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How can that possibly be stable? Wouldn't the slightest deviation lead to the moon coming crashing down in either direction?

First google result about "Lagrange Points" :-p :
http://www.physics.montana.edu/faculty/cornish/lag range.html

The key here is that we're not talking about two static objects, but about two orbiting masses.

This leads to not one, but five Lagrange Points.
The one between the 2 masses (L1) is indeed unstable (like L2 and L3),
but L4 and L5 are both stable. That's where you'll find trojan objects.

And they are called "trojan" because of Jupiter's Trojan asteroids.

That's all folks.

Here's how a Lagrange point can be stable.

The Wikipedia article, a nice summary by mathematician John Baez, and another summary and a proof of L4/L5 stability (PDF) by astrophysicist Neil Cornish.

The Wikipedia article, a nice summary by mathematician John Baez, and another summary and a proof of L4/L5 stability (PDF) by astrophysicist Neil Cornish.

The Wikipedia article, a nice summary by mathematician John Baez, and another summary and a proof of L4/L5 stability (PDF) by astrophysicist Neil Cornish.

Same thing as normal moons.

Linky goodness.

Either language would be a fine choice for a first language.

I think Python has a few small advantages. First, there are many tutorials for Python that are aimed at new programmers. Examples include:

• How to Think Like a Computer Scientist
• Python 101
• Learning to Program
• Non-Programmers Tutorial For Python
• The Python tutorial that ships with Python itself (not really for absolute beginners, but this is where I learned Python)
• Plus many others, and I haven't even mentioned printed books.

The other advantange Python has over Ruby is the interactive Python interpreter. I can't explain how fantastic this is. With many other interpreted languages (Ruby, Perl), you really should write your program in a text editor and then run it through the interpreter. This is because the commands you type don't execute until you stop entering your program. The interpreter is not interactive. So every time you want to try something, you have make the change in your text editor and then run it through the interpreter.

Python's interpreter is much nicer to work with. You type in commands, and each command executes immediately. This is very useful when you want to experiment with the language, and is ideal for beginners. I don't know why Ruby's creator didn't include this feature.

Anyway, you'll be happy no matter which language you choose. They are both very nice. You might also consider learning PHP as a first languages. It's nice to be able to view the results of your work in a web browser, and PHP is probably the quickest way to do that. Another good choice for first language is Scheme. Check out the free online book Structure and Interpretation of Computer Programs (SICP). If you like video, there are also some video lectures available.

compensation for airplanes which fly over my house which is legal

Of course, we're constantly bombed with xrays from outer space too, though.

• 
  Believe it or not, I know of a computer that was built in the late 70's that could multiply numbers faster than today's fastest Pentiums can.

The OOo 2.0 beta definiately improves on native integration. Here's a shot of a recent beta version: http://www.cs.montana.edu/~ryanh/openoffice2.0beta .png The same old ugly icons, but those will probably be easier to fix. Also, the list of targeted features for OOo 2.0. http://marketing.openoffice.org/2.0/featureguide.h tml

Lawrence Lessig wrote about that in his book Free Culture (freely available online). He talks about it on Page 67 and shows his references on Page 317

Lawrence Lessig wrote about that in his book Free Culture (freely available online). He talks about it on Page 67 and shows his references on Page 317

I learned that denying people an inherently sharable commodity was hoarding and selfish. So when I brought something to school, I had to bring enough to share. Later when I learned about computers, I learned that it's unusual to "take" data; typically data is copied, not moved, from one computer to another. Still later, when I read more about the history of various media businesses, I learned that they got started doing what today they call "piracy" (even though, ironically, that term in the illicit copying sense was once used by authors to describe what publishers sometimes did).

I think all of these lessons and many others have made me increasingly appreciate free software over the years.

Uh...that's why you place the station and the reactors at Lagrange points, specifically L4 and L5. I'm not crazy enough to put one where it could come crashing back to Earth...

Actually Hubble is just at the upper edge of the orbit that the shuttle can obtain. It is not clear, at least to me yet, that given the safety changes requested to be made to the shuttle (adding new systems, back up capabilities and plans) if the shuttle could still achieve such orbits any longer. For example some of the fall back plans require visiting the ISS which I doubt they could have the fuel for given the large difference between the Hubble and ISS orbits.

I would love to see humans go up an do it since we know that works. In reality all that has changed in the perceptions of the risks to those humans...

Anyways I am also all for the use of robots. Not only will such a mission (hopefully) extend the life the Hubble but it will help advance robot technology in the field of maintenance and construction. This is the exact type of technology that will be needed to achieve a moon installation and future installations and orbiting stations.

If the technology can be developed it could reduce the cost of the deployment and upkeep of orbit based science equipment. In the long run it is a lot cheaper to send up robots then humans and can greatly expand the orbits achievable and even could allow maintenance at Lagrange points.

Have you checked out the Non-programmer's Tutorial for Python?
I'm currently having success teaching my wife how to program with it.

your statement that 'things with dimples' tend to fly farther is not really true. An aeroplane doesn't have many dimples does it? A golf ball flies further when it is rotating (in the right direction) since the air velocity at the top is higher than at the bottom (creating a pressure difference). The dimples serve to increase the roughness which increases the amount of air being acelerated/decelerated. It is exactly the same effect as a flettner rotor

DocBook XML and SGML require too much markup...

Another approach is simply to define your own markup language. Since your needs are simple, you probably don't need to validate your documents, so an informal description of a well-formed XML document is all the design you need to do. You'll also need to write transform software that creates HTML or whatever other deviverables you're trying to create. That's easy enough to do in XSLT.

One last suggestion: if you're serious about using markup that separates content and presentation (an attitude I heartily applaud) Slashdot is probably not the best place to get advice. You're inviting criticism and trolls from people who think that TeX, or even "Plain ASCII" is all anybody really needs. Try some of the XML forums, like XML doc

The story is repeated in Free Culture (page 107).

The book is distributed under a license that allows you to convert it and redistribute it. For example, here is a version of the book Free Culture that is html (some foobared characters and missing footnotes). It's not perfect, but feel free to fix the problems and reply to this thread. So get off your lazy bum and convert the darn thing to your favorite format.

Steven Weinberg, like so many scientists of a certain ilk, is just scared that funding for his favorite science projects will be cut. He's about the fourth one I've read recently who are ranting about how 'useless' manned space flight is. His vision is shortsighted and ignores the long term economic benefits, not to mention the incalculable social benefits. Too many pure-research oriented scientists are looking only at their own narrow interests. They're all wrong, wrong, wrong.

Wienberg's economic numbers are wrong. He ignores the data that have shown that the US economy experienced a long term return of over 20 to 1 on the manned space program of the 1960's. (I don't have a link to the data, sorry - it's been 10 years or so since I saw it.)

One might almost say that the American high tech industry was born in the manned space program. Tech invented or developed for NASA include silicone seal, originally developed to seal the windows in spacecraft; a wide variety of high tech metallurgy, ceramics and plastics; avionics, digital cameras, aeronautics, a huge acceleration in electronics, communications and integrated circuit technology, even areas such as systems management, risk assessment.

The manned space program gave a huge boost to engineering employment, thus encouraging a generation of Americans to get science and technical degrees, driving the tech revolution through the 1970's and beyond. Those people multiplied the pace of innovation with commercial applications and new tech. This literally changed America's view of itself from an industrial to a technological nation. Silicon Valley is in many ways a child of the manned space program!

Technologies like the hypersonic plane will have synergies with the Mars project, benefiting from the manned program budget and acting as an enabling technology. If the hypersonic plane succeeds, the potential savings for putting things in space may well pay for the entire Mars program. The projected reduction in launch cost, presently $22,000 per kg, will generate a huge increase in the number and variety of Near-Earth orbital projects, making a number of new scientific and commercial applications feasible at last, most of which nobody has thought of yet.

The technologies created will have a multiplier effect, just like in the 1960's and 1970's. For example, it may well create a real orbital vacation travel industry, which in turn will generate a stampede for commercial space projects, with the attendant operational cost reductions. Technologies for space travel will become more and more mature, greatly improving safety and reliability as well as cost. It will be ever cheaper and safer for humans to stay in space for longer terms.

Then there's the resources. Once you're out of Earth's gravity well, getting around is fairly cheap. Even beyond mining on the Moon or Mars, mining the asteroids could completely alter the economic equations on Earth. A single smallish nickel-iron asteroid contains more iron than has ever been mined on Earth. The rocky asteroids have other minerals - silicon, aluminum, etc. Once we Terrans have established a permanent presence in space, construction of spacecraft in space will become cheaper than on Earth. Space will become a net producer relative to Earth much sooner than we think.

Everything I've mentioned could be true within 50 years, possibly within 30 years. If the initiative goes forward, President Bush will be eventually be looked at as the "Queen Isabella" of space colonization, who had the vision to support Columbus and made Spain the largest economic power in Europe within 30 years. I'm looking forward to watching the next alignment of planets in 2036 from my hotel room orbiting at the Lunar L5 point.

L5 is on the dark side of the moon right?

Nope. L5 trails the minor body on its orbit by 60 degrees.

http://www.physics.montana.edu/faculty/cornish/lag range.html

<PICK type="nit">
There is no dark side of the moon. Only a far side. (That's why we have new moons -- the sun is shining on the part we can't see.)
</PICK>

Except Excel is notoriously unreliable for statistics, and MicroSoft seems to be uninterested in fixing the known (for years) problems with distributions, linear regression, etc.

this has an overview and citations.

If you need particular kinds of stats, a tweaked Rweb server might be one option - set it up to run "canned" analyses on user data. You'd have to have a web server available, obviously, plus enough knowledge of R/Splus to set up the analyses necessary.

I have something very much like this set up with a database interface to allow my collaborators to run canned analyses (or any, if they know the R needed) on the most current data.

Okay... having gotten way afield from where I meant to go... be very, very careful using Excel for any kind of stats!

<a href="http://www.physics.montana.edu/faculty/corni sh/lagrange.html">Here's how</a>

It may just be a symptom of my generation, but I really think the reason we need a moon base is obvious.

I take it as a given that we need to establish a self-sufficient human presence off of this planet; we are screwing this one up at a amazing rate, and so many things exist that can destroy the race in a relatively short period of time it's ridiculous; from Planet killer asteroids, to mutant Ebola, to a new cold war, to killing all the plankton which produce the majority of our oxygen... etc.

In order to have a self -sufficient human presence in space, raw materials are going to be necessary; it's stupid to boost all the construction materials out of the earth's gravity well, when we can just mine the moon; alternately, I could see towing a asteroid to a LaGrange point, but that's possibly beyond us currently.

Once we have the moon, we have it all; a electromagnetic catapult to put processed raw materials back into orbit or shoot them to the earth would easily pay off the cost of putting a base there. The only problem I can see would be water, if ice turns out to not exist at the poles as some think (I don't); the easy availability of selenium, and abundant Solar power, should make making our own water out of elemental H & O a snap.

And, the best argument; President-for-life Bush will be able to drop gigantic canisters of rock anywhere on the planet he wants to suppress dissidents terrorists! peace in our time!.

Which is why I'm encouraging my kids to either pursue mechanical engineering or aerospace tech; I want them OFF this planet as soon as its possible.

RTFA

For one thing, you have to include the centripetal forces exerted on the satellite as it's orbiting. The Lagrange points are places where the centripetal forces exactly cancel the gravitational forces.

The L4 and L5 points are stable. If the satellite drifts out of position then the gravitational and centripetal forces acting on it will nudge it back into position.

But the L1, L2 and L3 points are unstable. If the satellite drifts even slightly then the gravitational and centripetal forces will not be cancelled and they will actually pull it further out of position. Even a very small force, like that exerted by the solar wind, would push it out of position given enough time. So a station at L1 would always need some kind of propulsion system to keep it positioned correctly.

See this link for more info.

Not nearly as much as you think; possibly none at all. That's the whole reason to put one in the Lagrange points, well, half the reason anyway.

Grandparent is actually right here... L1, L2, and L3 are all unstable points (they're literally "points", so anything larger than 1 dimension is going to drift). L4 and L5 are stable points, since they're gravity wells - things will tend to stay there.

For example, the Earth-Sun L2 point requires station keeping corrections roughly every 23 days.

-T

If I'm reading his topographic-like chart (see this article) correctly, it would appear that the cheapest points to get to would be L1 and L2 (because of the gravity trough between the bodies). L4 and L5 are actually gravity peaks (not troughs) and it's the Coriolis effect of the body speeding and slowing that keeps bodies stable.

Until we invent some new form of propulsion that gets a bit more punch, a space platform needs a cheap transport route. Imagine having to truck all those extra-Earth goodies to those gravity peaks (although trucking from them would be a touch cheaper)...

In other words, like many religious folk, the Linux-loving crunchies in the open-source movement are a) convinced of their own righteousness, and b) sure the whole world, including judges, will agree.

They should wake up...

Linux will turn out not to be the savior everyone thinks. Customers will begin to realize that IBM...doesn't "give" you "free" Linux--unless you pay through the nose for hardware and services. Someone might notice that it's been 10 years since Linus Torvalds created Linux and there's still not a decent desktop version that an ordinary person can use. Someone also might notice that Red Hat's...sales aren't growing very much, and that the company only shows a profit when it fiddles the numbers around into an "adjusted" basis, not when it follows GAAP rules.

If you really know him, tell him to give me a holler. I'm available through the E-Mail listed here as well as the address I gave Forbes (along with my real name). He can do an easy search on the text since what I posted here is my Letter to the Editor verbatim.

woof.

if you can't open the file you can't photograph the file.
successfully photographing documents off a monitor has never been all that easy: Making 35 mm Slides by Photographing a Computer Screen. playing James Bond with your cheap, pocketable, digicam might not cut it.
of course if you want get all paranoid about it you'd better find a way to scan your incriminating photo-docs for stenographic clues that might come back to bite you later.

I would say these things become a concern at distances of 100 feet or more - 50 if you have bad luck or good ears.

Attenuation, or how much power goes into heating the wires instead of moving the speakers, is easier to calculate. Your speaker system will have a specified impedance (for home speakers, usually 8 ohms, sometimes 16 ohms) with a DC resistance very near this. Add that resistance to the resistance of your wire (look up the ohms per foot in a wire table) and divide the speaker's resistance by the total (for example, if you have 8 ohm speakers, and your wire resistance was 1.5 ohms, only 8/9.5 or 84% of your power would make it to the speakers).

Web sites offering legal information (DISCLAIMER: which is not the same as legal advice) disagree. This page claims: "It is always permissible to use a patented invention for research purposes," but this page denies the existence of such an exception to the patent monopoly.

Any lawyers in the audience?

Sometimes theyâ(TM)re just injected with dye: Painted fish, which is pretty cruel.

I wonder how a buyer could tell the difference?

âas more than 90 per cent have been sterilizedâ I guess having your organs glow is a bit of a downside here too. Must make the remaining 10% glow relatively brighter.

Sometimes itâ(TM)s best to go low-tech, like Gibson says. (I hope you know where â¦)

And Iâ(TM)m sure the dolphin with the SQUID would agree.

Not to shatter illusions too much, but believe it or not, Montana does have Internet access (afterall, I am posting right now, eh?). In fact, there is a growing Internet community with online technology companies right here in Bozeman including Right Now Technologies and my own company, Bridger Systems. With the influx of people into the western half of the state over the past ten years, we are getting more and more infrastructure. Though cable modems have not yet arrived in my town (I believe it exists in Missoula and Billings), we have DSL and wireless broadband access. Furthermore, there is a strong computer science department at Montana State University. Montana is not quite the isolated wilderness that people think it is.

Not to shatter illusions too much, but believe it or not, Montana does have Internet access (afterall, I am posting right now, eh?). In fact, there is a growing Internet community with online technology companies right here in Bozeman including Right Now Technologies and my own company, Bridger Systems. With the influx of people into the western half of the state over the past ten years, we are getting more and more infrastructure. Though cable modems have not yet arrived in my town (I believe it exists in Missoula and Billings), we have DSL and wireless broadband access. Furthermore, there is a strong computer science department at Montana State University. Montana is not quite the isolated wilderness that people think it is.

How about...

1. A flat part with a minute spirit level
2. A rad-counter (would have to contain a replaceable detector material)
3. A diamond - use to scratch glass, cars etc ;)
4. A coil of dental floss
5. An engraved protractor
6. A Cap'n Crunch decoder ring (the ring as 2+ moving parts)
7. (Tricky) make the ring resonate at an interesting frequency
8. (Old school) a signet ring
9. (Simple) marked edges - the ring can be flipped like a coin to make decisions
10. A tiny, hence probably useless, circular slide rule (link)
11. Neodymium!
12. An induction coil - for when she needs to make a quick electromagnet
13. (Cute, but not useful yet) a strand of your DNA - this way she can clone you
14. (Awful) an engraved copy of your pre-nuptial agreement ;)

There is evidence that shows dairy is unhealthy. There is no evidence showing that it *is* healthy. Find it. Marketing isn't evidence.
Well, there seems to be many people who have provided evidence, compared to the propaganda that the vegan/animal rights groups put forward. EXACTLY what I said in my original statement, that there is propaganda from both sides of the fence. It's funny how your beliefs influence what you consider marketing/propaganda, while the rest of us hear the marketspeak you use (remember, PETA has to get money from somebody too) and giggle at you parroting information provided by groups with a conflict of interest in the matters at hand.

Value is completely wrapped up in efficiency when it comes down to what is best for society.
What an empty statement! Of course lots of things apply when you want to get into hypothetical situations about what is best for society, but society rarely does the smartest thing. Maybe in fantasy-land decisions are based on environmental reasons alone, but here in the real world value, whether real or imagined, is dictated by market forces and the parties who purchase/manufacture the product. If value and efficiency where completely intertwined, nobody would buy diamonds, wood fuel would be banned, soy plots would be outlawed, etc.

Get off my back about being rude.
Why? You have a history of comments on this story alone where you are condescending and arrogant, which frustrates debate because most of your opinions are just that, with no proof. Let's look through some of your greatest hits for this thread:

you are the type who doesn't care about the survival of his or her own species

Compare the definition of redundant with the number of times this joke showed up, and you might be able to answer your own question

So since you just blabber on and don't have a clue, just stfu.

I don't drink or eat cows. Yet I still eat... amazing eh?

So here it is in what I hope is easier English for you to understand

I could go on and on where you have been rude and condescending. I never said it was to me, but by the time I wanted to reply to one of your misinformed posts I had heard enough of your attitude.

Again, your last two points go hand in hand. Firstly, your comprehension sucks. After your third attempt, you still don't realise what is being said, so i'm not going to waste any more time on dumbing it down for you. Secondly, it got personal when you've spent half the thread arguing like a prat (while completely missing the point of what people are saying) without any facts, just pushing your left-wing militant vegan propaganda bullshit onto anyone who may see things differently to your twisted world perspective. And even worse, when you COMPLETELY misunderstand where the arguments are going, people have tried to clarify this information for you while being considerate of your feelings and not trying to embarass you, yet you still miss the point and become argumentative and arrogant. I don't hold anything against you, and it is nothing personal, but if you read back through all of your comments on this thread and what people have replied it becomes quite clear that you run off half-cocked without actually reading the statements being made, you start pushing your personal preferences onto others and then have the audacity to insinuate that we are morons for not subscribing to your lifestyle choices. That is antisocial. Now, i've got some work to do, so I think this should be the end of the discussion, it's been lovely chatting.

This technique uses a concept called a Lagrange Point, where gravity from multiple bodies (usually in a orbiting situation) cancel each other out -- which results in a place where a parked object can sit and stay in place in relation to the orbiting system.

This technique is used to keep the SOHO sun observation satellite at Lagrangian point 1 in the earth/sun system, so that it keeps a constant view of the sun.

The concept behind this is extended in this instance to reveal tunnels which offer the 'path of least resistance.'

In fact, this has been discussed on Slashdot before. Slashdot users have also discussed Lagrangian points in relations to one or both of Earth's sub-moons.

There's a pretty nice explanation at this page

Try this.

L1 is about 5/6 of the way to the moon, along a direct line from the earth to the moon.

L2 is opposite the L1, over the far side of the moon from the earth.

L3 is close to the moon's orbit around the earth, but on the opposite side of the earth from the moon.

L4 and L5 are also in the orbit of the moon around the earth, but one is 60 degrees ahead of the moon in its orbit and the other is 60 degrees behind.

You can find more information at this web site and there is even more detailed information to be found here

Thats perfectly possible, assuming you are in a powered craft. Its only not possible if you are in a free-fall (non-powered) orbit.

Hold on. Do me a favour. Take a look at this site.

Then can you tell me if you think using your 23rd Century space drive to hover over the south pole meets this definition of "orbit"?

Or you can use this definition . or this one , or this one , or this one , or this one .

All your science sounds good, I just thought I would throw in this link to picture of the Lagrange Points to make it easier to understand.

Changes in global temperature couldn't possibly be due to things like ongoing cyclical climate fluctuations.

Obviously, environmentalists are always right.

More like speed, inertia, and gravity. Gravity is constanting trying to pull the ISS to the ground, the speed and inertia of the ISS keep it in orbit.

There is also such a thing as a Lagrange Point.

Kierthos

Josh Cogliati is working on a reimplementation in Python called L.A.M.B. -- Land Access Mechanized Bot. There's still a lot of work to do, tough.

Can anyone speculate how easy it would be to sustain a stable orbit around the moon for long periods of time?

There are 5 lagrange points in a two-body system such as earth-moon. The L2 point behind the moon is unstable, but a very small amount of station-keeping thrust every now and then would keep a relay satellite there.

The moon obscures L2 from earth. But you could do a second bounce off a satellite at L4 or L5. Those are 1/6th of the way around the orbit behind and ahead of the moon and are stable second order - a satellite drifts off the potential peak but then ends up in a stable orbit around it.

See an explanation here

This is you? I am impressed! Too bad for your sake that I'm not some cute blonde 19 year old impressed coed, but I am impressed all the same.... I've always wondered how you verify the discovery / recovery of a new / rare species. Usually I wonder this right when some cool looking gold-shelled beetle with emerald green eyes lands nearby and I wonder if this is a new species that I could name cybrpnkii bugii.... Please allow me to read between the lines of your postings and make a comment or two. So what if nobody else around you thinks trees are cool or even doesn't care about your solid achievements as a naturalist? What you care about IS important, whether anybody shares that with you or not, and deep inside you obviously know that. The world is full of people who don't care and own chain saws. The day that the few people like you stop caring about conservation is the day the last field gets paved over, and that will be a very bad day indeed. It's people like you who poke around under rocks in the forest (so to speak) that have given all of us the keys to genetic engineering and leads on a cure for cancer. This is important even tho the financial rewards are often lacking...So best of wishes on your wildlife pursuits, and who knows, I'm a Tennessee native (Go Vols!) living in north Alabama, if I ever bump in to you in Gatlinburg or the Smokies, the drinks are on me! -cybrpnk (rickyjames@email.com)