And tossing your heatshield after each flight is not economical at all.
I have to disagree... I have proprietary
pricing info from ablative heatshield vendors
about historical projects and ranges for new
ones which indicates that ablative TPS
systems should be dirt-cheap. First unit
prices under a megabuck cheap.
Low weight? Water? Are you nuts?
Water is heavy. Seriously.
And it has a huge heat capacity and
heat of vaporization. Seriously.
The technique is known as active
transpiration cooling, or just
transpiration cooling.
It has never been flown, but it has
better (lower) mass than other reusable
thermal protection system options
according to the engineering studies
done to date.
The space shuttle has a higher surface area compared to it's mass than an Apollo capsule too. Your rough calculations don't seem to take that into account.
That's because they don't have to. To a first order
approximation, thermal protection total heat capacity
for orbital re-entry is proportional to the vehicle
mass only, not the vehicle's surface area.
Denser vehicles with less surface area need
more thickness of heat shield per unit area.
It all comes out very nearly equal, with some
slight advantage for lower density, higher
surface area vehicles due to secondary effects.
Lower density, higher surface area vehicles will
decellerate more quickly at higher altitude.
Lifting re-entries, where you use hypersonic
lift due to wings or capsule shape to keep the
altitude higher and extend the decelleration
time, decellerate more slowly over longer
time but still at high altitude.
In all cases, the direct energy transfer into
the vehicle depends on the vehicle shape
(blunter is better, you want a detached shock
wave to keep the highest temperature gases
away from the vehicle) and its orbital
kinetic energy, which is dependent on its
mass and velocity. The energy dissipated in
ablative heatshields is fairly constant whether
it is a quick high intensity exposure or a longer
low intensity exposure.
The only difference with longer reentries is that
you have to worry more about heat soakthrough
on the back surface of the heatshield. Normally
the back surface is a lighter, low density
insulating foam, which is a small faction of
the total heatshield mass. For some designs
the whole heatshield is made of that material.
Depends on the conditions, etc.
I sent for a starter package on the America's Space Prize 2 months ago, and I never recieved a reply of any sort. I don't think it actually exists.
If you're serious, contact them again.
For their own reasons, they did early
announcements before the whole rules
and signup packages were ready.
However, as someone who contacted
them before they even officially
announced it, I can assure you that
they are responding to potential
competitors that they believe are
credible, and they are in the process
now of recontacting people and sending
out the full official info packets.
I only had to make two phone calls
on my side, and have received a number
of responses over the last month-plus,
including one yesterday.
Propellants: Lox/Kerosene Thrust(vac): 423,050 kgf. Thrust(vac): 4,152.00 kN. Isp: 338 sec. Isp (sea level): 311 sec. Burn time: 150 sec. Mass Engine: 5,393 kg. Diameter: 3.00 m. Length: 3.56 m. Chambers: 2. Chamber Pressure: 257.00 bar. Area Ratio: 36.87.Oxidizer to Fuel Ratio: 2.72. Country: Russia/USA. Status: Hardware. First Flight: 1999
wait.. isn't "cheap" one of your requirments? Are you saying that if you scrap that one you can build it for less?:)
No, he's saying that "reusable" is one of the
requirements, and if you scrap that one then
you can build it for less. And lighter, too.
The Space Shuttle tiles aren't lighter
than a good ablative heatshield would be.
The shuttles have about 18.5 metric tons of tiles
and thermal blankets and leading edge RCC
panels, out of a total gross weight of 104
metric tons (18%).
Apollo, which was
re-entering at a higher
velocity coming back from the moon, has a
thermal protection system weight of 850 kg
out of 5,800 kg total mass (15%).
The proposed British Multi Role Capsule
re-entering from low orbit had 666 kg of
thermal protection system mass, out of 6,200
kg total mass (11%).
His actual budget was a fraction of the
$1.5 billion he made on PayPal, not the whole amount.
There is no way that SpaceX would be profitable
selling rockets for $6 and $12 million each if he
spent $1.5 billion developing them.
That's part of the reason why normal space launch
rockets cost $40 to $250 million (or more...).
Good for him, but that doesn't mean that you know with any reasonable degree of certainty that the production environment is necessarily in a boot-clean-to-normal-operation configuration after a given change without actually doing the reboot.
It is nigh-on impractical to guarantee that there has been no deviation or differnence between preproduction / staging envrionment and the live production environment which would cause problems like that.
There are good reasons for manintenance windows and failover / loadbalanced systems. They let you test to be confident that you haven't busted something you don't realize (yet), before it bites you in the ass in production during the middle of a busy day...
So is this the fatal flaw of FOSS? Do folks like you and I fall into the trap of assuming just because it's easy for *us* to do what we do, others should find it easy too? Is this the one obstacle that, if overcome, FOSS could indeed rival others in the desktop market?
Dingdingdingdingding
We have a winner.
There's no reason to claim that all proprietary software has better UI than FOSS, nor that no FOSS has excellent normal user intuitive UIs. However, there is a huge gap between average UI experience in "popular" proprietary software and FOSS in general.
"normal people" don't want to be learning contorted UIs like geeks groove on. They want to be using functions, fast and as easily as possible. Software with less functions but which gets the user to them faster and more easily is superior in "normal users" eyes.
My spouse is both a longtime UNIX CLI and X user with some CS classes in college, and a graphic artist and designer. What she has to say about the quality of the FOSS graphics tools is unprintable. She's used Macs for graphics and layout consistently, and would probably be ok with Windows programs (whose UIs are now roughly tied with Mac) if the platform didn't suck so badly.
The sad part is that the User Interface ideas are things that can more or less be freely adopted from good commercial products into FOSS, if people cared about the problem...
but factory tires are usually good for up to 15,000 miles, if you're lucky.
Either that's the worst telegraphed sarcasm I have seen on/. in months, or you're chewing tires up like bubblegum. Where do you drive, Daytona and Indianapolis exclusively?
Try 40,000 miles to 50,000 miles. Most new tires come with warrantiesfor 40,000 miles or more.
There is a huge difference between using radiothermal energy and a fission reactor, and even JIMO is only 1kW of power
According to a friend who is on the science and operations teams on lots of NASA probes and keeps a keen eye on upcoming projects,
the JIMO reactor specification is...
roughly, line by line...
identical to the 1980s/early 90s
SP-100 reactor, which is 100 kilowatts.
What you describe as a down-fall is a technical problem which can surely be solved.
Oh?
Why are you sure it can be solved?
What do you know about battery engineering that thousands of professional scientists and engineers around the world, most of whom are as smart or smarter than you are and who have a hell of a lot more specific useful training in electrical physics and battery chemistry, don't know?
It's not just Wave a magic battery fairy wand.
They're working hard on these problems, because electric cars are just one of many many things that could use really long life, rugged battery systems with high density.
As has been pointed out more rudely by dozens of earlier responders, nothing in the initial question argues for needing root.
The job role of Webmaster varies widely, from people whose responsibility it is to make sure that the links work and just about only that, to people who own the applications and content management, to people who build the server from bottom up including OS install and web apps and programming and HTML code and UI specification.
The latter person owns the box. Most of the people short of that level don't need root. If you're maintaining the applications environment and need to install new versions of Apache, PostgresSQL, Tomcat or whatever, then you and the sysadmin need to come to an agreement on how that gets done.
If you need to restart Apache, that's what Sudo is for.
In any case, your job, rather than escalating the situation, is understanding and communicating the situation. If you need root, you need to understand and articulate why you need root. If you can't justify why you need it, you shouldn't be trying to go over his or her head. If you can make the case clearly and they still won't let you have it, then you can escalate.
By adding a printer, you're conceding that the electronic voting machine may not innately be able to provide complete confidence in the result.
I think you need to acknowledge that you have a tougher standard you want to see followed than any other security-conscious electronic voting expert.
You are entitled to your opinion, however, if you can't convince some of the rest of us that it's important, you are going to have to live with not getting it.
I think that your criteria for e-voting security are significantly higher than society's base security requirements for other voting systems. It is not possible or intended to make vote fraud impossible. The systems are designed to make it hard enough that significant amounts of it are detectable by normal auditing procedures. E-voting machines with paper trail printers clearly reach that threshold, in my opinion and the consensus opinion of experts.
If you read your own link, you'll notice the Indian's powered down their own NPP, just 8 months after it started to use just part of its fuel for their bomb, so they were using "fresh" fuel, and apparently mixing it with "pure" plutoniom they already had. Because of this, I don't think you've proven your point.
The Indians powered down their NPP and then reused the fuel, but by then it had been irradiated moderately extensively. And it was not, as far as I can tell, reprocessed before it was used in the bomb.
But the arguments that RGPU weapons are impractical have been thoroughly discredited
That depends on your definition of RGPU. If we're talking, and this was mentioned earlier in the thread, about Integral Fast Reactors, the answer is no. The fuel from this kind of reactor, is exceedingly difficult to use for weapons. So difficult to use in fact, that any country capable of doing it, is almost certainly technically capable of making even better nuclear bombs the conventional way like everyone else.
All of the plutonium isotopes are fissionable.
Even pure Pu-240 or Pu-242 could be built into a bomb. A really, really difficult to engineer bomb, but a bomb nonetheless.
And any reactor output of plutonium can be processed with the types of equipment used to enrich Uranium to get modern weapons grade Pu, if you want. With hundreds of times less separation effort.
There's a common delusion, pushed by IFR fans among others, that there is a "safe" Plutonium output type which will not be a practical proliferation concern. You find it throughout IFR literature. It's bogus. All of the reactor fuel cycle isotopes are potential bomb materials. Separating out the Pu-239 from even the IFR output is an easy task in nuclear terms.
Those factors make it so difficult to make bombs out of recovered PWR plutonium that not one proliferator, not India or Pakistan or Iraq or Iran or North Korea, has even tried to make a bomb that way.
This is grossly unsupported by proper engineering analysis and history. India's first bomb used reactor material, which had even been used as plutonium in a fast fission plutonium fueled research reactor. Many other nations have fired test bombs using RGPU.
There is no dispute that it's harder to use RGPU than Weapons Grade, or U-233. But the arguments that RGPU weapons are impractical have been thoroughly discredited. Harder is not impractical. More dangerous to handle is not impractical.
The estimates are that we'd have a ~100 year supply of Uranium if all power was switched to nuclear power today. This figure does not take reprocessing and non-uranium fission into account.
That's without going to lower yield Uranium ores or breeder reactor usage. Either of those will extend it by a factor of ten or more, more than a factor of 100 if you do both, and if you include oceanic Uranium then the total lifetime goes out towards a billion years.
Inflaming the Linuxheads with trollish tradepress articles is nothing new for slashdot -- remember Bob 'Open Sores Movement' Metcalf?
Bob Metcalfe, though he had a number of contrarian opinions that I disagree with, was in no way misreporting or lying about sources or court filings.
There is a tendency in open source circles, and on/. in particular, to assume that anyone who disagrees with the open source dogma is some sort of malign entity with secret agendas.
Bob, and a number of other people, had and have honest disgareements with open source among other things.
Treating this as a religious war... in which no dissenting opinion can be held honestly and with integrity, and where all dissent must be supressed or ridiculed... is just wrong. Open source is ultimately about economic and social value: if it works better (for users / consumers / programmers / IT organizations / businesses) it will be used more and it will win on its merits. I think that it's clearly winning on its merits there now.
The motiviation here is that everyone in the press (including/.) wants to get a little more mileage out of this story.
I think that getting a bunch of people aware that the author is writing apparently false material, and exposing that SCO are possibly feeding false stories to the media (can you say illegal stock manipulation and SEC investigation?) is an important thing to do.
If nothing else, I want to know that I can't trust the next thing she writes, and I want to know that I need to not trust the next magazine/newspaper/website that publishes the next thing she writes.
It may be difficult to get the word out about misinformation in journalism without perversely giving some protmotions to the particular story, but it's important for people to know when news sources go bad. Asking for a perfect way to publicize the bad without unfortunately boosting it a bit temporarily is asking too much. Real life is about compromises.
This wasn't a launch to orbit. It was a large suborbital rocket, just going up and down again.
The US calls these sounding rockets.
Hopefully Brazil will get its satellite launch program back up and running. It was severely damaged when one of the solid rocket motors ignited in a rocket being set up on the pad for launch, which destroyed the pad and killed the technicians working to set it up.
Don't heros do something heroic other then just die in a large explosion?
Sure.
Having the guts and drive to survive the astronaut
selection program and then climb onto a stack
with a few thousand tons of solid rocket fuel
and liquid hydrogen and oxygen, with what's
likely a 1% or higher risk of death, certainly is
a fairly heroic set of circumstances.
"So, what was the point of creating a 128-bit filesystem?
Getting rid of file/drive size limitations for the foreseeable future?
Being able to fully address very large but sparse datasets.
There are plenty of applications for fully using 64 bits even if you don't have anywhere near 2^64 bytes of actual data on a system.
Not common, but there are uses.
Also, the point in thread below about drive sizes and the 15 year timeframe is valid. There exist thousand drive RAID arrays today. With the existing growth curve, if you exceed 2^64 bits in a thousand drives in 14-15 years, that's a reasonable long term planning horizon for things like major OS standards and capabilities. If you are doing a new major thing, planning for 15 year out capabilities isn't a bad idea.
Slashdot Mirror
It's all been downhill since Ygdgrasil Linux 1.0 in 1992, with the 5.25" boot floppies and all.
The technique is known as active transpiration cooling, or just transpiration cooling.
It has never been flown, but it has better (lower) mass than other reusable thermal protection system options according to the engineering studies done to date.
Lower density, higher surface area vehicles will decellerate more quickly at higher altitude. Lifting re-entries, where you use hypersonic lift due to wings or capsule shape to keep the altitude higher and extend the decelleration time, decellerate more slowly over longer time but still at high altitude.
In all cases, the direct energy transfer into the vehicle depends on the vehicle shape (blunter is better, you want a detached shock wave to keep the highest temperature gases away from the vehicle) and its orbital kinetic energy, which is dependent on its mass and velocity. The energy dissipated in ablative heatshields is fairly constant whether it is a quick high intensity exposure or a longer low intensity exposure.
The only difference with longer reentries is that you have to worry more about heat soakthrough on the back surface of the heatshield. Normally the back surface is a lighter, low density insulating foam, which is a small faction of the total heatshield mass. For some designs the whole heatshield is made of that material. Depends on the conditions, etc.
For their own reasons, they did early announcements before the whole rules and signup packages were ready.
However, as someone who contacted them before they even officially announced it, I can assure you that they are responding to potential competitors that they believe are credible, and they are in the process now of recontacting people and sending out the full official info packets.
I only had to make two phone calls on my side, and have received a number of responses over the last month-plus, including one yesterday.
Such as 10 times smaller?
RD-180:
RD-180 info at astronautix.com
Merlin:
SpaceX page on Merlin via flash link
The Space Shuttle tiles aren't lighter than a good ablative heatshield would be. The shuttles have about 18.5 metric tons of tiles and thermal blankets and leading edge RCC panels, out of a total gross weight of 104 metric tons (18%).
Apollo, which was re-entering at a higher velocity coming back from the moon, has a thermal protection system weight of 850 kg out of 5,800 kg total mass (15%).
The proposed British Multi Role Capsule re-entering from low orbit had 666 kg of thermal protection system mass, out of 6,200 kg total mass (11%).
There is no way that SpaceX would be profitable selling rockets for $6 and $12 million each if he spent $1.5 billion developing them. That's part of the reason why normal space launch rockets cost $40 to $250 million (or more...).
It's not even the right name for the company.
See www.spacex.com
Someone's got an itchy E key.
It is nigh-on impractical to guarantee that there has been no deviation or differnence between preproduction / staging envrionment and the live production environment which would cause problems like that.
There are good reasons for manintenance windows and failover / loadbalanced systems. They let you test to be confident that you haven't busted something you don't realize (yet), before it bites you in the ass in production during the middle of a busy day...
We have a winner.
There's no reason to claim that all proprietary software has better UI than FOSS, nor that no FOSS has excellent normal user intuitive UIs. However, there is a huge gap between average UI experience in "popular" proprietary software and FOSS in general.
"normal people" don't want to be learning contorted UIs like geeks groove on. They want to be using functions, fast and as easily as possible. Software with less functions but which gets the user to them faster and more easily is superior in "normal users" eyes.
My spouse is both a longtime UNIX CLI and X user with some CS classes in college, and a graphic artist and designer. What she has to say about the quality of the FOSS graphics tools is unprintable. She's used Macs for graphics and layout consistently, and would probably be ok with Windows programs (whose UIs are now roughly tied with Mac) if the platform didn't suck so badly.
The sad part is that the User Interface ideas are things that can more or less be freely adopted from good commercial products into FOSS, if people cared about the problem...
Try 40,000 miles to 50,000 miles. Most new tires come with warranties for 40,000 miles or more.
Oh?
Why are you sure it can be solved?
What do you know about battery engineering that thousands of professional scientists and engineers around the world, most of whom are as smart or smarter than you are and who have a hell of a lot more specific useful training in electrical physics and battery chemistry, don't know?
It's not just Wave a magic battery fairy wand. They're working hard on these problems, because electric cars are just one of many many things that could use really long life, rugged battery systems with high density.
So far it hasn't had easy answers.
The job role of Webmaster varies widely, from people whose responsibility it is to make sure that the links work and just about only that, to people who own the applications and content management, to people who build the server from bottom up including OS install and web apps and programming and HTML code and UI specification.
The latter person owns the box. Most of the people short of that level don't need root. If you're maintaining the applications environment and need to install new versions of Apache, PostgresSQL, Tomcat or whatever, then you and the sysadmin need to come to an agreement on how that gets done.
If you need to restart Apache, that's what Sudo is for.
In any case, your job, rather than escalating the situation, is understanding and communicating the situation. If you need root, you need to understand and articulate why you need root. If you can't justify why you need it, you shouldn't be trying to go over his or her head. If you can make the case clearly and they still won't let you have it, then you can escalate.
But understand first and explain second.
I think you need to acknowledge that you have a tougher standard you want to see followed than any other security-conscious electronic voting expert.
You are entitled to your opinion, however, if you can't convince some of the rest of us that it's important, you are going to have to live with not getting it.
I think that your criteria for e-voting security are significantly higher than society's base security requirements for other voting systems. It is not possible or intended to make vote fraud impossible. The systems are designed to make it hard enough that significant amounts of it are detectable by normal auditing procedures. E-voting machines with paper trail printers clearly reach that threshold, in my opinion and the consensus opinion of experts.
All of the plutonium isotopes are fissionable.
Even pure Pu-240 or Pu-242 could be built into a bomb. A really, really difficult to engineer bomb, but a bomb nonetheless.
And any reactor output of plutonium can be processed with the types of equipment used to enrich Uranium to get modern weapons grade Pu, if you want. With hundreds of times less separation effort.
There's a common delusion, pushed by IFR fans among others, that there is a "safe" Plutonium output type which will not be a practical proliferation concern. You find it throughout IFR literature. It's bogus. All of the reactor fuel cycle isotopes are potential bomb materials. Separating out the Pu-239 from even the IFR output is an easy task in nuclear terms.
This is grossly unsupported by proper engineering analysis and history. India's first bomb used reactor material, which had even been used as plutonium in a fast fission plutonium fueled research reactor. Many other nations have fired test bombs using RGPU.
There is no dispute that it's harder to use RGPU than Weapons Grade, or U-233. But the arguments that RGPU weapons are impractical have been thoroughly discredited. Harder is not impractical. More dangerous to handle is not impractical.
See:
Reactor Grade Plutonium's Explosive Properties by J Carson Mark.
India's Nuclear Weapons Program - Smiling Buddha: 1974 from the Nuclear Weapons Archive (Carey Sublette)
Nuclear Weapons FAQ Section 6.2: Fissionable Materials, 6.2.2.10 Reactor-Grade Plutonium from the Nuclear Weapons FAQ (Carey Sublette)
Nuclear Weapons FAQ Section 4.2: Fission Weapon Designs, 4.2.6.1 Clandestine Weapons, 4.2.6.1 Terrorist Bombs from the Nuclear Weapons FAQ (Carey Sublette)
That's without going to lower yield Uranium ores or breeder reactor usage. Either of those will extend it by a factor of ten or more, more than a factor of 100 if you do both, and if you include oceanic Uranium then the total lifetime goes out towards a billion years.
See for example:
John McCarthy's Sustainability page on nuclear power resources.
There is a tendency in open source circles, and on /. in particular, to assume that anyone who disagrees with the open source dogma is some sort of malign entity with secret agendas.
Bob, and a number of other people, had and have honest disgareements with open source among other things.
Treating this as a religious war... in which no dissenting opinion can be held honestly and with integrity, and where all dissent must be supressed or ridiculed... is just wrong. Open source is ultimately about economic and social value: if it works better (for users / consumers / programmers / IT organizations / businesses) it will be used more and it will win on its merits. I think that it's clearly winning on its merits there now.
I think that getting a bunch of people aware that the author is writing apparently false material, and exposing that SCO are possibly feeding false stories to the media (can you say illegal stock manipulation and SEC investigation?) is an important thing to do.If nothing else, I want to know that I can't trust the next thing she writes, and I want to know that I need to not trust the next magazine/newspaper/website that publishes the next thing she writes.
It may be difficult to get the word out about misinformation in journalism without perversely giving some protmotions to the particular story, but it's important for people to know when news sources go bad. Asking for a perfect way to publicize the bad without unfortunately boosting it a bit temporarily is asking too much. Real life is about compromises.
The US calls these sounding rockets.
Hopefully Brazil will get its satellite launch program back up and running. It was severely damaged when one of the solid rocket motors ignited in a rocket being set up on the pad for launch, which destroyed the pad and killed the technicians working to set it up.
Shoulda' just done what I did, and replaced the compiler with a spurious error message generating wrapper...
Compiler says 'Ack' from rec.humor.funny
Having the guts and drive to survive the astronaut selection program and then climb onto a stack with a few thousand tons of solid rocket fuel and liquid hydrogen and oxygen, with what's likely a 1% or higher risk of death, certainly is a fairly heroic set of circumstances.
There are plenty of applications for fully using 64 bits even if you don't have anywhere near 2^64 bytes of actual data on a system. Not common, but there are uses.
Also, the point in thread below about drive sizes and the 15 year timeframe is valid. There exist thousand drive RAID arrays today. With the existing growth curve, if you exceed 2^64 bits in a thousand drives in 14-15 years, that's a reasonable long term planning horizon for things like major OS standards and capabilities. If you are doing a new major thing, planning for 15 year out capabilities isn't a bad idea.