I totally agree with your statement that it's not a "good way to get started" - to say the least.
Duh! We do that all the time on Earth to make houses because it's such a trivial process. Isn't your home a lava gas home made with mirrors?
Let's not forget that previously Assange had been insisting that he didn't know who leaked the information to them.
I love how just recently he was insisting vehemently that he had no idea who the hacker was. ;) Also turned on Snowden the other day, insisting that Snowden's criticism of Wikileaks's curation policy is a betrayal from soneone who "hasn't leaked anything in three years" to try to get a pardon from Obama.
Seth Rich kin to Wikileaks: Stop the murder conspiracy theories
Tang is from China, and Chinese consumers are more into Tang than American consumers are.
The only real question is, when will China start sending Tang into space?
I did find one that contains the complete text of the Wikipedia article on pareidolia.
You really have to squint to see it, though.
But how will we ever manage to prove that the moon landings were faked if we never travel to the place on Mars where they were filmed?
I could get you pretty pictures for vastly cheaper. ;)
Seriously, though, while I think the exploration is great, the fact that NASA has morphed into the All-Mars Channel is kind of annoying for those of us who prefer other destinations in the solar system (for me, it's Venus and Titan with a little Enceladus, Europa and Io on the side)
Even less than that. NASA doesn't use the CPI, they use the NNSI (Nasa New Start Inflation index). NNSI has a higher inflation rate than the CPI. Namely because while consumer goods have generally gone from things hand-produced and with domestic labour to things mass-produced with cheap overseas labour, NASA still predominantly builds low volumes by hand with highly trained domestic labour.
Heavy lift is a nice capability... if you can afford it.
1) It's always a lot easier to integrate components on the ground rather than in space
2) You can fly with much larger fairings, which means much larger components (SLS's fairing is roughly twice as big on each axis as Falcon Heavy's)
3) In theory, going big yields per-kilogram cost savings.
Unfortunately, SLS is just inappropriate in all regards here. The amount of overhead it inherits ensures that it will never be cheap, even by a per-kilogram standard, despite its size. And there's just not enough money to launch it frequently even if it was.
There's nothing inherently wrong with making heavy lift rockets. If you have the budget, and you have a lean development avenue, then it's probably a wise choice. NASA has neither. It's bloated with bloat that it's not allowed to ditch, which I'm sure must be very frustrating for its administrators. But as for heavy-lift itself... even SpaceX plans on going in that direction, with the MCT.
If it were affordable. It's not, particularly at the sort of budget levels on hand. So only rarely going to be used. So it'll never have economies of scale or the refinements (including safety) that come with having a long launch record.
Everyone tries to design missions to use it, though, to try to get buy-in to their plans, knowing that due to pressure in congress they want to find excuses to use SLS as much as possible, even if financially the option doesn't make sense. Example: I was reading some of the followup work on HAVOC the other day - HAVOC being an evolutionary approach for manned missions to Venus that a couple people at Langley have been promoting. Now, when I read their initial proposal, I could tell that clearly their call for SLS to launch the airship was way overkill. The entire hull (including the envelope) is 6455kg (and they call for the transfer stages and aeroshell to be launched separately). Throw all of the other mass of the airship (not counting the separately launched return rocket), such as propulsion, helium tanks for inflation, etc, and it's still only 25772kg. Obviously you don't need SLS to launch a 26 tonne payload to LEO. They describe it instead as being volume limited due to the volume of the fabric. They have something in the ballpark of 15k m surface area. They don't give their fabric thicknesses, but the heaviest Venus balloon fabric I've ever seen proposed on any mission was VALOR's, which is somewhere around 120um thick (most are much thinner than VALOR's). Using 120um as a baseline, with a perfect packing ratio, 15k m would take up 1,8 cubic meters. Multiply it by whatever factor you want to account for imperfect packing - you'll never come anywhere close to the need of SLS's 1100 cubic meter fairing.
In their followup, they pretty much confirmed this. They did a (very) small scale folding experiment, using the fabric they were proposing, at the thickness they were proposing. It fit into their accordingly scaled-down SLS fairing. Now, clearly, if you're scaling down your fairing volume and vehicle, but you're not scaling down your fabric thickness, then you're going to end up with something that takes up vastly more volume. Yet it still fit. So clearly they don't need anywhere near all that space**
** - Caveat: I don't know if they don't understand how blimps work or what, but they have no accounting for ballonets nor catenary curtains in any documents they've released that I've come across, nor do they compensate for the former with superpressure or phase change fluids, or the latter with a rigid keel or frame. Obviously ballonets and catenary curtains also are a source of mass and volume. But again, nowhere even close to mandating SLS.
This is hardly the only case I've seen like this. It seems like it's popular to try to baseline SLS into missions to try to get support for those missions. Whether or not SLS is actually needed. They know that they can always remove the SLS requirement if/when the system gets cancelled.
As for Wikipedia: it links to an article (not a report) citing a GAO report from 2014 (the report I linked is from 2015) comparing per hour costs of a wide range of planes (not specifically F-16s as in the actual report I linked), a report which is criticized in the article linked as “comparing apples and oranges.” and "...GAO’s methods mean their estimates are inherently out of date. Questions were also raised about the GAO’s methodologies for analyzing fuel costs..." and "It will be very interesting to see if the GAO sticks to these conclusions when the report gets approved for release." And Wikipedia's source is the one you just decried just moments ago, Breaking Defense, so strange that you'd now go tell me to read it.
I'll repeat: your contrary, higher O&S figures are in what document, exactly?
So, your argument is, the DoD is lying when it describes in its own internal documents how much the F-35 costs to operate. And your contrary, higher O&S figures are in what document, exactly?
Did you even click the link? The document is from the DoD.
1) I was comparing payload capacity, not number of pylons. One always has a choice as to whether to make use of external hard points or not, based on the mission - which is why I mentioned both total payload capacity and internal capacity.
2) RCS has everything to do with when you can radar lock onto your foe vs. when they can lock onto you. It's not about the range of the missile, it's about when they can get the missile to hit you. If they can detect and fire at you from ~100km away while you have to wait for a close range IR lock, you don't stand a chance.
Huh? The F-35 has nearly double the payload capacity of the Jas Gripen and about a quarter more than a Eurofighter. Internal payloads are similar, but with a far smaller RCS the F-35 can engage at a much greater distance than its rivals can engage it.
This is simply not correct. The F-35's operating cost is nearly as low per hour as the old, much less advanced F-16, which has had nearly half a century to refine. See the line item above for maintenance, $10k per flight hour? The F-22 by contrast takes $33k maintenance per flight hour. Just the maintenance line item alone for the F-22 costs more than all O&S costs for the F-35 combined.
Because you've been reading sources focused on bashing the F-35? Which might explain the seemingly "inexplicable" interest by other parties who don't read exclusively efforts to bash it?
Most sources put the F-35's stealth at worse than the F-22. According to one article, the USAF stated that the F-22's RCS is "is the equivalent, for a radar, to a metal marble. The less stealthy (and much cheaper) F-35, is equal to a metal golf ball. The F-35 stealthiness is a bit better than the B-2 bomber, which, in turn, was twice as good as that on the even older F-117."
It was hard to keep the F-22's stealth to that level, however. It's also a bigger plane, which makes it more vulnerable to low frequency radar. Either way, they're both incredibly low cross section.
Yes, the F-35 absolutely can dogfight - for whatever that's worth these days.
Also, all of these financial comparisons completely miss the point, as if the US wasn't going with the F-35 program, they'd be going with a different program instead. It's not like the US is just going to say, "Meh, I think our fighters are good enough, even though all of our potential adversaries keep advancing theirs..." And they would have again sought to go big, since there's a lot of aircraft to replace, and the more they produce the smaller the unit cost.
Yes, the F-35 is estimated at $1,5 trillion. Total through 2070. Aka, $28B per year, versus the Pentagon's $580B budget. And not all go to the US, there are many international orders as well. Procurement is only a fifth of that $1,5 trillion, or under $6B per year.
Again, yes, you could spend that money on, say, college education for people instead. If you're willing not only to let your adversaries out-tech your airforce, but also to scrap the current airplanes you're with that the F-35 is designed to replace, since that money also pays for ongoing operations costs that you'd have to pay for either way. You might be willing to scrap a large chunk of your airforce. Most Americans would not be, I'm sure.
Is it worth mentioning that many of the design decisions of the F-35 are designed to reduce operating costs, such as large production runs, a single engine design, etc - even though the unit cost is high? Again: production is only a fifth of total costs....
Meh, learn to store all your money in Panama like we do over here in Iceland ;)