...for long-term survival of our species on Earth is ~1 billion years. This is roughly when increased thermal output of the sun (in its prepetual battle to hold itself up against its own gravitational pressure) will cause temperatures on Earth to rise to the point that the oceans start to boil away.
of course, by then, the machines will have taken over, so the issue of human survival will become moot.
"Oh well, just time for a quick bath then. Pass the soap could you someone." -Douglas Adams
So far as I can see, out of the top 3 or 4 solutions, his was by far the most likely to work well. Now, that might be partly luck, but given the technical sophistication, and the fact that he actually got his strategy to work, and work well under such tight time pressures; I don't think it was luck at all.
Actually it sounded more like SELinux to me. Isn't that what SELinux is all about? Partitioning the system and protecting one application from another?
Actually, it's not 9 orders of magnitude that's the problem; that's only why it would cost umpteen billion dollars. We can probably make a few billion 3cm lengths readily enough.
The only remotely funny thing here is that the cable, if it took a year to go around in it's orbit would wrap itself 364.25* times around the earth. Trouble is, it doesn't, because the guy who wrote the piece put the word 'year' where he meant to say 'day'. And I got that. But I also knew that 36000km is geosynchronous orbit radius... so even the dumbest person knows that the guy screwed up. Oh wait...
* - see if you can work out why it's not 365.25 (why aren't I holding my breath, love the caps by the way, tasteful).
No, the batteries would be much too heavy. Not even fuel cells. Surprisingly, nuclear might work (you're going to need lots of shielding anyway for the passengers- the elevator goes right through the Van Allen radiation belts), but that would be an unpopular option I would expect.
Incidentally, you don't need to recharge before you descend, you can just run a generator off the cable as you fall. It takes lots and lots of energy to push you up the elevator cable, so on the way down you get it back again and so you've got more energy than you know what to do with. Your brakes are going to be hot.
It might be possible, but no known organism builds them. It's probably a very energetically intensive process, so any organism that stumbled across the right process to build it probably wouldn't keep the genes to do that; since other materials are cheaper and do nearly as well (spider silk is probably better for catching flies than nanotubes would be, since it's more stretchy.)
Just because it's made of carbon doesn't make it easy to build. I don't know of any organism that makes diamond either (although if I did, I probably wouldn't tell anyone anyway:-) ).
If you read that article really carefully you'll note that they said it was stronger than steel, but tougher than any material. Steel isn't massively strong (Kevlar is stronger), however toughness is journalistic speak for 'how much energy can it absorb before it snaps'. That's cool, but for an elevator you need tensile strength, not energy absorption; you're not catching flies with it:-)
(And don't even think about catching space junk- it's going way to fast for that!)
Um, no. Only the bit above geosynchronous orbit pulls away from the earth, the rest is hanging down. So if you break the tether at or below geosynchronous then the lower part falls, the upper part heads off towards the asteroid belt, depending on where the break is (I'm not actually making that bit up- if you lose the very tip it could even reach Jupiter!). The lower part just falls. However the section a bit above halfway can end up in a stable elliptical orbit; the rest will reenter.
The cable is only epoxied together, so anything past 100 km or so above the earth would fall apart into fibers during reentry (you'd probably blow it up into sections to help it melt correctly). Nobody knows what effect breathing these fibers in would have.
Incidentally everyone envisages the cable as being made of metal- it actually would weigh on order 1kg per kilometer, so it's not going to hurt you (although I wouldn't want to motorcycle fast at a section for obvious reasons.)
Actually they are planning on using wireless to power the elevator (probably laser power)- wires would be far too heavy; and you need a lot of energy to climb that high.
So far as I know the data connection technology for the car has not been speced yet, so I don't know how they intend to get Slashdot:-)
The state of the art is not quite strong enough or long enough.
Quote from the article:
"Until some of the basic science concerning how to connect nanotubes together and transfer load between them in a composite is understood it will remain elusive, but a lot of progress is being made."
Basically, the state of the art with carbon nanotubes is that you can build them a few centimeters long, of almost/just about the right strength (72 Gpa); but nobody has made or can make a rope even 1 foot long with the right strength (ideally 130 GPa including a 50% safety factor).
State of the art carbon nanotube ropes are down under 3GPa (less than Kevlar strength). To oversimplify the problem nanotubes are very slippery and hard to join with any strength. Splicing rope out of threads traditionally loses 20% of the strength, but nanotubes are too slippery, and not strong enough anyway for that right now.
Still, enormous progress has been made; and it looks surprisingly promising; but it's impossible right now.
Still, it's probably a good idea anyway- a lot of viruses and worms rely on users doing silly things.
The classic example is urban legends, these entirely rely on the misbehaviour of users- I've multiple times received emails warning me about LSD stickers going around that look like superman, about microsoft sending money to anyone that replied to an email etc. etc. These get sent by the hapless orginator who thinks they are doing the right thing, and often are sent to a huge distribution list.
The Microsoft one went around where I used to work and caused an email storm, where several hundred people all asked to be removed from the email distribution list. Trouble was, there was no distribution list, it was just a Cc'd email. This went on for several days with people calling each other names, and replying to everyone each time. It was ghastly; and the email servers were taking a severe beating with several hundred emails each being forwarded to several hundred destinations. And the whole thing was a hoax that anyone with google could check in 30 seconds flat.
This kind of thing can be mostly avoided by training people with access to email.
Whilst this is true; in practice it will look better than that- the human visual system is good at combining two slightly fuzzy images and coming up with apparently sharper images. In other words, even though the resolution each eye sees is halved, you have two different sets of halved resolution so you will almost get the full resolution back.
The big problem comes if the software doesn't antialias- then hard edges will be seen with one eye and not the other, and you will get headaches and stuff. Still, the human brain is fairly use to visual differences between the eyes- reflections of sunlight can often be seen with one eye and not the other due to the angles involved.
So the trust capacity of the shuttle is onpar with Saturn, so why do you need a Saturn!?!?!!?
Sure, you can design a new vehicle around the SSMEs but it's gonna cost billions.
But the engines aren't directly comparable. The F-1 engines are a fraction of the price of the SSMEs. The thrust:weight ratio of the F-1 engines are much higher than the SSMEs, so you lose payload. The density of the fuel of the F-1 is several times higher; so the fuel tank you would need is much bigger for the SSMEs. Now, I'm absolutely not saying it can't be done (indeed architectures to do this do exist), but you can't simply compare the thrust!
The shuttles engines are a decendant from Saturn.
Kinda, sorta, not exactly. The F-1 and the SSMEs aren't directly related.
Incidentally, your thrust figures are way off- together the SRBs provide 6.6 million pounds thrust, the SSMEs together are only 1.2 million pounds thrust.
As a rule of thumb the takeoff thrust of a rocket is about 1.5x the takeoff weight of the rocket and the payload of a rocket is about 1-2% of the takeoff weight. Saturn V has several time higher payload, so several times higher takeoff thrust.
Re:The Russians figured this one out years ago ...
on
The Return of Apollo?
·
· Score: 1
Yes. I feel similarly. However niggling problems can eventually add up to a death.
At the end of the day, the only figure I look at is the death rate; everything else is supposition.
For example, the Shuttle hasn't had any really nasty launch pad fires. But Soyuz has. Is that because NASA are more careful because they don't have an emergency ejection system? Maybe...
Re:The Russians figured this one out years ago ...
on
The Return of Apollo?
·
· Score: 2, Insightful
What's your point? Up until recently the Shuttle had gone 18 years without a fatality. It just takes one to reset the counter, and the Russians keep banging the Soyuz' around.
That IS my point. That's what 'not statistically significant means'. Please try to keep up Mr Anonymous:-)
To be fair, though, they haven't been as creative in finding uses for their spacecraft.
But I don't agree with this point in the slightest. The Ruskies have actually launched paying space tourists, they've actually turned a profit on that third seat, but I don't see the Shuttle doing that; ever. It's all a big screw up on NASA's part really.
The Space Shuttle would be a good case study for why the federal government is not able to take on these sorts of projects. The politics and bureaucracy destroy any optimism of the original plans.
Not really- they just didn't have enough money at the time to do it properly. Of course nobody else did either...
While it might be a bit scary at first, privatization is the only practical route to space from now on.
Yes, I think so.
Now if we could only convince them to stay out of matters of public schools,
No. A good education for the population, mostly or completely independent of wealth is essential for any industrial country to have a healthy economy.
health care,
No. Within reason, a healthy population is essential for a healthy economy. Anything that significantly increases the chances of bad health is a bad thing.
taxation....
Now you're trolling:-)
Re:The Russians figured this one out years ago ...
on
The Return of Apollo?
·
· Score: 2, Informative
Overall, the safety record of Soyuz is just fractionally better than the Shuttle, but it's not statistically significant.
However, as noted, the Soyuz has not had a failure in over 20 years, and the current design has had no fatalities in at all.
However, there have been some injuries during landing; sooner or later a fatality is not unreasonable.
I don't see much to choose right now, although there are theoretical reasons for thinking that Soyuz could be somewhat safer.
I refuse to believe that the best way to get into space is to fill a monstrous tube with combustibles and light it all up, just to get a few tons of gear in orbit.
A few tonnes?
Saturn V could lift the best part of 100 tonnes into orbit. It could have lifted the whole ISS in 2-3 launches, pretty much. (Skylab was huge compared to the ISS, and was at a much higher altitude).
By way of contrast, the Shuttle has only just got up to 30 tonnes, and the Shuttle is more expensive per tonne; and can't achieve the same altitude, and certainly isn't capable of lunar missions.
So what's the point of the Shuttle anyway? Because it's partly reusable so therefore it's cheaper isn't it? Umm, actually...
I'm not sure I understand why VoIP is so different from traditional phone calls.
It's a question of costs, degree and scale. The cost of bandwidth is dropping exponentially anyway, and going from conventional telephony to VOIP drops the costs by atleast a factor of 4 (due to compression) further. Essentially, telephony traffic is rapidly becoming not worth taxing.
What is the difference? A matter of what the encoder/decoders look like?
Largely. The point with VOIP is that you can install good compression at the endpoints- compression technology has made big strides in the last few decades, also the voice path needs only be open in one direction at a time (you're not blocked from talking by VOIP, but most of the time only one person talks and the compression compresses the other end down to nothing). This means that VOIP uses far less resources.
In fact, telecommunications bandwidth became predominately data a few years ago- the proportion of voice is shrinking away; and going to VOIP makes this happen much more so.
(Or for that matter, why email and AIM are not subject to taxation too, since they also travel over the same telco system, but even mentioning this greatly increases my troll-likelihood.)
You're wrong they are- email (and AIM in a different way) are already subject to taxation in most cases- you're paying for your bandwidth and the (very small) costs of, say, email comes out of your bandwidth carges; which are usually taxed anyway (atleast I pay tax on it here).
Yes, but F4 is smaller than Concorde, so produces less sonic boom than Concorde, also, Concorde goes supersonic at higher altitude, so produces less sonic boom because of that. So it's hard to compare.
Supersonic vehicles actually generate two booms- one for the nose and one from the tail- that's why this has the nose glove and the modified tail.
Incidentally, the size of the boom is related to the size of the aircraft, military planes are much smaller and hence give much less problems.
Interestingly, Concorde's nose is sharp- this is aerodynamically efficient, but generates bad sonic booms- it would be much better to use a rounded nose from that respect. Detailed changes to the tail section (other than the ones shown here) can also greatly reduce the shockwave. If you've seen Thunderbirds, some of the airliners shown there are strongly reminiscent of the kinds of shapes that probably help out, (strangely enough, that's probably because they got fairly good advice when designing their models.)
I think that the vehicle shown in the photo has a compromise nose shape- it's sharp on top to give better aerodynamics, but rounded underneath to project a weaker sonic boom downwards. Atleast that's my take on what they've done- IANAA. (I Am Not An Aerodynamicist).
Slashdot Mirror
of course, by then, the machines will have taken over, so the issue of human survival will become moot.
"Oh well, just time for a quick bath then. Pass the soap could you someone." -Douglas Adams
So far as I can see, out of the top 3 or 4 solutions, his was by far the most likely to work well. Now, that might be partly luck, but given the technical sophistication, and the fact that he actually got his strategy to work, and work well under such tight time pressures; I don't think it was luck at all.
Actually it sounded more like SELinux to me. Isn't that what SELinux is all about? Partitioning the system and protecting one application from another?
No, it's just the splicing problem.
* - see if you can work out why it's not 365.25 (why aren't I holding my breath, love the caps by the way, tasteful).
Incidentally, you don't need to recharge before you descend, you can just run a generator off the cable as you fall. It takes lots and lots of energy to push you up the elevator cable, so on the way down you get it back again and so you've got more energy than you know what to do with. Your brakes are going to be hot.
Just because it's made of carbon doesn't make it easy to build. I don't know of any organism that makes diamond either (although if I did, I probably wouldn't tell anyone anyway :-) ).
That makes IT SO FUNNY!
If you read that article really carefully you'll note that they said it was stronger than steel, but tougher than any material. Steel isn't massively strong (Kevlar is stronger), however toughness is journalistic speak for 'how much energy can it absorb before it snaps'. That's cool, but for an elevator you need tensile strength, not energy absorption; you're not catching flies with it :-)
(And don't even think about catching space junk- it's going way to fast for that!)
The cable is only epoxied together, so anything past 100 km or so above the earth would fall apart into fibers during reentry (you'd probably blow it up into sections to help it melt correctly). Nobody knows what effect breathing these fibers in would have.
Incidentally everyone envisages the cable as being made of metal- it actually would weigh on order 1kg per kilometer, so it's not going to hurt you (although I wouldn't want to motorcycle fast at a section for obvious reasons.)
So far as I know the data connection technology for the car has not been speced yet, so I don't know how they intend to get Slashdot :-)
Yeah it takes one day to complete a full orbit at 36000km! That's the whole point! :-)
Quote from the article:
"Until some of the basic science concerning how to connect nanotubes together and transfer load between them in a composite is understood it will remain elusive, but a lot of progress is being made."
Basically, the state of the art with carbon nanotubes is that you can build them a few centimeters long, of almost/just about the right strength (72 Gpa); but nobody has made or can make a rope even 1 foot long with the right strength (ideally 130 GPa including a 50% safety factor).
State of the art carbon nanotube ropes are down under 3GPa (less than Kevlar strength). To oversimplify the problem nanotubes are very slippery and hard to join with any strength. Splicing rope out of threads traditionally loses 20% of the strength, but nanotubes are too slippery, and not strong enough anyway for that right now.
Still, enormous progress has been made; and it looks surprisingly promising; but it's impossible right now.
The classic example is urban legends, these entirely rely on the misbehaviour of users- I've multiple times received emails warning me about LSD stickers going around that look like superman, about microsoft sending money to anyone that replied to an email etc. etc. These get sent by the hapless orginator who thinks they are doing the right thing, and often are sent to a huge distribution list.
The Microsoft one went around where I used to work and caused an email storm, where several hundred people all asked to be removed from the email distribution list. Trouble was, there was no distribution list, it was just a Cc'd email. This went on for several days with people calling each other names, and replying to everyone each time. It was ghastly; and the email servers were taking a severe beating with several hundred emails each being forwarded to several hundred destinations. And the whole thing was a hoax that anyone with google could check in 30 seconds flat.
This kind of thing can be mostly avoided by training people with access to email.
The big problem comes if the software doesn't antialias- then hard edges will be seen with one eye and not the other, and you will get headaches and stuff. Still, the human brain is fairly use to visual differences between the eyes- reflections of sunlight can often be seen with one eye and not the other due to the angles involved.
Sure, you can design a new vehicle around the SSMEs but it's gonna cost billions.
But the engines aren't directly comparable. The F-1 engines are a fraction of the price of the SSMEs. The thrust:weight ratio of the F-1 engines are much higher than the SSMEs, so you lose payload. The density of the fuel of the F-1 is several times higher; so the fuel tank you would need is much bigger for the SSMEs. Now, I'm absolutely not saying it can't be done (indeed architectures to do this do exist), but you can't simply compare the thrust!
The shuttles engines are a decendant from Saturn.
Kinda, sorta, not exactly. The F-1 and the SSMEs aren't directly related.
Incidentally, your thrust figures are way off- together the SRBs provide 6.6 million pounds thrust, the SSMEs together are only 1.2 million pounds thrust.
As a rule of thumb the takeoff thrust of a rocket is about 1.5x the takeoff weight of the rocket and the payload of a rocket is about 1-2% of the takeoff weight. Saturn V has several time higher payload, so several times higher takeoff thrust.
At the end of the day, the only figure I look at is the death rate; everything else is supposition.
For example, the Shuttle hasn't had any really nasty launch pad fires. But Soyuz has. Is that because NASA are more careful because they don't have an emergency ejection system? Maybe...
That IS my point. That's what 'not statistically significant means'. Please try to keep up Mr Anonymous :-)
To be fair, though, they haven't been as creative in finding uses for their spacecraft.
But I don't agree with this point in the slightest. The Ruskies have actually launched paying space tourists, they've actually turned a profit on that third seat, but I don't see the Shuttle doing that; ever. It's all a big screw up on NASA's part really.
Not really- they just didn't have enough money at the time to do it properly. Of course nobody else did either...
While it might be a bit scary at first, privatization is the only practical route to space from now on.
Yes, I think so.
Now if we could only convince them to stay out of matters of public schools,
No. A good education for the population, mostly or completely independent of wealth is essential for any industrial country to have a healthy economy.
health care,
No. Within reason, a healthy population is essential for a healthy economy. Anything that significantly increases the chances of bad health is a bad thing.
taxation....
Now you're trolling :-)
However, as noted, the Soyuz has not had a failure in over 20 years, and the current design has had no fatalities in at all.
However, there have been some injuries during landing; sooner or later a fatality is not unreasonable.
I don't see much to choose right now, although there are theoretical reasons for thinking that Soyuz could be somewhat safer.
A few tonnes?
Saturn V could lift the best part of 100 tonnes into orbit. It could have lifted the whole ISS in 2-3 launches, pretty much. (Skylab was huge compared to the ISS, and was at a much higher altitude).
By way of contrast, the Shuttle has only just got up to 30 tonnes, and the Shuttle is more expensive per tonne; and can't achieve the same altitude, and certainly isn't capable of lunar missions.
So what's the point of the Shuttle anyway? Because it's partly reusable so therefore it's cheaper isn't it? Umm, actually...
It's a question of costs, degree and scale. The cost of bandwidth is dropping exponentially anyway, and going from conventional telephony to VOIP drops the costs by atleast a factor of 4 (due to compression) further. Essentially, telephony traffic is rapidly becoming not worth taxing.
What is the difference? A matter of what the encoder/decoders look like?
Largely. The point with VOIP is that you can install good compression at the endpoints- compression technology has made big strides in the last few decades, also the voice path needs only be open in one direction at a time (you're not blocked from talking by VOIP, but most of the time only one person talks and the compression compresses the other end down to nothing). This means that VOIP uses far less resources.
In fact, telecommunications bandwidth became predominately data a few years ago- the proportion of voice is shrinking away; and going to VOIP makes this happen much more so.
(Or for that matter, why email and AIM are not subject to taxation too, since they also travel over the same telco system, but even mentioning this greatly increases my troll-likelihood.)
You're wrong they are- email (and AIM in a different way) are already subject to taxation in most cases- you're paying for your bandwidth and the (very small) costs of, say, email comes out of your bandwidth carges; which are usually taxed anyway (atleast I pay tax on it here).
It's only 2/3 of the altitude that Concorde cruises at.
Yes, but F4 is smaller than Concorde, so produces less sonic boom than Concorde, also, Concorde goes supersonic at higher altitude, so produces less sonic boom because of that. So it's hard to compare.
Supersonic vehicles actually generate two booms- one for the nose and one from the tail- that's why this has the nose glove and the modified tail.
Incidentally, the size of the boom is related to the size of the aircraft, military planes are much smaller and hence give much less problems.
Interestingly, Concorde's nose is sharp- this is aerodynamically efficient, but generates bad sonic booms- it would be much better to use a rounded nose from that respect. Detailed changes to the tail section (other than the ones shown here) can also greatly reduce the shockwave. If you've seen Thunderbirds, some of the airliners shown there are strongly reminiscent of the kinds of shapes that probably help out, (strangely enough, that's probably because they got fairly good advice when designing their models.)
I think that the vehicle shown in the photo has a compromise nose shape- it's sharp on top to give better aerodynamics, but rounded underneath to project a weaker sonic boom downwards. Atleast that's my take on what they've done- IANAA. (I Am Not An Aerodynamicist).