I read the first edition of this book - it was great, and completely changed the way I handled (and understood) perl regular expressions. It's tempting, after reading this book, to try to apply regex's to everything! Friedl had an example of a huge, horrible (but efficient) regex to parse mail headers in the first edition - my advice on that is, don't try that at home! Interspersing procedural logic with the regex's tends to make much cleaner and more readable code...
We got a chance to chat with Michael Laine of LiftPort at this year's National Space Society annual meeting just a couple of weeks ago. They're looking for small investors already - talk to them if you would like to be involved at all. They will also have a private venture funding round coming up for larger investors, but anybody with a few hundred dollars could get involved at this stage (I think the deadline is June 20).
The US government already has 24 hours to review every image taken by US-owned spacecraft and decide whether or not to make them available based on national security concerns; there's no need to completely shut the thing down.
We're going to need some bandwidth allocation to allow solar power satellites or other space-based power options to transmit power to the ground without interfering too much with ground-based communications - quoting Hoffert and Potter:
the microwave spectrum is a limited resource jealously guarded by commercial and nonprofit users alike. Allocation of the spectrum must be addressed promptly and effectively to avoid preemption of space power technology before it's born.
> The reason we have not gone back to the moon is that most people in the US are not interested in it.
I keep hearing that - where does that assessment come from? I don't believe it. First off, people ARE interested in space, or NASA wouldn't get the billions it does right now. Second, of those people who show any interest in space that I've talked with, I would say 90% think we should have a base on the Moon by now, and wonder why NASA hasn't done anything about it.
NASA REALLY has avoided the moon, like the plague, pretty much since Apollo 17 returned. Over $3 billion has been spent on Mars missions (half of which failed), but only $60 million very grudgingly spent on one mission to the Moon in the last 30 years. That factor of 50 can't be just a matter of congressional oversight. The Department of Defense sponsored the only other US lunar mission (Clementine) of the past 30 years - what's with that?
NASA makes its case to Congress; there's a negotiation process there via the White House that sets the agenda for space. NASA staff testify frequently at congressional hearings. If these people aren't getting out the message that we can do wonderful things with the Moon, what's going on here?
Maybe we need more public advocacy, maybe there's just some other element missing, I don't know.
The difference between the Moon and Mars is the difference between solar/chemical and nuclear energy. If our conquest of space is going to be with nuclear power, Mars may make more sense as a location for early settlement. But there's abundant solar power out there - we still have 1.3 Kardashev levels to go just in this solar system! And if it's with solar power, and solar-driven plants to produce chemical rocket fuel, the Moon has all the ingredients we need to get moving.
Hey, I'm with you on that. But NASA bureacracy has been very strangely averse to planning anything about the Moon, at least since the last Bush administration's "Space Exploration Initiative" - and who were the people who came up with that $500 billion price tag to kill it with? NASA has some of the best people working for it and the strongest advocates for our future in space; unfortunately the people who manage it (and less directly but perhaps more responsibly, Congress itself) seem to have no real vision or interest in actually realizing all that potential.
If NASA had a more clearly defined mission to foster space development and industrialization, for example, and could be held accountable to that mission, the bureacracy couldn't get away with their conspiracy with Congress to fund centers that have no real purpose.
space elevator would definitely be a good thing - I was able to hear a talk by Michael Laine of LiftPort last weekend and he's got a great plan. The problem there is one big unknown piece of technology in the carbon nanotube ribbons that have not yet been built to the specifications needed. That's fundamental R&D that could be, like fusion, perpetually 20 years away. I hope it isn't, but we need to be able to work around it if that's what happens.
No, actually, you don't have to wait for lower lift prices, though they improve the initial capital cost picture. But even with current prices, using lunar resources, Criswell's lunar power system pays for itself over less than a decade at 1 cent/kWh final sale prices.
The Space Studies Institute has plenty of studies and reports on the benefits we could receive from power from space - solar satellites, Lunar Solar Power, etc.. There is no basic technology mystery there (unlike, say, fusion), the hardest pieces are some development bits relating to large-scale construction in space and use of resources on the Moon. But there's no public political interest in this for some reason, and the NASA budget category for this has been basically zeroed out for years (I believe the total spent has been about $50 million, with only $2 million spent looking at lunar options).
Why aren't we at least spending more money on research in this area? So many billions are spent on nuclear power, but space-based solar power is the ONLY way we'll ever move beyond Kardashev leve 0.7!
I picked up The Return at our local store a few weeks ago; wasn't expecting much (and the narrative style with four separate first-person voices seemed a little strange) but I was quite pleasantly surprised. It's a good story, though tainted perhaps by the anti-Clinton anti-China tilt of 3-4 years ago when it was written. But it also is amazingly prescient (the shuttle crash will give you chills) and guardedly optimistic about our future in space.
Not exactly a Neil Stevenson book, but a very enjoyable read.
Go read "The High Frontier" and come back and say that "we would still be unable to achieve colonization". There's no need for any fundamental breakthroughs - the solar system has 10 billion times more energy than we could ever exploit on Earth (and a somewhat smaller ratio of material wealth). What's needed is the capitalization to get started off this planet, and the human resources off planet to get the location-specific R&D done that will make it increasingly economical and even profitable. But it's not going to happen with all of us stuck in a rut down here.
People like Rees better get used to the fact that we aren't going to get off this planet in significant numbers any time soon and that colonization of space is a pipe dream for now.
100 years ago even less was expected of human flight. These days the average American flies about twice a year. What is so terribly unreasonable about the same happening for space flight? There are no physical constraints to huge numbers of people leaving this planet - the energy required is really not that large (roughly equivalent to the chemical energy content of a block of lard of the same weight). Now to actually do it for that energy cost takes something like a space elevator - rockets require substantially more energy, but even then it's far from impossible, just more expensive.
People seem to think the problem with space development is technology, and yes there's lots of fun technical challenges involved. But the real problem is that humanity has lost the will to do radically new things in our physical world - or at least humanity as exemplified by the USA. We no longer are willing to take any risks; nobody wants to be blamed for failure. But if something doesn't succeed the first time, abandoning it is an act of capitulation to the world that really is not worthy of a human being. Let's go out there and start taking risks again.
One interesting article along these lines is in this month's Atlantic Monthly - of course if you've been paying attention to the X-prize news we should start seeing suborbital rocket flights later this year too. So things may be moving forward again for us "space escapists", finally:-)
Silica is the primary component of the Moon's surface (and Earth's too) - this technique could greatly reduce the cost to produce useful things (like oxygen as a fuel component and for life in space, and silicon for solar cells) out of bulk lunar material.
Large-scale space construction is coming, and will provide one of the major markets for lunar materials. Martin Rees has a new book out that is pretty clear on why we need to develop space resources. Here's another enabling technology - now let's go do it!
Good Software Dev. book from SAIC
on
Inside SAIC
·
· Score: 1
"Successful software development" by Scott E. Donaldso and Stanley G. Siegel is one of the ones I've been looking at lately - the authors work at SAIC, and after reading it a bit I looked up the company a few weeks ago - very interesting place, it sounds like.
The first 90+% was just the "rectenna" side of things (which was what the first comment asked) - overall system throughput would likely be at the 60% level or so. But that's not bad for a long distance power transmission system.
As far as published journal articles on this, here's a link to an HTML version of an article "BEAMED MICROWAVE POWER TRANSMISSION AND ITS APPLICATION TO SPACE" published in IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 40, NO. 6, JUNE 1992, which covers the efficiency question in some detail, and a lot of other information besides. Worth reading...
I've met Zubrin and read some of his stuff - he's certainly persuasive. But you have to question his assumptions, just like anybody else. Personally I'm happy if the government takes the lead on Mars and private enterprise takes the lead on the Moon - there's a role for both. Space exploration isn't cheap - on the other hand, building nuclear power plants isn't cheap, building railroads isn't cheap, building a communications networks isn't cheap, but all those things have been done, and in the US, primarily by private enterprise. The long lead time is much more an issue for Mars than the Moon; we'll see how enterprise gets around that problem in the next few years.
Zubrin's a great motivator for space efforts, but I can't agree with everything he says...
Efficiencies of over 60% have been shown in DC-DC transmission of power (look up microwave power beaming in google some time). Your "a" and "f" are the same issue, and the "rectenna" also adds "e" into the same process, so whatever loss there is in "rectennafying" it's one step. I've read 90+% is possible there; don't know if it's ever been done in practice. Your "g" is there no matter what you do with the power at the end, so that's a wash. "d" one hopes will be kept low - in any case, losses with traditional power lines are often 50% or more...
So that basically leaves "b", "c", and your final comment on the inverse square law as problems. The first two of these are a question of conversion efficiency which somewhat favors low frequencies. The inverse-square law problem is basically an antenna-focusing issue: obviously you want a high-gain antenna on the transmitting end, and a "rectenna" on the receiving end that is big enough to catch the main lobe of radiated power. Diffraction limits impose a minimum size on the two antennas; to keep those sizes down for a given transmission distance, you end up favoring high frequencies. The balance between antenna size and component efficiencies favors different configurations depending on total power, distance, etc, but end-to-end efficiencies of at least 60% have been proven, and 90+% is thought to be theoretically possible.
I believe the origin of this idea is Glaser's 1960's proposal for solar power satellites, which would beam power to earth via microwaves in the same manner. Not sure if Glaser used the term "rectenna", but O'Neill certainly did in "The High Frontier".
The Space Access Society has its annual meeting this weekend; this is the first one since the X prize was announced to be fully funded last October, and the race has definitely been heating up.
This year is also the 100th anniversary of the Wright brothers flight, and a lot of these companies see this year as a terribly symbolic time to actually make it all happen.
It's time:-) Space enterprise will be the next big growth area - and NASA won't have a whole lot to do with it. Think of the shuttle accident as just another piece of motivation these guys need - right now the US has no human spaceflight capability, until one of these companies succeeds, or the shuttle starts flying again. Which do you think will happen first?
NASA's a government bureaucracy - PROFIT is the last of their goals... Remember this proposal wasn't from free-enterprise America, but from (no longer Soviet-) Russia...
If you're wondering what's up with all these private space ventures lately, the Space Access Society conference is going on right now. This particular contender is for freight, not human travel (at least at this point), and orbital, not suborbital as in the X Prize competition, which has also been heating up the last few months, since they got the full $10 million in the bank last October.
Well, you're right Ballmer got it wrong - but in a sense what's happening with a file in use under UNIX is sort of what happens with a hard link (not a sym link), not that you see many these days. With a hard link you have two file names that point to the same file by creating two directory entries pointing to the same inode (a sym link just creates a directory entry pointing to another filename, rather than an inode). With the hard link, the file doesn't get deleted unless both directory entries are removed. What you're talking about is the addition of open files in processes to the list of indoes treated in this manner. So I'd say Ballmer wasn't really all that far off either...
(Sigh, another interesting story I miss until it's been overwhelmed with dumb comments - not to disparage yours here, it's a good question...)
The detection of water on the Moon so far has been pretty indirect - various kinds of radar and neutron or other remote analysis from orbit, plus some plausibility arguments based on the Moon's orientation and orbit. We are pretty confident about it, but on the other hand, direct beats indirect any day, which is the reason for this and a variety of other missions being planned.
More info on other missions (I just added this one to the list!) available from the Moon Society.
I've listened to Ellison speak twice, and both times he seemed to be (1) insufferably arrogant, and (2) woefully ignorant about modern technology, even while excoriating the audience (at least by implication) for our ignorance of some piece of cultural history that had great importance to him. Not good traits in an SF author. Plus I've read a few of his stories, and they don't do much for me. Forget Ellison.
Slashdot Mirror
I read the first edition of this book - it was great, and completely changed the way I handled (and understood) perl regular expressions. It's tempting, after reading this book, to try to apply regex's to everything! Friedl had an example of a huge, horrible (but efficient) regex to parse mail headers in the first edition - my advice on that is, don't try that at home! Interspersing procedural logic with the regex's tends to make much cleaner and more readable code...
We got a chance to chat with Michael Laine of LiftPort at this year's National Space Society annual meeting just a couple of weeks ago. They're looking for small investors already - talk to them if you would like to be involved at all. They will also have a private venture funding round coming up for larger investors, but anybody with a few hundred dollars could get involved at this stage (I think the deadline is June 20).
The US government already has 24 hours to review every image taken by US-owned spacecraft and decide whether or not to make them available based on national security concerns; there's no need to completely shut the thing down.
> The reason we have not gone back to the moon is that most people in the US are not interested in it.
I keep hearing that - where does that assessment come from? I don't believe it. First off, people ARE interested in space, or NASA wouldn't get the billions it does right now. Second, of those people who show any interest in space that I've talked with, I would say 90% think we should have a base on the Moon by now, and wonder why NASA hasn't done anything about it.
NASA REALLY has avoided the moon, like the plague, pretty much since Apollo 17 returned. Over $3 billion has been spent on Mars missions (half of which failed), but only $60 million very grudgingly spent on one mission to the Moon in the last 30 years. That factor of 50 can't be just a matter of congressional oversight. The Department of Defense sponsored the only other US lunar mission (Clementine) of the past 30 years - what's with that?
NASA makes its case to Congress; there's a negotiation process there via the White House that sets the agenda for space. NASA staff testify frequently at congressional hearings. If these people aren't getting out the message that we can do wonderful things with the Moon, what's going on here?
Maybe we need more public advocacy, maybe there's just some other element missing, I don't know.
The difference between the Moon and Mars is the difference between solar/chemical and nuclear energy. If our conquest of space is going to be with nuclear power, Mars may make more sense as a location for early settlement. But there's abundant solar power out there - we still have 1.3 Kardashev levels to go just in this solar system! And if it's with solar power, and solar-driven plants to produce chemical rocket fuel, the Moon has all the ingredients we need to get moving.
Hey, I'm with you on that. But NASA bureacracy has been very strangely averse to planning anything about the Moon, at least since the last Bush administration's "Space Exploration Initiative" - and who were the people who came up with that $500 billion price tag to kill it with? NASA has some of the best people working for it and the strongest advocates for our future in space; unfortunately the people who manage it (and less directly but perhaps more responsibly, Congress itself) seem to have no real vision or interest in actually realizing all that potential.
If NASA had a more clearly defined mission to foster space development and industrialization, for example, and could be held accountable to that mission, the bureacracy couldn't get away with their conspiracy with Congress to fund centers that have no real purpose.
Alright, as the submitter on this story I just have to respond that I actually did grow up in Newfoundland... :-)
space elevator would definitely be a good thing - I was able to hear a talk by Michael Laine of LiftPort last weekend and he's got a great plan. The problem there is one big unknown piece of technology in the carbon nanotube ribbons that have not yet been built to the specifications needed. That's fundamental R&D that could be, like fusion, perpetually 20 years away. I hope it isn't, but we need to be able to work around it if that's what happens.
No, actually, you don't have to wait for lower lift prices, though they improve the initial capital cost picture. But even with current prices, using lunar resources, Criswell's lunar power system pays for itself over less than a decade at 1 cent/kWh final sale prices.
The Space Studies Institute has plenty of studies and reports on the benefits we could receive from power from space - solar satellites, Lunar Solar Power, etc.. There is no basic technology mystery there (unlike, say, fusion), the hardest pieces are some development bits relating to large-scale construction in space and use of resources on the Moon. But there's no public political interest in this for some reason, and the NASA budget category for this has been basically zeroed out for years (I believe the total spent has been about $50 million, with only $2 million spent looking at lunar options).
Why aren't we at least spending more money on research in this area? So many billions are spent on nuclear power, but space-based solar power is the ONLY way we'll ever move beyond Kardashev leve 0.7!
I picked up The Return at our local store a few weeks ago; wasn't expecting much (and the narrative style with four separate first-person voices seemed a little strange) but I was quite pleasantly surprised. It's a good story, though tainted perhaps by the anti-Clinton anti-China tilt of 3-4 years ago when it was written. But it also is amazingly prescient (the shuttle crash will give you chills) and guardedly optimistic about our future in space.
Not exactly a Neil Stevenson book, but a very enjoyable read.
Go read "The High Frontier" and come back and say that "we would still be unable to achieve colonization". There's no need for any fundamental breakthroughs - the solar system has 10 billion times more energy than we could ever exploit on Earth (and a somewhat smaller ratio of material wealth). What's needed is the capitalization to get started off this planet, and the human resources off planet to get the location-specific R&D done that will make it increasingly economical and even profitable. But it's not going to happen with all of us stuck in a rut down here.
100 years ago even less was expected of human flight. These days the average American flies about twice a year. What is so terribly unreasonable about the same happening for space flight? There are no physical constraints to huge numbers of people leaving this planet - the energy required is really not that large (roughly equivalent to the chemical energy content of a block of lard of the same weight). Now to actually do it for that energy cost takes something like a space elevator - rockets require substantially more energy, but even then it's far from impossible, just more expensive.
People seem to think the problem with space development is technology, and yes there's lots of fun technical challenges involved. But the real problem is that humanity has lost the will to do radically new things in our physical world - or at least humanity as exemplified by the USA. We no longer are willing to take any risks; nobody wants to be blamed for failure. But if something doesn't succeed the first time, abandoning it is an act of capitulation to the world that really is not worthy of a human being. Let's go out there and start taking risks again.
One interesting article along these lines is in this month's Atlantic Monthly - of course if you've been paying attention to the X-prize news we should start seeing suborbital rocket flights later this year too. So things may be moving forward again for us "space escapists", finally
Silica is the primary component of the Moon's surface (and Earth's too) - this technique could greatly reduce the cost to produce useful things (like oxygen as a fuel component and for life in space, and silicon for solar cells) out of bulk lunar material.
Large-scale space construction is coming, and will provide one of the major markets for lunar materials. Martin Rees has a new book out that is pretty clear on why we need to develop space resources. Here's another enabling technology - now let's go do it!
By the way, anybody in the SF bay area this coming weekend should check out the International Space Development Conference in San Jose, where we'll be discussing a lot of these ideas, and more!
"Successful software development" by Scott E. Donaldso and Stanley G. Siegel is one of the ones I've been looking at lately - the authors work at SAIC, and after reading it a bit I looked up the company a few weeks ago - very interesting place, it sounds like.
Metric helps on this one:
10,240 km/hour = 2844 m/sec
accelerating to that speed in 6 seconds means
474 m/sec^2 or about 48 times the 9.8 m/sec^2 of Earth normal gravity.
The first 90+% was just the "rectenna" side of things (which was what the first comment asked) - overall system throughput would likely be at the 60% level or so. But that's not bad for a long distance power transmission system.
As far as published journal articles on this, here's a link to an HTML version of an article "BEAMED MICROWAVE POWER TRANSMISSION AND ITS APPLICATION TO SPACE" published in IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 40, NO. 6, JUNE 1992, which covers the efficiency question in some detail, and a lot of other information besides. Worth reading...
I've met Zubrin and read some of his stuff - he's certainly persuasive. But you have to question his assumptions, just like anybody else. Personally I'm happy if the government takes the lead on Mars and private enterprise takes the lead on the Moon - there's a role for both. Space exploration isn't cheap - on the other hand, building nuclear power plants isn't cheap, building railroads isn't cheap, building a communications networks isn't cheap, but all those things have been done, and in the US, primarily by private enterprise. The long lead time is much more an issue for Mars than the Moon; we'll see how enterprise gets around that problem in the next few years.
Zubrin's a great motivator for space efforts, but I can't agree with everything he says...
Efficiencies of over 60% have been shown in DC-DC transmission of power (look up microwave power beaming in google some time). Your "a" and "f" are the same issue, and the "rectenna" also adds "e" into the same process, so whatever loss there is in "rectennafying" it's one step. I've read 90+% is possible there; don't know if it's ever been done in practice. Your "g" is there no matter what you do with the power at the end, so that's a wash. "d" one hopes will be kept low - in any case, losses with traditional power lines are often 50% or more...
So that basically leaves "b", "c", and your final comment on the inverse square law as problems. The first two of these are a question of conversion efficiency which somewhat favors low frequencies. The inverse-square law problem is basically an antenna-focusing issue: obviously you want a high-gain antenna on the transmitting end, and a "rectenna" on the receiving end that is big enough to catch the main lobe of radiated power. Diffraction limits impose a minimum size on the two antennas; to keep those sizes down for a given transmission distance, you end up favoring high frequencies. The balance between antenna size and component efficiencies favors different configurations depending on total power, distance, etc, but end-to-end efficiencies of at least 60% have been proven, and 90+% is thought to be theoretically possible.
I believe the origin of this idea is Glaser's 1960's proposal for solar power satellites, which would beam power to earth via microwaves in the same manner. Not sure if Glaser used the term "rectenna", but O'Neill certainly did in "The High Frontier".
The Space Access Society has its annual meeting this weekend; this is the first one since the X prize was announced to be fully funded last October, and the race has definitely been heating up.
:-) Space enterprise will be the next big growth area - and NASA won't have a whole lot to do with it. Think of the shuttle accident as just another piece of motivation these guys need - right now the US has no human spaceflight capability, until one of these companies succeeds, or the shuttle starts flying again. Which do you think will happen first?
This year is also the 100th anniversary of the Wright brothers flight, and a lot of these companies see this year as a terribly symbolic time to actually make it all happen.
It's time
NASA's a government bureaucracy - PROFIT is the last of their goals... Remember this proposal wasn't from free-enterprise America, but from (no longer Soviet-) Russia...
If you're wondering what's up with all these private space ventures lately, the Space Access Society conference is going on right now. This particular contender is for freight, not human travel (at least at this point), and orbital, not suborbital as in the X Prize competition, which has also been heating up the last few months, since they got the full $10 million in the bank last October.
Well, you're right Ballmer got it wrong - but in a sense what's happening with a file in use under UNIX is sort of what happens with a hard link (not a sym link), not that you see many these days. With a hard link you have two file names that point to the same file by creating two directory entries pointing to the same inode (a sym link just creates a directory entry pointing to another filename, rather than an inode). With the hard link, the file doesn't get deleted unless both directory entries are removed. What you're talking about is the addition of open files in processes to the list of indoes treated in this manner. So I'd say Ballmer wasn't really all that far off either...
(Sigh, another interesting story I miss until it's been overwhelmed with dumb comments - not to disparage yours here, it's a good question...)
The detection of water on the Moon so far has been pretty indirect - various kinds of radar and neutron or other remote analysis from orbit, plus some plausibility arguments based on the Moon's orientation and orbit. We are pretty confident about it, but on the other hand, direct beats indirect any day, which is the reason for this and a variety of other missions being planned.
More info on other missions (I just added this one to the list!) available from the Moon Society.
I've listened to Ellison speak twice, and both times he seemed to be (1) insufferably arrogant, and (2) woefully ignorant about modern technology, even while excoriating the audience (at least by implication) for our ignorance of some piece of cultural history that had great importance to him. Not good traits in an SF author. Plus I've read a few of his stories, and they don't do much for me. Forget Ellison.