The article also speaks about the North-East passage, the passage across Northern Siberia. This passage has been used in the past.
I read a book on German armed merchant cruisers during World War 2.
The German merchant fleet was confined to harbour during World War 2.
About two dozen of their fastest merchant ships were refitted with cannons, mines, and mine-laying rails, and sent out to raid allied
shipping.
Large naval crews sailed aboard them. And they became really skilled at altering the ships appearance to resemble other, real, allied or neutral vessels. Some of these raiders were very successful.
Anyhow, prior to Germany attacking the Soviet Union, the Germans chartered a Soviet ice-breaker to escort one of these commerce raiders across this Northeast passage, so it could attack allied shipping in the Pacific.
You, unfortunately, are doing exactly what you accuse the poster of. Our poster is referring, offhandedly, to the extensive posting on the topic of water level changes above -- on the very same Slashdot story. S/he didn't commit to one side in that argument or the other, if you'd kindly read the actual words rather than what you assumed they said. The rest of this post, the guts, is about temperate change, ocean currents, and potential effects on climate in places like Europe... or did you get that far?
You might want to read the message and respond thoughtfully to it -- rather than choosing to use an aside as a straw man to try to score debate points against. This is a pretty classic Usenet tactic, and all it does is expose your prejudices.
Mr Scot, I did read Samuel's original post. I read the whole thing. I read it several times. And after reading your comment I went back and re-read it.
Anyone who just read your comment would think I am a troll who posts flamebait. That bugs me.
You seem to be scolding me for taking the original comment out of context.
Well, Samuel's comment starts a new thread. It is not a followup to any previous comment. So far as I am concerned there is no context.
What prejudices of mine do you think I am exposing, anyhow?
Are you assuming that since I challenged part of Samuel's post I am challenging the idea Global Warming is a serious problem? You seem to be assuming this is obvious.
Global warming has come up in several threads this year. And in those discussions I have spent hours researching
links to post that demonstrate that it is a terribly serious problem.
But, I don't think that I do the views I agree with a favour by refraining to challenge something that is clearly wrong merely because another part of that comment may agree with my views.
The British had a blue ribbon committee look into the Titanic's design.
The Titanic's watertight bulkheads were all transverse, from Port to Starboard. The committee suggested that Titanic would have fared better if she had also had one longitudinal bulkhead.
Five years later the Lusitania is sunk by a torpedo, with considerable
loss of life. The British had a blue ribbon committee look into her
design. They suggested that there would have been less loss of life if
she had not had a longitudinal watertight bulkhead.
My recollection is that some of the same people sat on both committees.
As water filled up some of the compartments on one side, the ship started to list to one side. Once she was listing more than, IIRC, fifteen degrees, then passengers couldn't jump across to the lifeboats on the lower side. And while passengers could enter the life boats on the higher side, lowering them was a problem, because they slid down the side of the ship, and in those days the hull plates were sealed with big rivets. The boat deck was sixty feet from the water. Those rivets tore the lifeboats to peices.
If you followed the talk about how much a melting ice cube raises the water in a glass...
I'm sorry, you
are confident and think you know what you are talking
about. But you actually have no idea.
American humourist Will Rogers said something like, "It is not what
you don't know that is the biggest problem, it is what you know
that just ain't so."
Melting ice floating in water does not raise the
water level. If the ice is floating, it is displacing an equal
weight of water. Ice is less dense than water, at 0 degrees.
So it floats. This is called buoyancy. Melting ice will not raise the water level even
one nanometer.
The St Roch was the second vessel to traverse the Northwest passage.
She did it first West to East, and then from East to West. She was
also the first vessel to circumnavigate North America.
The St Roch's first voyage, in 1942, was extremely dangerous.
It took over two years. She was frozen in the ice over two winters.
And she was almost crushed several times, when she entered a clear
channel through the ice pack. Combinations of currents, tide and wind would clear a temporary channel. But on several occasions the changing combination of current, tide and wind would close it up after her or around her. These chunks of ice would have been closer to the size
of a bus, rather than the size of a mountain or big hill, like an
iceberg. But, being caught in a floating pack of them, with waves,
would have ground her apart.
The RCMP recreated the St Roch's traverse, as a millenial celebration.
They encountered practically no ice. The RCMP sent a small, modern patrol vessel to do the recreation. And the Canadian Coast Guard sent
an ice-breaker as an escort. This time around the ice-breaker was
never needed.
The original St Roch is the core of the Vancouver Maritime Museum.
She is a wooden vessel, about 100 tons. Her hull is dish-shaped,
and specially reinforced, so that if the water froze around her
she would pop out, like a cork, rather than being crushed.
Okay, that was the clearly on topic part of this comment.
The
Larsen B ice shelf that fragmented down in Antarctica in
April is named after Henry Larsen, the St Roch's commander.
The St Roch was an RCMP vessel. During the thirties she ferried
personnel and supplies to the RCMP's more distant northern
stations. In those days a few dozen RCMP officers were just
about the only presence of the Canadian government up there.
The St Roch only had a crew of ten or so. Larsen was only a
sergeant. But it was felt necessary to send them on this
dangerous and arduous journey, during the war. The Germans
did establish weather stations on Northern Islands. This
was extremely important in the days before weather satellites.
If they had established bases in Greenland, or Canada's Eastern
Arctic, a vessel like the St Roch would have been useful to
track them down. But many believe the real mission was to
protect Canadian soveriegnty over the far north, from the
Americans.
The Americans building the Alaska highway, across BC and the
Yukon, were bullying the locals, acting like Canada was an
occupied country, and they were the only legitimate authority.
In this they were a very bad ally.
During a slashdot discussion earlier this year we came across an NPR interview with a scientist who was an expert on permafrost. He said
that permafrost can be hundreds of metres thick. Permafrost is like a
huge, frozen bog. As it melts, and biological activity recommences,
it will release huge quantities of methane and CO2.
I forget exactly how the carbon locked up in permafrost compared
with the amount of CO2 in the atmosphere. But it was frightening.
Mars will then be 100 times further than the moon from our planet. The moon is about 350,000 miles from earth, and mars will be about 35 million. It took about 3 days to get to the moon, on the Apollo 8 Mission.
This means it would take about 300 days to get to Mars, one way (assuming similar rates of travel). I guess you could use more fuel in the beginning to get a higher inital velocity and maybe cut that time down.
Woah cowboy!
If you are using a traditional rocket, not a Star Trek warp drive, the route from Earth to Mars is not a straight line.
Draw two concentric circles on a piece of paper, representing the orbits of the Earth and Mars. Now imagine an ellipse, with one foci the same as the focus of the two concentric circles. If you adjust the size of that ellipse so that it is tangent to the inner circle at one end, and tangent to the outer circle at the other end, I believe that ellipse would represent the minimum fuel path to Mars orbit.
If you follow this route you won't travel 35 million miles, you will travel something like a bit more than 300 million miles. How long will it take? There are 365 days in an Earth year, and IIRC about 650 Earth days in a Martian year. An object following that elliptical route from the Earth's orbit to Mars's orbit would take something like 500 days to complete its own orbit around the Sun. So about 250 days, which is close to your guess, but only coincidentally.
Of course arriving at Mars orbit isn't enough. You have to schedule your launch from the Earth so you arrive there at the point where you are tangent to Mars's orbit when Mars is at that point in its orbit.
This is further complicated by the orbit of the Earth and Mars not being circular. They are ellipses too. The Earth's distance from the Sun varies by 2 or 3 percent throughout the year. I don't know whether the bulges in their respective orbits are close to one another, or on opposite sides of their orbits.
250 days? So if the bulges in orbits lined up, your ideal launch window would be when the Earth was at its farthest distance from the sun, and Mars was 250 days away from its closest distance from the Sun. The probe should arrive not when we are at our closest approach to Mars, but when the Earth has travelled about 60 degrees past the point where Mars meets the probe -- about 100 million miles.
If the bulges don't line up, it gets even more complicated. Which orbit is less circular matters. And the greater gravitational attraction the probe will experience when it is closer to the Sun also plays a factor.
Since I know next to nothing about hardcore physics, I have to ask: how long do we think it took for "mostly hydrogen, some helium, and a little lithium" to be converted into all of the naturally occuring elements of today?
I am not an astrophysicist. But I think I can tell you where the other elements are made, and how they are spread.
I believe the short answer is supernovae.
The fusion of atomic nuclei of the elements low on the periodic table generates energy. The Fusion of Hydrogen to Helium generates the most energy per nuclei produced. And it happens at a lower pressure and temperature. The energy produced keeps the gas hot enough that gravity does not pull the star into a denser ball.
As time goes by, and Hydrogen is fused to Helium, the star's core starts to become mainly Helium. At high enough temperatures and pressures the Helium starts to fuse, and the innermost core gets composed of those elements.
Iron is the element where Fusion no longer produces energy, but rather
takes energy. In stars like our Sun, that is all that happens, eventually all the fuel that is at a temperature and pressure dense enough to fuse has fused, and the star goes dim.
Note, all the really common elements we find here on earth, in the atmosphere, on in the Earth's crust, are the elements that are lighter than Iron, like Silicon, Aluminum, Oxygen, and so on.
The smaller a star is, the more miserly it fuses, and the longer it lasts. Large stars burn quickly, much more quickly.
Stars that are larger than, um, 1.5 times the mass of the Sun, IIRC,
are large enough that when all the fuel in the core has fused, they
go supernovae. This generates as much energy as the rest of a Galaxy
like our own. That is a terrific amount of energy. There is enough energy there to fuse the Iron and other metals into Gold, Silver, Lead, Palladium, Plutonium, Californium, and Unobtainium. And there is enough energy to blow some portion of the star away in a huge blast wave. That shell of star detritus contains some of those higher elements. That shell is travelling far less than the speed of light, but pretty fast by celestial standards. And as it expands and dissipates, it leavens star forming dust clouds with the higher elements.
Really big stars don't last billions of years, like the Sun, they last only a billion years or so. And really, really big stars, would last even shorter times. So how long would it take for a galaxy sized gas cloud that already had some metal poor stars form to get sprinkled
with metals, for the next generation of stars that have some metals?
Jeez, I don't know. I am not an Astrophysicist. Okay, okay, my wild guess... Well let's see, our Galaxy is 100,000 lightyears across. How fast does that shell of detritus shoot out from the supernovae? 1% the speed of light? 0.1% the speed of light? 0.01% the speed of
light? But the detritus doesn't have to spread through the entire
galaxy, because there would be lots of Supernovae. We have three
per 1000 years now. Who knows what the rate was then? But, let's
say it was the same as now. Once they start popping off (100 million years?) a few tens of millions of years and we would have tens of
thousands of supernovae blast waves leavening all those star forming dust clouds.
What happens when a dust cloud that has some metals, but not many, forms a stellar system? Do you still get planets the size of
Jupiter? Or do all the planets get downscaled, so instead of Jupiters you get Neptunes? Would the inner planets get downscaled too? Or maybe you just get inner planets, of similar sizes to ours, and no big gas bag planets at all?
I'd like to know this. Of the 100 or so stellar systems Astronomers think they have detected nearby I believe all the planets detected have been big gas bags. Some of them were 10x the size of Jupiter. And some of them were quite close their Primaries. Before they found those close-in big gas bag planets, didn't Astronomers think big gas bags only formed out where it was cooler?
Yeah, but the challenge I was mounting was to the previous poster's
assertion that IE loaded more quickly. By that I assumed he/she
meant the time from invocation to it being ready to do your bidding.
due to disk caching, OS integration,
Cheating, in my books. I want to control which, if any, applications
get preferential access to system resources.
etc. But Phoenix is faster than both without any of that. Go take it for a test drive.
Woah cowboy! Let me feel I have mastered Mozilla first, OK?
IE6 feels light and it looks like a Windows program. Plus, it loads more quickly.
Is this true? Can I express skepticism? A friend of mine asked me
to purchase a copy of the most recent MS office suite for her under
the academic discount, in the fall of 1999. I stayed with her, and
used her computer, over the Christmas holidays. Youch, it was
painful. Her computer took forever to boot. And, if you invoked
any non-microsoft programs you could hear the HDD thrash like crazy.
I looked into this, and thought I confirmed that the MS
office suite was to blame. I thought the reason it took forever to
boot was because MS fired up all the office applications first.
I thought the reason the HDD thrashed like crazy was that MS gave
the office suite products preferential access to the windows swap
space, loading them back in, even though they weren't in use, so
that the OS could continue to invoke them quickly, in spite of their
huge, bloated size.
So, are you really sure IE invokes more quickly?
Re:Convince Me [tabbed browsing holds value]
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Phoenix 0.4 Released
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Ok let me ask something. In Windows there is what we call "The task bar (tm)". With "The task bar", every window has a tab.
Now what is the use of having these tabs in a bar in the browser window, instead of having them in "The task bar" hmmm ?
As previous posters have observed, you have obviously never used a
browser with tabs.
It is useful. It makes it easier to do more than one thing at a time.
If you have a window devoted to your yahoo mail, and one devoted to
the main slashdot page, you can open each story that interests you
in a browser window of its own. Then the links withing that story you
open up into a tab of that window. If you have decided
you have had enough of that story, you can close its browswer window,
and all its tabs, all at once. This is very convenient. It makes it
easy to go back and forth between the article and the sidebar.
Tabbed windows makes it less painful if you still have a dialup link.
I use yahoo mail as my visible mail address. Over a dialup link it can
take a while to download my mail. So I download each one into a tab
of its own, leaving the list of mail messages in the original tab.
Then I can go do something else, like fire up slashdot. By the time
I have done that, my mail is ready for me to read. Once I have read
them all I right-click on the tab that contains the list of mail
messages, and I select "close all other tabs". Easy.
You might think that you could do the same thing, just as easily in
IE. But you would be wrong. Sure, IE would let you open up a full
window for every mail message. And if you read them in last in,
first out order,
and closed each one when you had read the message, you would
eventually be brought back to the window with the list of articles.
But, in IE you would have to wait for the last window to load. And
if you visited your slashdot window(s) while you were waiting, the
order of your windows would be all screwed up.
Jeez, way to confirm all the worst stereotypes gals have about us guys!
Sheesh. Our hero knows a gal, who is a friend, who is
really interested in Science. How often does that happen?
Maybe she liked him well enough to
not look ascance if he made an overture? Or maybe she just thought she
knew she could trust him?
In my opinion, he should be honoured, either way. He is a lucky guy.
And he had an opportunity to be awed by the immensity of the Universe.
This is the kind of memory one treasures for the rest of one's life.
It sounds to me as if he was lucky that being awestruck induced him
to forget to try to "score". That
wouldn't have been nearly as memorable. And, if he does try to get
her to take the relationship to an intimate level, they will already
have a really special shared memory.
My advice would be not to let the comments of the others here cheapen
that memory.
WTF are they talking about when they say "horseshoe" orbit. Doesn't look the least bit horseshoe like to me...
Go back to the JPL thing, and make it have its point of view focus on the Earth. Now look at the line that represents 2002 AA29's orbit? But 2002 AA29's orbital path ranges over a kind of ribbon, because the Earth speeds it up and slows it down, as explained here.
So think of a picture centered on the Earth. 2002 AA29 approaches Earth, but it doesn't come too close. So if you map its location, relative to the Earth, the two horns of the horseshoe shape represent its closest approach when leading and when trailing the Earth. The rest of the time it is somewhere in that ribbon.
Its period around the Sun, its year, varies in length, when the Earth has slowed it down, it is closer to the Sun. That bounds the inner part of the horseshoe shape. When the Earth has sped it up, that bounds the outer part of the horseshoe shape.
Of course, the part I don't get, *why* can't it hit the Earth? In roughly the same orbit around the sun, a much smaller mass has to travel MUCH slower than the Earth to maintain that orbit...
I don't have the equation for the gravitational attraction between two bodies. But I know it is a function of the SUM of the masses of the two objects. So, how much do you think the sum of the masses of the sun and the Earth differs from the sum of the masses of the sun and 2002 AA29?
There are lots of explanations of horseshoe orbits on the web. Basically, if two objects share the same, or very similar, orbits, they are attracted to one another. That gravitational attraction drains kinetic energy from the leading object, and slightly adds kinetic energy to the trailing object.
The leading object, having lost energy, moves closer to the primary. Its year gets slightly shorter, and its actual velocity relative to the primary speeds up. Similarly, the trailing object moves farther away, and its year grows slightly longer.
So the leading objects closer orbit has it revolve around the Primary more quickly, and it will slowly move away from the trailing object. Eventually the leading object is exactly opposite from the trailing object. According to the BBC article, this takes 95 years.
Once the object that was leading is more than 180 degrees ahead in it orbit from the object that was trailing, their mutual attraction starts to add energy to its orbit, and raise it to a higher orbit. Similarly, the mutual attraction drains energy from the other object.
What we have just seen is the two objects trade places. The object that was the trailing object is now the trailing object.
It seems paradoxical that mutual attraction should tear the two object apart. Until you remember that the Sun's influence on the object's trajectories is much more important than their attraction to one another.
At least that is my understanding of the BBC's article.
How does this mechanism allow 2002 AA29 to be briefly captured by the Earth? I'd welcome an explanation of this.
Who is general failure, and why is he trying ...
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Gnarly Error Messages
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Who is general failure, and why is he trying to read my drive?
I didn't make this up. I saw it in someone else's signature file.
Obviously a response to the MS error message:
PBS broadcast a very funny documentary on the Florida voting scandal on the 17th.
It provided more details about Jeb and company buying lists of felons. (Felons can't vote in Florida, even when they have served their full sentence.) One of the returning officers described what it was like to be banned from voting because this list was wildly inaccurate.
The designer [of the butterfly ballot] was a Democrat, but had worked many years as an election official, so it wasn't really that she was incompetent. She just screwed up once. The point is, there was no intent to "defraud" voters.
Peter Neumann, the moderator of the long-running RISKS digest, said that
a previous Florida election had been ruined by the use of these voting machines.
The really sad thing is that many of the same punch-card machines
were apparently also implicated in the 1988 Florida Senate race.
Buddy Mackay lost a close election to Connie Mack, in which there was
a drop-off of 210,000 votes relative to the Presidential race in the
same four counties. A lot of people must have been asleep at the wheel.
That sounds like two screw-ups to me. And if she had working as an election official since 1971 it is hard to imagine how she couldn't have known of the previous scandal.
make: stop. don't know how to make love!
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Gnarly Error Messages
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· Score: 5, Funny
...that featured the following error msg:
I must remember to put an error message here
I read a case history that was somewhat similar. Except the error message was in Latin. Someone who had once taken Latin was tracked down,
and asked to translate. The translation was something like, "Unto the son is born a brother". When the original programmer was tracked down, he was embarrassed. "But that condition was never supposed to arrive. He had some kind of complicated data structure, where each element could have children and siblings. Except the element at the apex of the tree was supposed to be a special case -- no siblings.
But since it was never supposed to happen the original programmer didn't bother to put a meaningful error message.
Back with good old version 7, make gave error messages like:
make: stop. don't know how to make foo!
if you had typed "make foo" and there was no makefile, or
no rule for foo in the makefile.
When computer naive people (remember them) would ask what computers could do, it was fun to have them sit down and type:
There is a practical limit to the size of animals. Their weight goes up as the cube of their dimensions. But the strength of their bones goes up only by the square of their dimensions. It puts a practical limit on the size of flying creatures.
Isaac Asimove wrote one of his science essays on this. I remember reading it as a kid. I remember he calculated that a winged horse, like Pegasus, would need a wingspan of 200 feet -- just like the Gossamer Condor.
One of the Alaskans compared the mystery bird to a
Twin Otter.
"At first I thought it was one of those old-time Otter planes," Coupchiak said. "Instead of continuing toward me, it banked to the left, and that's when I noticed it wasn't a plane."
The bird was "something huge," he said. "The wing looks a little wider than the Otter's, maybe as long as the Otter plane."
The Otter's wingspan is 65 feet for crying out loud.
Well, Nasa has stopped their ISS crew rescue vehicle program last year for cost reasons. See here.
Thanks for the info. I found some
additional information.
There was some talk of using
this gold-plated mini-shuttle as the rescue vehicle.
Then
this design
was being worked on. Even though its budget was, as Lars pointed
out, cut for 2002, they still test launched it as recently as December 2001.
This link has some info on the use of
the Soyuz as the rescue vehicle.
I hadn't realized that US budget decisions had cut the ISS back to a skeleton crew. Here is a press release from a US Senator commenting on a recently released independent review of the Space Station's Science programs.
The reason these things all wind up looking the same is simple: Math.
In doing similar tasks, the same engineering problems present themselves.
Buran, the Soviet shuttle, has been discussed here on slashdot in the past. I spent most of an afternoon following some links other slashdotters had provided to details of Buran's design.
I found it fascinating. They do look similar. But there were some important differences, under the skin.
One of the web-pages discussed the similarity in appearance of Buran and the American shuttles. It said that Soviet engineers had considered a number of hull designs, with differing appearances. The other hulls looked, on paper, as if they would be just as successful as the American hull design. IIRC the only advantage of the American hull design was that it was a proven design.
The American shuttle uses strap on boosters fueled with solid fuel. Buran's boosters are liquid fueled, and it could strap on three of them. Consequently, it had a much larger lift capacity than the American shuttle.
Buran's crew, at least four of them, were protected by ejection seats.
It has been a year or two since I read these pages. I may not remember them correctly. But wouldn't Buran's liquid fueled boosters be innately safer than the American shuttle. Solid fueled rockets can't be shut down. If the challenger had liquid fueled boosters, would they have been able to shut down the booster, and have a greater chance of survival? Liquid fueled boosters wouldn't have had the dangerous "O ring" feature.
...if they hope to bring any kind of sizeable payload into space, it's going to have to be one mamba-jamba of an engine, unless they have very tiny sattelites...
I asked this elsewhere. How many shuttle missions leave with a full payload? I believe that Hubble filled the cargo bay, as did the various ISS modules, and the European Spacelab. But doesn't that leave dozens of missions with partially loaded cargo bays?
I seem to recall hearing that Russia was having big financial problems with their space program, and that if they didn't scrape up funding in some form, that it may adversely impact the long term construction plans for the ISS over the next few years.
Yeah. The ISS has a Soyuz docked to it, to serve as a lifeboat, if the ISS suffers a disastrous failure. The Soyuz can fit three spacesuits, so when the shuttle leaves they only leave three scientists aboard the shuttle at any one time.
Well, the Soyuz isn't left there permanently. They loft a new one every six months or so. So, if the Russians pack up their Space program either the ISS inhabitants have to get left there with no lifeboat, or a substitute has to be designed.
How difficult would designing a return module be? It wouldn't have to be as robust or sophisticated as a Soyuz, Apollo or Gemini, if its sole
purpose was to serve as a lifeboat. It could be brought to the ISS by a shuttle, so it wouldn't need to control the one shot rocket that launched it. And, it wouldn't require the endurance of an Apollo or Soyuz. Its mission would last less than an hour or two. It would only have to endure long enough to bring the ISS researchers back to Earth.
It was miscalculation of cost that resulted into US space shuttle (they thought that the reusability of space shuttle boosters will make it cheaper than traditional rockets).
I read, a long time ago, that the US shuttle's design incorporates
features to serve the USAF, or reasonable equivalent. The story, as I read it, was that NASA didn't think it could get the funding to build the shuttle if it didn't have allies inside the Beltway. Elements in the Defense department agreed to endorse the shuttle, provided they got input into its design. The large size of the shuttle was given as one of those compromises. The suggestion was that if NASA had been allowed to build a shuttle without design compromises, it would have been more successful.
I'd welcome knowledgeable comments on this story. Sorry, I can't remember where I read it.
As it turned out, the US military doesn't use the shuttle, do they? Don't they use the old one-shot rockets?
Why does the shuttle have to be so big? Okay, Hubble, and the various ISS modules more or less fill the shuttle bay. But there have been something like 100 shuttle missions so far, how many of those missions had payloads that fully filled the cargo bay? They could all have been launched with big one-shot rockets, couldn't they? The 197?s Skylab was launched by a surplus Saturn V wasn't it?
The Hubble repair missions could have been mounted from a more modestly sized shuttle, couldn't they?
I read, something interesting back during the first years of Hubble's deployment, back before its optics were corrected, and everything was out of focus. NASA cut corners. They tested all the pieces separately, on the ground. But they didn't test the fully assembled telescope on the ground. I read that they considered doing so, but it required the construstion of a test jig. The test jig would have been expensive, and the decision was made to gamble.
The story was that the US already possessed a test jig suitable for testing large space telescopes. But NASA couldn't use it, because it was top secret, because it was used to test the large telescopes of top secret spy satellites, which were focussed on the Earth.
Can anyone debunk this story? If true, those satellites must have been launched by one-shot rockets.
Slashdot Mirror
I read a book on German armed merchant cruisers during World War 2. The German merchant fleet was confined to harbour during World War 2. About two dozen of their fastest merchant ships were refitted with cannons, mines, and mine-laying rails, and sent out to raid allied shipping.
Large naval crews sailed aboard them. And they became really skilled at altering the ships appearance to resemble other, real, allied or neutral vessels. Some of these raiders were very successful.
Anyhow, prior to Germany attacking the Soviet Union, the Germans chartered a Soviet ice-breaker to escort one of these commerce raiders across this Northeast passage, so it could attack allied shipping in the Pacific.
Mr Scot, I did read Samuel's original post. I read the whole thing. I read it several times. And after reading your comment I went back and re-read it.
Anyone who just read your comment would think I am a troll who posts flamebait. That bugs me.
You seem to be scolding me for taking the original comment out of context.
Well, Samuel's comment starts a new thread. It is not a followup to any previous comment. So far as I am concerned there is no context.
What prejudices of mine do you think I am exposing, anyhow?
Are you assuming that since I challenged part of Samuel's post I am challenging the idea Global Warming is a serious problem? You seem to be assuming this is obvious.
Global warming has come up in several threads this year. And in those discussions I have spent hours researching links to post that demonstrate that it is a terribly serious problem.
But, I don't think that I do the views I agree with a favour by refraining to challenge something that is clearly wrong merely because another part of that comment may agree with my views.
Five years later the Lusitania is sunk by a torpedo, with considerable loss of life. The British had a blue ribbon committee look into her design. They suggested that there would have been less loss of life if she had not had a longitudinal watertight bulkhead.
My recollection is that some of the same people sat on both committees.
As water filled up some of the compartments on one side, the ship started to list to one side. Once she was listing more than, IIRC, fifteen degrees, then passengers couldn't jump across to the lifeboats on the lower side. And while passengers could enter the life boats on the higher side, lowering them was a problem, because they slid down the side of the ship, and in those days the hull plates were sealed with big rivets. The boat deck was sixty feet from the water. Those rivets tore the lifeboats to peices.
I'm sorry, you are confident and think you know what you are talking about. But you actually have no idea.
American humourist Will Rogers said something like, "It is not what you don't know that is the biggest problem, it is what you know that just ain't so."
Melting ice floating in water does not raise the water level. If the ice is floating, it is displacing an equal weight of water. Ice is less dense than water, at 0 degrees. So it floats. This is called buoyancy. Melting ice will not raise the water level even one nanometer.
The St Roch's first voyage, in 1942, was extremely dangerous. It took over two years. She was frozen in the ice over two winters. And she was almost crushed several times, when she entered a clear channel through the ice pack. Combinations of currents, tide and wind would clear a temporary channel. But on several occasions the changing combination of current, tide and wind would close it up after her or around her. These chunks of ice would have been closer to the size of a bus, rather than the size of a mountain or big hill, like an iceberg. But, being caught in a floating pack of them, with waves, would have ground her apart.
The RCMP recreated the St Roch's traverse, as a millenial celebration. They encountered practically no ice. The RCMP sent a small, modern patrol vessel to do the recreation. And the Canadian Coast Guard sent an ice-breaker as an escort. This time around the ice-breaker was never needed.
The original St Roch is the core of the Vancouver Maritime Museum. She is a wooden vessel, about 100 tons. Her hull is dish-shaped, and specially reinforced, so that if the water froze around her she would pop out, like a cork, rather than being crushed.
Okay, that was the clearly on topic part of this comment.
The Larsen B ice shelf that fragmented down in Antarctica in April is named after Henry Larsen, the St Roch's commander. The St Roch was an RCMP vessel. During the thirties she ferried personnel and supplies to the RCMP's more distant northern stations. In those days a few dozen RCMP officers were just about the only presence of the Canadian government up there.
The St Roch only had a crew of ten or so. Larsen was only a sergeant. But it was felt necessary to send them on this dangerous and arduous journey, during the war. The Germans did establish weather stations on Northern Islands. This was extremely important in the days before weather satellites. If they had established bases in Greenland, or Canada's Eastern Arctic, a vessel like the St Roch would have been useful to track them down. But many believe the real mission was to protect Canadian soveriegnty over the far north, from the Americans.
The Americans building the Alaska highway, across BC and the Yukon, were bullying the locals, acting like Canada was an occupied country, and they were the only legitimate authority. In this they were a very bad ally.
I forget exactly how the carbon locked up in permafrost compared with the amount of CO2 in the atmosphere. But it was frightening.
Yup. Proof enough for me.
Except the link in dmaxwell's article has typos. This version works.
Woah cowboy!
If you are using a traditional rocket, not a Star Trek warp drive, the route from Earth to Mars is not a straight line.
Draw two concentric circles on a piece of paper, representing the orbits of the Earth and Mars. Now imagine an ellipse, with one foci the same as the focus of the two concentric circles. If you adjust the size of that ellipse so that it is tangent to the inner circle at one end, and tangent to the outer circle at the other end, I believe that ellipse would represent the minimum fuel path to Mars orbit.
If you follow this route you won't travel 35 million miles, you will travel something like a bit more than 300 million miles. How long will it take? There are 365 days in an Earth year, and IIRC about 650 Earth days in a Martian year. An object following that elliptical route from the Earth's orbit to Mars's orbit would take something like 500 days to complete its own orbit around the Sun. So about 250 days, which is close to your guess, but only coincidentally.
Of course arriving at Mars orbit isn't enough. You have to schedule your launch from the Earth so you arrive there at the point where you are tangent to Mars's orbit when Mars is at that point in its orbit.
This is further complicated by the orbit of the Earth and Mars not being circular. They are ellipses too. The Earth's distance from the Sun varies by 2 or 3 percent throughout the year. I don't know whether the bulges in their respective orbits are close to one another, or on opposite sides of their orbits.
250 days? So if the bulges in orbits lined up, your ideal launch window would be when the Earth was at its farthest distance from the sun, and Mars was 250 days away from its closest distance from the Sun. The probe should arrive not when we are at our closest approach to Mars, but when the Earth has travelled about 60 degrees past the point where Mars meets the probe -- about 100 million miles.
If the bulges don't line up, it gets even more complicated. Which orbit is less circular matters. And the greater gravitational attraction the probe will experience when it is closer to the Sun also plays a factor.
I am not an astrophysicist. But I think I can tell you where the other elements are made, and how they are spread.
I believe the short answer is supernovae.
The fusion of atomic nuclei of the elements low on the periodic table generates energy. The Fusion of Hydrogen to Helium generates the most energy per nuclei produced. And it happens at a lower pressure and temperature. The energy produced keeps the gas hot enough that gravity does not pull the star into a denser ball.
As time goes by, and Hydrogen is fused to Helium, the star's core starts to become mainly Helium. At high enough temperatures and pressures the Helium starts to fuse, and the innermost core gets composed of those elements.
Iron is the element where Fusion no longer produces energy, but rather takes energy. In stars like our Sun, that is all that happens, eventually all the fuel that is at a temperature and pressure dense enough to fuse has fused, and the star goes dim.
Note, all the really common elements we find here on earth, in the atmosphere, on in the Earth's crust, are the elements that are lighter than Iron, like Silicon, Aluminum, Oxygen, and so on.
The smaller a star is, the more miserly it fuses, and the longer it lasts. Large stars burn quickly, much more quickly.
Stars that are larger than, um, 1.5 times the mass of the Sun, IIRC, are large enough that when all the fuel in the core has fused, they go supernovae. This generates as much energy as the rest of a Galaxy like our own. That is a terrific amount of energy. There is enough energy there to fuse the Iron and other metals into Gold, Silver, Lead, Palladium, Plutonium, Californium, and Unobtainium. And there is enough energy to blow some portion of the star away in a huge blast wave. That shell of star detritus contains some of those higher elements. That shell is travelling far less than the speed of light, but pretty fast by celestial standards. And as it expands and dissipates, it leavens star forming dust clouds with the higher elements.
Really big stars don't last billions of years, like the Sun, they last only a billion years or so. And really, really big stars, would last even shorter times. So how long would it take for a galaxy sized gas cloud that already had some metal poor stars form to get sprinkled with metals, for the next generation of stars that have some metals?
Jeez, I don't know. I am not an Astrophysicist. Okay, okay, my wild guess... Well let's see, our Galaxy is 100,000 lightyears across. How fast does that shell of detritus shoot out from the supernovae? 1% the speed of light? 0.1% the speed of light? 0.01% the speed of light? But the detritus doesn't have to spread through the entire galaxy, because there would be lots of Supernovae. We have three per 1000 years now. Who knows what the rate was then? But, let's say it was the same as now. Once they start popping off (100 million years?) a few tens of millions of years and we would have tens of thousands of supernovae blast waves leavening all those star forming dust clouds.
What happens when a dust cloud that has some metals, but not many, forms a stellar system? Do you still get planets the size of Jupiter? Or do all the planets get downscaled, so instead of Jupiters you get Neptunes? Would the inner planets get downscaled too? Or maybe you just get inner planets, of similar sizes to ours, and no big gas bag planets at all?
I'd like to know this. Of the 100 or so stellar systems Astronomers think they have detected nearby I believe all the planets detected have been big gas bags. Some of them were 10x the size of Jupiter. And some of them were quite close their Primaries. Before they found those close-in big gas bag planets, didn't Astronomers think big gas bags only formed out where it was cooler?
Isn't IE part of the MS Office Suite?
Yeah, but the challenge I was mounting was to the previous poster's assertion that IE loaded more quickly. By that I assumed he/she meant the time from invocation to it being ready to do your bidding.
Cheating, in my books. I want to control which, if any, applications get preferential access to system resources.
Woah cowboy! Let me feel I have mastered Mozilla first, OK?
Is this true? Can I express skepticism? A friend of mine asked me to purchase a copy of the most recent MS office suite for her under the academic discount, in the fall of 1999. I stayed with her, and used her computer, over the Christmas holidays. Youch, it was painful. Her computer took forever to boot. And, if you invoked any non-microsoft programs you could hear the HDD thrash like crazy.
I looked into this, and thought I confirmed that the MS office suite was to blame. I thought the reason it took forever to boot was because MS fired up all the office applications first. I thought the reason the HDD thrashed like crazy was that MS gave the office suite products preferential access to the windows swap space, loading them back in, even though they weren't in use, so that the OS could continue to invoke them quickly, in spite of their huge, bloated size.
So, are you really sure IE invokes more quickly?
As previous posters have observed, you have obviously never used a browser with tabs.
It is useful. It makes it easier to do more than one thing at a time. If you have a window devoted to your yahoo mail, and one devoted to the main slashdot page, you can open each story that interests you in a browser window of its own. Then the links withing that story you open up into a tab of that window. If you have decided you have had enough of that story, you can close its browswer window, and all its tabs, all at once. This is very convenient. It makes it easy to go back and forth between the article and the sidebar.
Tabbed windows makes it less painful if you still have a dialup link.
I use yahoo mail as my visible mail address. Over a dialup link it can take a while to download my mail. So I download each one into a tab of its own, leaving the list of mail messages in the original tab. Then I can go do something else, like fire up slashdot. By the time I have done that, my mail is ready for me to read. Once I have read them all I right-click on the tab that contains the list of mail messages, and I select "close all other tabs". Easy.
You might think that you could do the same thing, just as easily in IE. But you would be wrong. Sure, IE would let you open up a full window for every mail message. And if you read them in last in, first out order, and closed each one when you had read the message, you would eventually be brought back to the window with the list of articles. But, in IE you would have to wait for the last window to load. And if you visited your slashdot window(s) while you were waiting, the order of your windows would be all screwed up.
Not every slashdot reader is an American. So, as a courtesy, how about explaining this pledge, and this controversial addition?
I have been wondering what I should ask of my Member of Parliament, when I write to him about Microsoft.
Maybe she liked him well enough to not look ascance if he made an overture? Or maybe she just thought she knew she could trust him?
In my opinion, he should be honoured, either way. He is a lucky guy.
And he had an opportunity to be awed by the immensity of the Universe. This is the kind of memory one treasures for the rest of one's life. It sounds to me as if he was lucky that being awestruck induced him to forget to try to "score". That wouldn't have been nearly as memorable. And, if he does try to get her to take the relationship to an intimate level, they will already have a really special shared memory.
My advice would be not to let the comments of the others here cheapen that memory.
Go back to the JPL thing, and make it have its point of view focus on the Earth. Now look at the line that represents 2002 AA29's orbit? But 2002 AA29's orbital path ranges over a kind of ribbon, because the Earth speeds it up and slows it down, as
explained here
So think of a picture centered on the Earth. 2002 AA29 approaches Earth, but it doesn't come too close. So if you map its location, relative to the Earth, the two horns of the horseshoe shape represent its closest approach when leading and when trailing the Earth. The rest of the time it is somewhere in that ribbon.
Its period around the Sun, its year, varies in length, when the Earth has slowed it down, it is closer to the Sun. That bounds the inner part of the horseshoe shape. When the Earth has sped it up, that bounds the outer part of the horseshoe shape.
I don't have the equation for the gravitational attraction between two bodies. But I know it is a function of the SUM of the masses of the two objects. So, how much do you think the sum of the masses of the sun and the Earth differs from the sum of the masses of the sun and 2002 AA29?
There are lots of explanations of horseshoe orbits on the web. Basically, if two objects share the same, or very similar, orbits, they are attracted to one another. That gravitational attraction drains kinetic energy from the leading object, and slightly adds kinetic energy to the trailing object.
The leading object, having lost energy, moves closer to the primary. Its year gets slightly shorter, and its actual velocity relative to the primary speeds up. Similarly, the trailing object moves farther away, and its year grows slightly longer.
So the leading objects closer orbit has it revolve around the Primary more quickly, and it will slowly move away from the trailing object. Eventually the leading object is exactly opposite from the trailing object. According to the BBC article, this takes 95 years.
Once the object that was leading is more than 180 degrees ahead in it orbit from the object that was trailing, their mutual attraction starts to add energy to its orbit, and raise it to a higher orbit. Similarly, the mutual attraction drains energy from the other object.
What we have just seen is the two objects trade places. The object that was the trailing object is now the trailing object.
It seems paradoxical that mutual attraction should tear the two object apart. Until you remember that the Sun's influence on the object's trajectories is much more important than their attraction to one another.
At least that is my understanding of the BBC's article.
How does this mechanism allow 2002 AA29 to be briefly captured by the Earth? I'd welcome an explanation of this.
I didn't make this up. I saw it in someone else's signature file. Obviously a response to the MS error message:
General Failure reading drive a:
PBS broadcast a very funny documentary on the Florida voting scandal on the 17th.
It provided more details about Jeb and company buying lists of felons. (Felons can't vote in Florida, even when they have served their full sentence.) One of the returning officers described what it was like to be banned from voting because this list was wildly inaccurate.
Peter Neumann, the moderator of the long-running RISKS digest, said that a previous Florida election had been ruined by the use of these voting machines.
That sounds like two screw-ups to me. And if she had working as an election official since 1971 it is hard to imagine how she couldn't have known of the previous scandal.
I read a case history that was somewhat similar. Except the error message was in Latin. Someone who had once taken Latin was tracked down, and asked to translate. The translation was something like, "Unto the son is born a brother". When the original programmer was tracked down, he was embarrassed. "But that condition was never supposed to arrive. He had some kind of complicated data structure, where each element could have children and siblings. Except the element at the apex of the tree was supposed to be a special case -- no siblings.
But since it was never supposed to happen the original programmer didn't bother to put a meaningful error message.
Back with good old version 7, make gave error messages like:
make: stop. don't know how to make foo!
if you had typed "make foo" and there was no makefile, or no rule for foo in the makefile.
When computer naive people (remember them) would ask what computers could do, it was fun to have them sit down and type:
make love
Which would, of course, result in:
make: stop. don't know how to make love!
"make war" was another good one.
Isaac Asimove wrote one of his science essays on this. I remember reading it as a kid. I remember he calculated that a winged horse, like Pegasus, would need a wingspan of 200 feet -- just like the Gossamer Condor.
One of the Alaskans compared the mystery bird to a Twin Otter .
The Otter's wingspan is 65 feet for crying out loud.Thanks for the info. I found some additional information . There was some talk of using this gold-plated mini-shuttle as the rescue vehicle. Then this design was being worked on. Even though its budget was, as Lars pointed out, cut for 2002, they still test launched it as recently as December 2001. This link has some info on the use of the Soyuz as the rescue vehicle.
I hadn't realized that US budget decisions had cut the ISS back to a skeleton crew. Here is a press release from a US Senator commenting on a recently released independent review of the Space Station's Science programs.
Buran, the Soviet shuttle, has been discussed here on slashdot in the past. I spent most of an afternoon following some links other slashdotters had provided to details of Buran's design.
I found it fascinating. They do look similar. But there were some important differences, under the skin.
One of the web-pages discussed the similarity in appearance of Buran and the American shuttles. It said that Soviet engineers had considered a number of hull designs, with differing appearances. The other hulls looked, on paper, as if they would be just as successful as the American hull design. IIRC the only advantage of the American hull design was that it was a proven design.
The American shuttle uses strap on boosters fueled with solid fuel. Buran's boosters are liquid fueled, and it could strap on three of them. Consequently, it had a much larger lift capacity than the American shuttle.
Buran's crew, at least four of them, were protected by ejection seats.
It has been a year or two since I read these pages. I may not remember them correctly. But wouldn't Buran's liquid fueled boosters be innately safer than the American shuttle. Solid fueled rockets can't be shut down. If the challenger had liquid fueled boosters, would they have been able to shut down the booster, and have a greater chance of survival? Liquid fueled boosters wouldn't have had the dangerous "O ring" feature.
I asked this elsewhere. How many shuttle missions leave with a full payload? I believe that Hubble filled the cargo bay, as did the various ISS modules, and the European Spacelab. But doesn't that leave dozens of missions with partially loaded cargo bays?
Yeah. The ISS has a Soyuz docked to it, to serve as a lifeboat, if the ISS suffers a disastrous failure. The Soyuz can fit three spacesuits, so when the shuttle leaves they only leave three scientists aboard the shuttle at any one time.
Well, the Soyuz isn't left there permanently. They loft a new one every six months or so. So, if the Russians pack up their Space program either the ISS inhabitants have to get left there with no lifeboat, or a substitute has to be designed.
How difficult would designing a return module be? It wouldn't have to be as robust or sophisticated as a Soyuz, Apollo or Gemini, if its sole purpose was to serve as a lifeboat. It could be brought to the ISS by a shuttle, so it wouldn't need to control the one shot rocket that launched it. And, it wouldn't require the endurance of an Apollo or Soyuz. Its mission would last less than an hour or two. It would only have to endure long enough to bring the ISS researchers back to Earth.
I read, a long time ago, that the US shuttle's design incorporates features to serve the USAF, or reasonable equivalent. The story, as I read it, was that NASA didn't think it could get the funding to build the shuttle if it didn't have allies inside the Beltway. Elements in the Defense department agreed to endorse the shuttle, provided they got input into its design. The large size of the shuttle was given as one of those compromises. The suggestion was that if NASA had been allowed to build a shuttle without design compromises, it would have been more successful.
I'd welcome knowledgeable comments on this story. Sorry, I can't remember where I read it.
As it turned out, the US military doesn't use the shuttle, do they? Don't they use the old one-shot rockets?
Why does the shuttle have to be so big? Okay, Hubble, and the various ISS modules more or less fill the shuttle bay. But there have been something like 100 shuttle missions so far, how many of those missions had payloads that fully filled the cargo bay? They could all have been launched with big one-shot rockets, couldn't they? The 197?s Skylab was launched by a surplus Saturn V wasn't it?
The Hubble repair missions could have been mounted from a more modestly sized shuttle, couldn't they?
I read, something interesting back during the first years of Hubble's deployment, back before its optics were corrected, and everything was out of focus. NASA cut corners. They tested all the pieces separately, on the ground. But they didn't test the fully assembled telescope on the ground. I read that they considered doing so, but it required the construstion of a test jig. The test jig would have been expensive, and the decision was made to gamble.
The story was that the US already possessed a test jig suitable for testing large space telescopes. But NASA couldn't use it, because it was top secret, because it was used to test the large telescopes of top secret spy satellites, which were focussed on the Earth.
Can anyone debunk this story? If true, those satellites must have been launched by one-shot rockets.