Or at least just preserve the orbit, and add on the pieces to the ISS instead. Launch costs being so high it seems almost criminal to just destroy such a costly investment. Sure, the parts of Mir may not be exactly right for the ISS, but at least you could keep them as unpressurized storage compartments. That's got to be cheaper than re-launching equivalent hardware from Earth.
Actually it would be much more expensive, not cheaper, because the planes of Mir's and the ISS' orbits are widely spaced - due to the fact that Russian mission controllers cannot handle both space stations passing overhead at too short an interval.
Sending it to a high enough orbit so that decay time becomes more than a few years is outside of the Progress' capability, I think. So the Russians either had to preserve it in orbit (except that their Soyuz/Progress production rate is barely enough for that, and they'll need twice as many for the ISS alone) or send it down.
The duration of the EVA is measured from the time the spacewalkers switch their suits to battery power and become autonomous, to the time they start repressurizing the airlock.
In this case, it lasted almost nine hours; but the last two were spent inside the airlock, back on Shuttle power and oxygen. The point was they had to be ready, should help be required in moving the PMA-3 Shuttle docking port. As in turned out, there was a problem which took time to solve. Help from the spacewalkers was eventually not needed, but that's why they spent so much time standing by in the depressurized airlock.
You are right, GaAs and InP can be very fast, but they are harder to fabricate: smaller wafers (hence fewer chip fabrication rates), higher costs, and more generally a few decades of technology development to catch up compared to silicon.
And this is problematic not only for fast electronics but also for active optical components, especially semiconductor lasers and amplifiers; silicon is a poor emitter of light due to its indirect-gap structure (in an E-k diagram, the bottom of the conduction band is not directly above the top of the valence band), so we have to use GaAs or even more expensive InP, especially for lasers in the 1.55micron wavelength range, i.e. the choice wavelength for long-range transmission over fiber optic...
(And, as with electronics, some researchers are trying to push the limits of silicon: there have been recent results with Si quantum-dot structures which were able to lase. But wouldn't it be easier in the long run to push GaAs technology?)
Of course you can't forward a mail without permission from the author! That's what copyright is about! An electronic mail, just as any piece of writing, is subject to copyright. If I send you one, under copyright laws, you may no more give away copies without my consent than if I had given you my latest manuscript. OTOH, you can use a reasonable portion of my text to quote me, or even make a parody, under fair use. This is ages old. Why is everybody acting outraged?
The only problem I would see would be the degree of required consent. What about messages on public forums, for instance? IANA(A)L but I'd say that the author of a news article implicitly agrees that his article will be copied and distributed on news servers all over the world; for a message on a WWW-forum it could be more troublesome but one could expect it to be replicated on caches. Only there could there be abusive restrictions due to a too-stringent interpretation of copyright.
Unless you want to challenge current copyright laws themselves; and there is reason to IMO, but that's another story.
You definitely have it backwards. Anything you write is copyrighted by default; if, say, there wasn't a copy of the GPL in the tarball, you would probably still be able to compile/run/modify it, but certainly not give away copies.
When you get up to 10 Ghz, the distance is only 1 cm- and aren't your typical Pentiums and Athlons bigger than that?
Pipelining takes care of that; even if the information cannot physically cross the chip end-to-end within one clock cycle, what counts is the time required to cross one set of logic gates (one "stage" of the pipeline). Even though one elementary operation takes more than one clock cycle to complete, you can "feed" the pipeline so that you actually get one result every clock cycle except at the beginning.
Furthermore, everybody messes up sometimes. Debian developers may well have broken something despite all the precautions they take before uploading a new package to Debian-stable. And there is something strange currently going on with FreeBSD 4.2-STABLE according to someone on the mailing-list.
And no, I myself have seldom if ever had problems with Apt on Debian-stable.
So? Say there is a security advisory, you should upgrade package ftpd. You get the updated RPM from RedHat (or Mandrake or whoever) and try to install it. RPM complains because ftpd depends on new versions of such-and-such libraries. You fetch the updated RPMs. You install all of them.
Guess what, that's exactly what Apt does, except that it uses.debs instead of RPMs (not counting recent developments). You run the very same risk that a post-install script in one of the packages messes something up, except that you had to get all the dependencies yourself...
I've tried reinstalling/reconfiguring the affected packages to no end.
Have you tried getting older packages and installing them over the newer ones with dpkg? Did you look at/usr/doc/<package>/changelog.* and README*? Did you try extracting the pre- and post-install scripts from the.debs (which are really ar archives containing data.tar.gz and control.tar.gz, the latter containing all the packaging stuff)?
As for myself, I don't usually use Apt directly, but the Apt method in Dselect. People say it's counter-intuitive, which it is, and difficult to use, which I don't think it is - once you get the grip of <space>, <enter>, +, -, _, =, R, Q it gets quite easy. Before upgrading
a system I look at which packages are going to change; if they are critical, I try to choose a time where I know I am physically close to the machine and can undo the upgrade one way or the other.
If we used my distro of choice (Slackware), I'd have an intimate understanding of my system and
would know right where to look when I get an error. But with apt, most of the packages on the machine are black-boxes; I don't know much about them outside their package name and function.
I disagree. The packaging has a black-box look (and even then you can easily open.debs with standard tools on any UNIX system, unlike RPMs) but what matters is the files they contain. PAM configuration is still in/etc/pam.*. Use dpkg -L to see what files are there.
Mostly:) That's why you use ten inches. Half-thickness. So although a few mm would stop most, it wouldn't stop everything.
Yeah but it's exponential. Supposing that five millimeters let through one electron in 10, an inch (about five times that) lets through one in 10^(-5) and ten inches one in 10^(-50). So if you throw all of the electrons in the universe at your wall, maybe a few will pass through.
I admit it's more complicated than that, and as a few people pointed out there's also the problem of radioactivity occuring within the casing itself.
The more transistors you cram into a chip and the faster you ask electrons to go, the more power
you need, and the CPU gets hot.
Large relative position uncertainty like you described only applies at the sub-atomic level. An entire atom has a predictable position in space and time.
Depends. At what temperature are you making your experiment? In other words, how much energy do your atoms have?
Need practical proof? Who has not seen the single-atom logo etches IBM and other research departments have been showing over the last decade?
Heat and watch...
Or how about the nano-machines that are just a few atoms thick reported here on/. and other places.
Those have many atoms, they are at least on the micrometer scale and a single atom is about ten thousand times smaller.
OTOH, how about atom-beam interferometry? How could that be possible if atoms had predetermined positions?
But at a subatomic level, it's already dettermined which way the light will be polarised. It's like tossing a coin, you think it's random but at the atomic level it's predetermined which way it goes.
Not according to quantum physics, which states that particles are probabilistic even down to the subatomic level. What is deterministic is a system's wave function, which yields the probability of the system being in a given state at a given time.
Maybe you are referring to the "hidden variables"
interpretation, which is quite controversial and almost debunked (see this "Layman's guide to quantum physics").
This is the frequency band that mobile phones use (GSM 900) so couldn't there be problems with interference, and public hype along the lines of mobile phone radiation.
Actually most mobile phones operate in the 900MHz and 1800 or 1900MHz ranges, AFAIK.
I didn't think one atom was possible, at least for conventional stuff. I thought semiconductors worked because of a group of atoms (usually silicon or that ge thing I can't spell) with covalent bonding, where a gap appears for electrons to get through. So unless you put them in groups I'd have thought two atoms would be the minimum...
Germanium (Ge)? Gallium arsenide (GaAs)?
You are correct that you can't have a semiconductor with only one atom. Even several atoms can't make it because in fact the energy bands (between which the gap is) are made up of many discrete states, each of which has a given energy. There are about as many of these in a band as there are atoms in the crystal. So, to get real (quasi-)continuous bands on each side of the gap, you need to have a macroscopic number of atoms.
Now, first, I didn't say that this IBM thing worked the same way as a semiconductor; I really don't remember the details and may very well be mistaken.
Second, these single-atom or three-atomic-layer systems are never isolated, they are always on a whole chip of their own, and this is going to have an energy-band diagram.
Yeah, but the most probable thing always happens, doesn't it?
No, otherwise its probability would be 1. If you prepare a system that has a 10:1 probability to be in a given state (say, you send light and arrange for it to be polarized at about 70 wrt to an analyzing polarizer) and repeat many times the experiment of measuring whether it is in that state (send many photons and detect how many pass through the analyzing polarizer), you'll find it is one time out of ten on average (10% of the photons will get through).
We normally think of cosmic rays as something that causes bit rot (though in practice it's alpha particles).
I find that a bit strange, as I'd say that most alpha particles will be stopped by the CPU casing, even a thin plastic one. OTOH, beta particles should easily penetrate that, and as they are actually electrons or positrons (mostly the former), they could be perfect to play havoc with the operation of a chip.
So I wonder; I'd say beta particles are more likely to be a cause for "bit rot", but lead and uranium radioactivity is alpha, AFAIK.
You could just imagine, tiny processors with a ten inch lead (as in the purified non-radioactive stuff) case round them.
You're thinking gamma rays or neutrons here. Alpha and beta rays (respectively helium ions and free electrons or positrons) are mostly stopped by a few mm of the stuff.
They could easily make processors not get hot, but they make people buy huge cooling fans instead to make more money.
The more transistors you cram into a chip and the faster you ask electrons to go, the more power you need, and the CPU gets hot. You can compensate for that only by using a finer design and that's why later generations of the same chip are cooler.
They may have done one transistor (and actually I seem to remember that IBM had succeeded with a single-atom one), but for doing anything useful you have to pack several of them together... And the closer you squeeze them and the faster you ask the electrons to get between them, the more you are subject to the tunnel effect, that is, the less said electrons care about the paths you carefully etch for them.
Indeed, the more energy they have and the thinner the isolation between "wires", the easier it gets for them to "hop" over the latter. By then anything can happen, bits leaking from one memory cell to the next, calculation errors...
They may be on the right path, but the way to go is quite long.
Sure enough, that show was crap, Apollo was a success, NASA did send people to the moon.
But sometimes I think of Apollo as having done more harm than good for the space program, not in the sense of having been expensive and useless (which it wasn't IMO), but of having desensitized the public while not going far enough.
The point is, Apollo's goal never was to do good science, setting up an outpost and/or preparing to colonize the Moon; a lot remains to be done there. But now, in the eyes of the public, going to the Moon "has already been done", is expensive, etc.
So maybe we should tell them all it was a hoax, perhaps they'll be more supportive of new Moon landings?
As usual, it's far easier to blame a scapegoat than actually going after the really guilty people. All the best if that scapegoat is the Internet: Average Joe doesn't understand anything about it, he doesn't realize that it's equivalent to blaming the phone lines, or the mail...
You make some very interesting suggestions. However, they would not really help with a number of handicaps the Shuttle has:
It would still be a big, one-size-fits-all craft, which cannot specialize on different uses.
What makes the Shuttle expensive is the standing army of government workers necessary to maintain it. And it has to be man-rated, so we can't spare triple-checking.
It would still be a government-subsidized launcher, which wouldn't have the same profitability requirements as a company which might want to enter that market, possibly with some new ideas.
The price reductions wouldn't be enormous, and the Shuttle is currently one of the most expensive launchers. And there is a theory that this will not be sufficient for new space-related markets to appear; I don't have a reference handy, but I saw it appear in a fairly recent Space Access Society bulletin. According to them, you'd need a much more substantial price reduction to create new markets...
All this is about is Cheap Access To Space (CATS).
But do we really need new technologies to reach that goal, or could we settle for lower-cost, off-the-shelf technology?
The problem is that if you want to develop a new launcher, and you're neither NASA nor Boeing or Lockheed, you aren't really credible. What NASA wants is to fly the Space Shuttle and keep a monopoly on human spaceflight (at least in the US), and develop new space technology as long as it can't compete with the former before a decade or two. What the big aerospace corporations want is to sell their existing expendable lauchers and maybe develop bigger ones at taxpayer expense. It looks like none of these players want CATS.
Look at their projects aimed at reducing launch costs. The DoD/McDonnell-Douglas Delta Clipper demonstrated a reusable rocket-based vehicle capable of quick turnaround by 1994; NASA sat on the funding before taking over the project, modifying the vehicle until it crashed. A competition was held for a follow-on, the X-33, whose stated goal was building a prototype of cheaply reusable, quick-turnaround suborbital vehicle using off-the-shelf technology; of the three competitors, the winner (Lockheed Martin's) was the one who most depended on new technologies; the vehicle is now two years behind schedule, over budget, underpowered and obsolete, and quite a number of people wonder whether Lockheed didn't fail on purpose ("see, it can't be done, buy our Titans!")
Finally, while a number of small companies are trying to get business done on inexpensive lauchers, they can't find investors as they are competing with NASA, especially with the recent Space Launch Initiative (SLI), aimed at subsidizing new launchers' development - favoring, as everybody expects, those which can meet NASA's requirements (one-size-fits-all, man-rated, heavy payloads) over commercial businesses' (cheap launchers aimed at a single market).
Where does all this leave us? Space is expensive, thus the market remains small, controlled by few players who ensure new ideas won't fly before twenty years and not cost less than what we have now, much less what IMHO we could do now. Sad, isn't it?
Slashdot Mirror
Actually it would be much more expensive, not cheaper, because the planes of Mir's and the ISS' orbits are widely spaced - due to the fact that Russian mission controllers cannot handle both space stations passing overhead at too short an interval.
Sending it to a high enough orbit so that decay time becomes more than a few years is outside of the Progress' capability, I think. So the Russians either had to preserve it in orbit (except that their Soyuz/Progress production rate is barely enough for that, and they'll need twice as many for the ISS alone) or send it down.
krakatoa ~ % echo $0
zsh
krakatoa ~ % echo X{a,b,c,d}{1,2,3,4,5}
Xa1 Xa2 Xa3 Xa4 Xa5 Xb1 Xb2 Xb3 Xb4 Xb5 Xc1 Xc2 Xc3 Xc4 Xc5 Xd1 Xd2 Xd3 Xd4 Xd5
Actually, everything is planned for; see NASA's FAQs about extravehicular activity ("spacewalking") and extravehicular mobility units ("spacesuits").
In this case, it lasted almost nine hours; but the last two were spent inside the airlock, back on Shuttle power and oxygen. The point was they had to be ready, should help be required in moving the PMA-3 Shuttle docking port. As in turned out, there was a problem which took time to solve. Help from the spacewalkers was eventually not needed, but that's why they spent so much time standing by in the depressurized airlock.
See the Spaceflight Now story for details.
How much time before the RIAA starts putting the pressure on the ISP linking Sealand to the shore?
You are right, GaAs and InP can be very fast, but they are harder to fabricate: smaller wafers (hence fewer chip fabrication rates), higher costs, and more generally a few decades of technology development to catch up compared to silicon.
And this is problematic not only for fast electronics but also for active optical components, especially semiconductor lasers and amplifiers; silicon is a poor emitter of light due to its indirect-gap structure (in an E-k diagram, the bottom of the conduction band is not directly above the top of the valence band), so we have to use GaAs or even more expensive InP, especially for lasers in the 1.55micron wavelength range, i.e. the choice wavelength for long-range transmission over fiber optic...
(And, as with electronics, some researchers are trying to push the limits of silicon: there have been recent results with Si quantum-dot structures which were able to lase. But wouldn't it be easier in the long run to push GaAs technology?)
The only problem I would see would be the degree of required consent. What about messages on public forums, for instance? IANA(A)L but I'd say that the author of a news article implicitly agrees that his article will be copied and distributed on news servers all over the world; for a message on a WWW-forum it could be more troublesome but one could expect it to be replicated on caches. Only there could there be abusive restrictions due to a too-stringent interpretation of copyright.
Unless you want to challenge current copyright laws themselves; and there is reason to IMO, but that's another story.
You definitely have it backwards. Anything you write is copyrighted by default; if, say, there wasn't a copy of the GPL in the tarball, you would probably still be able to compile/run/modify it, but certainly not give away copies.
Pipelining takes care of that; even if the information cannot physically cross the chip end-to-end within one clock cycle, what counts is the time required to cross one set of logic gates (one "stage" of the pipeline). Even though one elementary operation takes more than one clock cycle to complete, you can "feed" the pipeline so that you actually get one result every clock cycle except at the beginning.
Furthermore, everybody messes up sometimes. Debian developers may well have broken something despite all the precautions they take before uploading a new package to Debian-stable. And there is something strange currently going on with FreeBSD 4.2-STABLE according to someone on the mailing-list.
And no, I myself have seldom if ever had problems with Apt on Debian-stable.
So? Say there is a security advisory, you should upgrade package ftpd. You get the updated RPM from RedHat (or Mandrake or whoever) and try to install it. RPM complains because ftpd depends on new versions of such-and-such libraries. You fetch the updated RPMs. You install all of them.
Guess what, that's exactly what Apt does, except that it uses .debs instead of RPMs (not counting recent developments). You run the very same risk that a post-install script in one of the packages messes something up, except that you had to get all the dependencies yourself...
Have you tried getting older packages and installing them over the newer ones with dpkg? Did you look at /usr/doc/<package>/changelog.* and README*? Did you try extracting the pre- and post-install scripts from the .debs (which are really ar archives containing data.tar.gz and control.tar.gz, the latter containing all the packaging stuff)?
As for myself, I don't usually use Apt directly, but the Apt method in Dselect. People say it's counter-intuitive, which it is, and difficult to use, which I don't think it is - once you get the grip of <space>, <enter>, +, -, _, =, R, Q it gets quite easy. Before upgrading a system I look at which packages are going to change; if they are critical, I try to choose a time where I know I am physically close to the machine and can undo the upgrade one way or the other.
I disagree. The packaging has a black-box look (and even then you can easily open .debs with standard tools on any UNIX system, unlike RPMs) but what matters is the files they contain. PAM configuration is still in /etc/pam.*. Use dpkg -L to see what files are there.
Yeah but it's exponential. Supposing that five millimeters let through one electron in 10, an inch (about five times that) lets through one in 10^(-5) and ten inches one in 10^(-50). So if you throw all of the electrons in the universe at your wall, maybe a few will pass through.
I admit it's more complicated than that, and as a few people pointed out there's also the problem of radioactivity occuring within the casing itself.
I know, I'm part of it. <g>
Depends. At what temperature are you making your experiment? In other words, how much energy do your atoms have?
Heat and watch...
Those have many atoms, they are at least on the micrometer scale and a single atom is about ten thousand times smaller.
OTOH, how about atom-beam interferometry? How could that be possible if atoms had predetermined positions?
Not according to quantum physics, which states that particles are probabilistic even down to the subatomic level. What is deterministic is a system's wave function, which yields the probability of the system being in a given state at a given time.
Maybe you are referring to the "hidden variables" interpretation, which is quite controversial and almost debunked (see this "Layman's guide to quantum physics").
Actually most mobile phones operate in the 900MHz and 1800 or 1900MHz ranges, AFAIK.
Germanium (Ge)? Gallium arsenide (GaAs)?
You are correct that you can't have a semiconductor with only one atom. Even several atoms can't make it because in fact the energy bands (between which the gap is) are made up of many discrete states, each of which has a given energy. There are about as many of these in a band as there are atoms in the crystal. So, to get real (quasi-)continuous bands on each side of the gap, you need to have a macroscopic number of atoms.
Now, first, I didn't say that this IBM thing worked the same way as a semiconductor; I really don't remember the details and may very well be mistaken.
Second, these single-atom or three-atomic-layer systems are never isolated, they are always on a whole chip of their own, and this is going to have an energy-band diagram.
No, otherwise its probability would be 1. If you prepare a system that has a 10:1 probability to be in a given state (say, you send light and arrange for it to be polarized at about 70 wrt to an analyzing polarizer) and repeat many times the experiment of measuring whether it is in that state (send many photons and detect how many pass through the analyzing polarizer), you'll find it is one time out of ten on average (10% of the photons will get through).
I find that a bit strange, as I'd say that most alpha particles will be stopped by the CPU casing, even a thin plastic one. OTOH, beta particles should easily penetrate that, and as they are actually electrons or positrons (mostly the former), they could be perfect to play havoc with the operation of a chip.
So I wonder; I'd say beta particles are more likely to be a cause for "bit rot", but lead and uranium radioactivity is alpha, AFAIK.
You're thinking gamma rays or neutrons here. Alpha and beta rays (respectively helium ions and free electrons or positrons) are mostly stopped by a few mm of the stuff.
The more transistors you cram into a chip and the faster you ask electrons to go, the more power you need, and the CPU gets hot. You can compensate for that only by using a finer design and that's why later generations of the same chip are cooler.
Indeed, the more energy they have and the thinner the isolation between "wires", the easier it gets for them to "hop" over the latter. By then anything can happen, bits leaking from one memory cell to the next, calculation errors...
They may be on the right path, but the way to go is quite long.
But sometimes I think of Apollo as having done more harm than good for the space program, not in the sense of having been expensive and useless (which it wasn't IMO), but of having desensitized the public while not going far enough.
The point is, Apollo's goal never was to do good science, setting up an outpost and/or preparing to colonize the Moon; a lot remains to be done there. But now, in the eyes of the public, going to the Moon "has already been done", is expensive, etc.
So maybe we should tell them all it was a hoax, perhaps they'll be more supportive of new Moon landings?
As usual, it's far easier to blame a scapegoat than actually going after the really guilty people. All the best if that scapegoat is the Internet: Average Joe doesn't understand anything about it, he doesn't realize that it's equivalent to blaming the phone lines, or the mail...
The problem is that if you want to develop a new launcher, and you're neither NASA nor Boeing or Lockheed, you aren't really credible. What NASA wants is to fly the Space Shuttle and keep a monopoly on human spaceflight (at least in the US), and develop new space technology as long as it can't compete with the former before a decade or two. What the big aerospace corporations want is to sell their existing expendable lauchers and maybe develop bigger ones at taxpayer expense. It looks like none of these players want CATS.
Look at their projects aimed at reducing launch costs. The DoD/McDonnell-Douglas Delta Clipper demonstrated a reusable rocket-based vehicle capable of quick turnaround by 1994; NASA sat on the funding before taking over the project, modifying the vehicle until it crashed. A competition was held for a follow-on, the X-33, whose stated goal was building a prototype of cheaply reusable, quick-turnaround suborbital vehicle using off-the-shelf technology; of the three competitors, the winner (Lockheed Martin's) was the one who most depended on new technologies; the vehicle is now two years behind schedule, over budget, underpowered and obsolete, and quite a number of people wonder whether Lockheed didn't fail on purpose ("see, it can't be done, buy our Titans!")
Finally, while a number of small companies are trying to get business done on inexpensive lauchers, they can't find investors as they are competing with NASA, especially with the recent Space Launch Initiative (SLI), aimed at subsidizing new launchers' development - favoring, as everybody expects, those which can meet NASA's requirements (one-size-fits-all, man-rated, heavy payloads) over commercial businesses' (cheap launchers aimed at a single market).
Where does all this leave us? Space is expensive, thus the market remains small, controlled by few players who ensure new ideas won't fly before twenty years and not cost less than what we have now, much less what IMHO we could do now. Sad, isn't it?