Funny how class warfare is such a one way street to the right.
Confiscatory taxes on the middle class that are used to shift wealth to the segments of the economy that can't be bothered to work (or to prepare themselves for work) are not class warfare, eh?
Warren Buffet wants wealthy people (like himself) to pay at least the same percentage of their income as the middle class do in taxes. I find it difficult to argue with that logic.
If he's concerned about the state of the U.S. Government's finances (and what fine upstanding pillar of the community would not be?) and can afford extra taxes, he need not wait for Congress to get around to levying them. He can most certainly write a check and send it to the Bureau of the Public Debt (www.treasurydirect.gov, hear they'll be taking Paypal soon!) Impress us by handing it over to your local congresslut during a press conference on national TV, with all the zeroes visible to everyone.
Or perhaps he's only interested in someone else paying extra.
Kick in some of your pocket change, Buffet, or shut up.
Fighting Intel is definitely fighting The Man. Back in the 90s I worked with a computer company that developed and marketed their own RISC architecture chip. Intel spent more in R&D annually than our entire company revenues and, shall we say, has a well-funded in-house legal department. Needless to say, their software now runs exclusively on Wintel.
Interestingly enough, Reno's buffer zone appears to actually be wider than required. *snip*
True. Remember that an aircraft going 400 mph will cover that 1000 feet in somewhat less than 2 seconds. To make an unlimited air race safe the setback would have to be so great that you might as well stay home and watch it on TV. Which would be a pity, since the visual is only a small part of the experience.
TRW's lunar module descent engine was quite a piece of engineering. Turns out that the ability to throttle down to 10% of rated thrust is rather difficult to achieve in a biprop engine. The eventual design made some serious compromises to gain the throttleability that generations have enjoyed in lunar landing simulators - it could not run stably at all in the 65%-95% range.
I can understand wanting to reinvent the wheel for the sake of the inventing, but this was a particularly tough nut to crack and one (to my knowledge) not yet duplicated elsewhere. Note that the throttling specified for the Purdue effort is 3:1, considerably less challenging than the 10:1 available to the Apollo astronauts during landing.
A better question is why mine the moon. If it's to create a lunar colony, all well and good, but such will never be self-sustaining. The two week sunlight cycle means that food cannot be grown without profligate use of energy. The almost complete lack of hydrogen, nitrogen, and carbon mean that most of our chemical processes are useless, and vast amounts of them will have to be imported expensively from Earth to enable human habitation. Man does not live by titanium, silicon, and oxygen alone, after all. (Admittedly, the far side would make an awesome location for a radio observatory, but that would not require human presence.)
If you're producing stuff for use off the moon, you have a severe handicap - the moon has enough gravity to make it expensive to loft goods back up into space. As a factory/depot for the exploration and exploitation of the rest of the solar system, Mars makes more sense, and there are probably asteroids whose composition would make them extremely valuable in that way as well.
The value to humankind of materials in space is that they are in space. A chunk of iron in orbit is worth much more because it can be used there without that 10 km/s penalty imposed by the Earth's gravity well, or the almost 3 km/s penalty required to loft something from the lunar surface to LEO.
Of course, all this assumes you have the will to want to build and use things in space to begin with.
Because humanity has a remarkable penchant for self-destructive behavior. We aren't going to change that. Ever. It's only a matter of time before some idiot(s) with sufficient weaponry and deficient intelligence, or simply continued unbridled population growth, make Earth a Bad Place to Live. That's why your forebears and mine left whatever dump they were living in, either to get away from nimrods, to find work that could support their families, or to get some breathing space. (Repeat preceding process until out of nice neighbors/food/jobs/room.)
Though an asteroid would work, too. Bring the karma, baby.
"Abundance" is, of course, a relative term. Average abundance of thorium in Earth's crust is around 7 ppm; most of it, however, is in much richer deposits, so that a handful of dirt from my backyard is essentially free of thorium. (I hope.)
The abundant levels on the Moon that you quote peak (not average) at around 13 ppm. Not trivial, but we won't be scooping it up in buckets and shoveling it into reactors either. The chemistry to extract and refine it using minerals and elements available on the Moon would have to be developed.
Perhaps I'm thinking of a different design, but as I understood the benefit of the ion engine, the bulk of the energy is coming in from the solar cells, the propellant only being used as the mass source.
You won't be using solar cells, at least not past Jupiter; the inverse square law means that you don't get much out of them past there.
So in other words, hydrogen is a clingy drama queen.
Actually hydrogen is kind of fabulously un-clingy, in the viscosity sense of the word.
Back to LH2 storage - NASA did a study quite a while ago about storage of liquid hydrogen in low earth orbit conditions. They determined that roughly 1% of the hydrogen would be lost (vented off to prevent tank from rupturing) every month, even with 20-layer Kapton insulation. That's without active refrigeration.
So hydrogen losses on a trip to Mars would not be prohibitive, though once down on Mars you'd want refrigeration since you're going to get some heat transfer from the atmosphere.
Lunar orbits are not stable over the long term, due to the mass concentrations ("mascons", chunks of higher density material embedded in the moon. Most are on the far side.) A libration point would be more appropriate, but would still require occasional orbital adjustments.
Slashdot Mirror
I don't pretend to know more than an astronomer, but doesn't the Sun catch a lot of things that would otherwise fly into Mercury ?
Perhaps more accurately, the Sun sucks a lot of things into Mercury. The planet is a vacuum bag on the Solar system's most impressive Hoover.
Funny how class warfare is such a one way street to the right.
Confiscatory taxes on the middle class that are used to shift wealth to the segments of the economy that can't be bothered to work (or to prepare themselves for work) are not class warfare, eh?
Warren Buffet wants wealthy people (like himself) to pay at least the same percentage of their income as the middle class do in taxes. I find it difficult to argue with that logic.
If he's concerned about the state of the U.S. Government's finances (and what fine upstanding pillar of the community would not be?) and can afford extra taxes, he need not wait for Congress to get around to levying them. He can most certainly write a check and send it to the Bureau of the Public Debt (www.treasurydirect.gov, hear they'll be taking Paypal soon!) Impress us by handing it over to your local congresslut during a press conference on national TV, with all the zeroes visible to everyone.
Or perhaps he's only interested in someone else paying extra.
Kick in some of your pocket change, Buffet, or shut up.
Fighting Intel is definitely fighting The Man. Back in the 90s I worked with a computer company that developed and marketed their own RISC architecture chip. Intel spent more in R&D annually than our entire company revenues and, shall we say, has a well-funded in-house legal department. Needless to say, their software now runs exclusively on Wintel.
Interestingly enough, Reno's buffer zone appears to actually be wider than required. *snip*
True. Remember that an aircraft going 400 mph will cover that 1000 feet in somewhat less than 2 seconds. To make an unlimited air race safe the setback would have to be so great that you might as well stay home and watch it on TV. Which would be a pity, since the visual is only a small part of the experience.
TRW's lunar module descent engine was quite a piece of engineering. Turns out that the ability to throttle down to 10% of rated thrust is rather difficult to achieve in a biprop engine. The eventual design made some serious compromises to gain the throttleability that generations have enjoyed in lunar landing simulators - it could not run stably at all in the 65%-95% range.
I can understand wanting to reinvent the wheel for the sake of the inventing, but this was a particularly tough nut to crack and one (to my knowledge) not yet duplicated elsewhere. Note that the throttling specified for the Purdue effort is 3:1, considerably less challenging than the 10:1 available to the Apollo astronauts during landing.
So why not just mine the moon?
A better question is why mine the moon. If it's to create a lunar colony, all well and good, but such will never be self-sustaining. The two week sunlight cycle means that food cannot be grown without profligate use of energy. The almost complete lack of hydrogen, nitrogen, and carbon mean that most of our chemical processes are useless, and vast amounts of them will have to be imported expensively from Earth to enable human habitation. Man does not live by titanium, silicon, and oxygen alone, after all. (Admittedly, the far side would make an awesome location for a radio observatory, but that would not require human presence.)
If you're producing stuff for use off the moon, you have a severe handicap - the moon has enough gravity to make it expensive to loft goods back up into space. As a factory/depot for the exploration and exploitation of the rest of the solar system, Mars makes more sense, and there are probably asteroids whose composition would make them extremely valuable in that way as well.
The value to humankind of materials in space is that they are in space. A chunk of iron in orbit is worth much more because it can be used there without that 10 km/s penalty imposed by the Earth's gravity well, or the almost 3 km/s penalty required to loft something from the lunar surface to LEO.
Of course, all this assumes you have the will to want to build and use things in space to begin with.
Because humanity has a remarkable penchant for self-destructive behavior. We aren't going to change that. Ever. It's only a matter of time before some idiot(s) with sufficient weaponry and deficient intelligence, or simply continued unbridled population growth, make Earth a Bad Place to Live. That's why your forebears and mine left whatever dump they were living in, either to get away from nimrods, to find work that could support their families, or to get some breathing space. (Repeat preceding process until out of nice neighbors/food/jobs/room.)
Though an asteroid would work, too. Bring the karma, baby.
There are also abundant levels of Thorium on the lunar near-side
"Abundance" is, of course, a relative term. Average abundance of thorium in Earth's crust is around 7 ppm; most of it, however, is in much richer deposits, so that a handful of dirt from my backyard is essentially free of thorium. (I hope.)
The abundant levels on the Moon that you quote peak (not average) at around 13 ppm. Not trivial, but we won't be scooping it up in buckets and shoveling it into reactors either. The chemistry to extract and refine it using minerals and elements available on the Moon would have to be developed.
Perhaps I'm thinking of a different design, but as I understood the benefit of the ion engine, the bulk of the energy is coming in from the solar cells, the propellant only being used as the mass source.
You won't be using solar cells, at least not past Jupiter; the inverse square law means that you don't get much out of them past there.
So in other words, hydrogen is a clingy drama queen.
Actually hydrogen is kind of fabulously un-clingy, in the viscosity sense of the word. Back to LH2 storage - NASA did a study quite a while ago about storage of liquid hydrogen in low earth orbit conditions. They determined that roughly 1% of the hydrogen would be lost (vented off to prevent tank from rupturing) every month, even with 20-layer Kapton insulation. That's without active refrigeration. So hydrogen losses on a trip to Mars would not be prohibitive, though once down on Mars you'd want refrigeration since you're going to get some heat transfer from the atmosphere.
So they can steal from their employers instead?
Lunar orbits are not stable over the long term, due to the mass concentrations ("mascons", chunks of higher density material embedded in the moon. Most are on the far side.) A libration point would be more appropriate, but would still require occasional orbital adjustments.