"A solid fuel rocket is like a firecracker - once you light it there is nothing you can do to control it in any way. Other systems have to be changed to compensate for that."
From what I'm given to understand, there *are* controls available to a solid fuel rocket. There is thrust vectoring, of course. But they can vary the side and shape of the burn channel, and they can vary the formulation of the fuel. This changes the performance characteristics of the propellant, giving you something like a throttle.
The big difference is this has to be decided at manufacturing time. Obviously, liquid fuel rockets give you more flexibility in that the plan can be changed in-flight. However, I'm also told that the realities of flight dynamics mean there's a fairly narrow range of safe maneuvering options, beyond which the vehicle will breakup. And it isn't like you can just prematurely "turn off" a rocket and expect things to end well. So the reduced control that comes from a solid fuel rocket design is apparently not as big a problem as one might expect at first glance.
Now, I'm not arguing that solid rockets are the best possible option. From what I understand, they just have cost and reliability on their side. And the cost claim has been challenged in a fair fashion elsewhere in this subthread, so I'm even less sure about that now.
"Solid rockets have significantly cheaper R&D costs. The per flight costs are not better. Especially when you are comparing versus a reusable liquid fueled stage."
Again, please provide a reference. A solid rocket is basically propellant in a tube. (Okay, there will be some sophistication at the nozzle for flight control.) A liquid fuel rocket engine is an incredible complex of pipes, pumps, valves, controls, and injectors. They need sophisticated fuel generation and storage facilities.
In particular, I've seen the SSMEs called the most expensive rocket engines ever to fly. A single engine unit costs more than an entire Delta launch. They can only be used a limited number of times, and they have to be rebrurb'ed after every launch.
"Falcon 9 is an all-liquid rocket, meaning it isn't prone to catastrophic solid propellant explosions like the Ares I is."
Right, it's "prone" to catastrophic liquid propellant explosions instead.
Historically, solid rockets are more reliable when it comes to them not exploding. They're much simpler designs, and much more robust. Heck, parts of the SRBs on STS-51-L (the one that killed Challenger) survived the initial explosion and kept flying. They had to detonate the range safety charges to stop them. If it hadn't been for the giant liquid fuel tank next to the SRBs, the O-ring leak wouldn't have been a problem. (Obviously, since there was a giant liquid fuel tank, that's a huge problem, but the point of discussion is the reliability and robustness of solid rockets, not the STS as a whole.)
Solid rockets are cheaper, simpler, more robust, and have a higher thrust-to-weight ratio. But control options are limited. You can't vary thrust from plan, and once lit they will consume their entire fuel supply. No stop-and-restart.
Liquid rockets are more controllable, restartable, and have better propellant efficiency. But they are more costly, more complex, and more fragile. To quote a rocket scientist I was conversing with, "There are plenty of examples of liquid rockets going BOOM and everyone being surprised."
Now, I believe the mechanics of launch to orbit dictate that you pretty much need at least one liquid fuel stage. SpaceX reasons that you're better off using the same technology everywhere, to reduce overall design, manufacturing, and support costs. I suspect they are correct. If you have to build a good liquid rocket engine, you might as well use it everywhere. Using two different technologies means twice as many problems.
"once the moon landing was no longer politically potent, they killed them (at exactly the same time NASA started sending scientist rather then fighter pilots)."
In fairness, the Apollo "fighter pilot" astronauts are/were prolly smarter than you or I. Neil Armstrong obtained an aerospace engineering degree before he became a test pilot. Buzz Aldrin was an MIT PhD. Yah, they were stick jockeys, too, but they were the elite of that field. They weren't jarheads.
"Next to military gear, space gear is the perfect line of business. Much of it will either be blown up or sent to unrecoverable locations. This means that the customer will always be coming back for more."
For that matter, the military generally wants the stuff that isn't supposed to blow up to last forever.
Of course, lots of that is achieved through sustained maintenance, which is also good for business. But I have to deal with the "disposable" mentality in the commercial sector, and I'm not sure the military doesn't have the right idea there.
"No one tries 'efficient' because no one is motivated and it would actually interefere with their personal fiefdom building."
In fairness, that happens all the time in private companies, too. It's just less public because they're, ya know, private.
I'm not saying this to defend government so much as to also criticize private companies. They both suck.
If there's any conclusion I can reach, it's that large organizations of any type are the problem. When you scale up, you inevitably get longer lines of communications, a higher tolerance for mediocrity (you need more people than the cream of the crop can provide), the need for more formal procedures (to compensate for the first two), deeper pocket to fund fief building, and more places to hide it all.
I think Space-X wins because they're small, nimble, and fresh. And more power to them for it.
"... hoping for a repeat of the Saturn-V's 12/12 record..."
It's worth pointing out that 12 mission launches is not much data to draw on. And at least one Saturn V component blew up in a test flight, so it was not perfect, either.
I'm not saying the Saturn V wasn't an achievement, or that it wasn't a good design, just that we should beware of romantic illusions.
"Evem early in the game, the solid booster system was known to result in a cost increase of 60% per pound into orbit."
Can you provide a reference for that? I've been told by an actual rocket scientist that solid fuel rockets are significantly cheaper than liquid fuel rockets, especially for the boost phase, where thrust-to-weight matters more than propellant efficiency.
I've also seen inflation-adjusted figures for Saturn V vs STS, and the Saturn V was vastly more expensive. Now, they only flew about two dozen Saturn V's, so they never had a chance to develop economies of scale, but it's not like the STS is a huge win in that department either. The Saturn V also had a much greater total lift capacity, so this may be apples-to-oranges in the first place.
Certainly, liquid fuel rockets have a number of advantages, but I haven't seen anything to suggest cost is one of them.
(Note that I'm not saying the STS SRBs were an overall win. Good design theory won't save a badly run program. I just question the idea that's it's *because* they were solid rockets that costs were high.)
If the problem is that you're having trouble making things look the way you want to (you mentioning printing bookings, which I suspect might need a very rigid format), you're not going to get away from that. HTML is designed to allow variation by browser implementation and by user preference. It's not supposed to look the same everywhere.
If you need accurate, precise print reproduction everywhere, your best bet is to generate some kind of PDL (Page Description Language) on the fly. PDF is the common choice here, and prolly your best bet, since most people are used to it and already have software. Other choices would be PostScript and XPS, but those are much less commonly available in the user community.
Note that "PDF" doesn't have to mean "Adobe"; there are tons of third-party PDF tools out there, including free and FOSS.
Many moons ago, I was working helpdesk at a tiny software company, and started to put together a mickey-mouse database to help me keep track of calls. I named it "Trouble Incident Tracking System".
As you can prolly guess, there weren't any female employees.
"If the 'F' word is banned in your school and the kids all of a sudden decide to say the word 'Squash' in lieu of the naughty word, eventually they become synonymous."
This is why censorship of individual words doesn't work. Language is constantly evolving. If you try to limit it, the very limitation you are attempting to impose affects language. Kind of like the Heisenberg uncertainty principle, but for words.
In Larry Niven's "Known Space" speculative future series, the words "bleep" and "censored" have become profanity. They've been used so much in place of bad words that they themselves take on the meaning.
It works even for words which are not intended to be crude. "Retarded", "moron", "imbecile", all used to be clinical terms. Now they've moved on to "learning disability" or whatever. That will eventually become an insult, too, and then they'll have to move on to something else. "Insensitive clod", perhaps.
"Worse, it means that ALL OF THE SYSTEMS are logical targets in a war. OTH, NASA would not be that kind of a target..."
Cape Canaveral Air Force Station is co-located with Kennedy Space Center. CCAFS is still an active military space port facility. Plus, while NASA may be a "civilian" agency, it's still a government agency. If someone decides they need to start taking out US space capabilities, I highly doubt the "civilian" distinction is going to matter to them, even if the attacker was of the fair-minded type. (To say nothing of the type that prefers high-profile civilian targets.)
"Where are you going to purchase a legit copy of Lotus 1-2-3 not to mention DOS? But you *can* be sued for pirating them, at least technically."
I think the point the author is going for is that while you can be sued for that, the BSA generally doesn't. And while I'm no fan of the BSA and its members, that is a valid point. Just because you *can* sue doesn't mean you *must* sue.
"If you need to stay cutting edge, why not use a rolling distrobution such as Arch or Gentoo?"
The DoD, in general, *really* doesn't like do-it-yourself stuff. Yah, you can run Linux, but it has to be from Officially Approved vendors (Red Hat, SuSE). Only they have the secret decoder ring or whatever it is the DoD wants.
I'm sure any number of arguments against this will occur to people. You learn real quick: What you think doesn't matter for squat. You're in the army now, and they do it the army way.
"You're getting me curious! What are those networks like?"
Things start getting really secure when you go classified. (There's plenty that's sensitive or deserving of security that ain't classified.)
Right away, classified generally means no connections to public networks/communications. (It's in theory possible, with sufficiently sophisticated security software, but practically never done.) Air gap. The only way to transfer data off the secure "island" is via hand-carried media (sneakernet). For most systems, any media mounted on the system is automatically classified to the highest level of the information on the system, so you can't get data *off* easily, either.
Things are classified CONFIDENTIAL, SECRET, or TOP SECRET (in order of increasing sensitivity). To work with something classified, you have to have a personal security clearance at least as good as the classified stuff. Getting a clearance requires filling out a giant form with your life history, including where you've lived, where you've worked, where you went to school, who knew you at all those places, etc. A background investigation follows. The higher the clearance, the more through the investigation.
A lot of classified systems are stand-alone, meaning a single computer with no network. Often, the hard drive will be in a removable carrier. When the system isn't in use, the hard drive is stored in a government-approved safe. Or it's a laptop, and the whole computer is kept in a safe.
Beyond classification levels, some things are put into SAPs ("Special Access Programs", AKA "Compartments"). You need formal, individual approval for each SAP. More paperwork.
A non-uncommon scenario might be: A computer, locked in a safe, locked in a room, inside a secure facility, protected by multiple levels of alarm systems, surveillance cameras, and armed guards.
Then things get *really* tough.
You have TPI, or Two Person Integrity. This means that any time the material is in use, you have to have two people there. They watch each other.
Beyond that, you have TPC, or Two Person Control. The material is guarded at all times (even when not in use) by two people. The people don't know who will be working with in advance of their shift/assignment. The equipment won't operate without both people acting together.
None of the above is special knowledge; you can find it all on Wikipedia. I imagine there is stuff DoD *isn't* telling us about, too.
"In fact the SRB's on the shuttle have exactly this feature, and were used in the Challenger disaster when the SRB's appeared to be heading towards land."
You're thinking of the range safety destruction ordinance. That's something completely different.
The range safety charges are strategically-placed explosives, designed to cause the vehicle to break-up into (relatively) safe fragments, upon remote command. On the shuttle SRBs, they're basically a long strip along the entire length of the rocket, and peal it open like splitting a soup can along the seam. They were indeed used on STS-51-L.
Thrust venting is more like a shutdown. If the shuttle SRBs have thrust venting, it would involve blowing a hole open in the top of the SRB stack, so that the propellant thrust escapes equally from top and bottom.
Thrust venting doesn't inherently destroy the vehicle. Of course, if used in flight, loss of propulsion means gravity takes over, which usually doesn't end well for a rocket. But it can (in theory) also be used before liftoff, to cancel the effect of premature ignition.
Pretty much every rocket launched by NASA or US DOD has range safety charges. I'm not sure if it's "law", but it's certainly mandated at a lower level if not. I'm sure Ares has such, too.
You can't throttle them and you can't turn them off
I've already responded to that in another message. Yet you continue to repeat a statement you know to be, at best, questionable. This makes me wonder what other facts you might be ignoring.
Also they have significantly better performance.
From what I'm told, liquid-fuel rockets have better propellant efficiency, but solid-fuel rockets have better thrust-to-mass ratios, as I explained. But by all means, continue ignoring what I'm saying; that really helps your case.
You do get some warnings ergo the Saturn could and did turn engines off in flight and continued with the mission.
No argument there. That's also happened pre-launch for the shuttle SSMEs, and one of the Gemini missions.
However, liquid rockets also blow up more often than solid rockets, or so I'm told. Hell, even STS-51-L's SRBs kept flying after the ET had blown to bits; they were detonated by the RSO. If it wasn't for the big ass fuel tank right next to them, the O-ring burn-through wouldn't have been a problem. ("Other than that, Mrs. Lincoln, how was the play?")
I'm not convinced that the benefits of solid rockets outweigh the drawbacks, but I'm willing to have an information discussion about it. Are you?
Also those boosters are *not* cheap.
The shuttle SRBs ain't free, but the SSMEs make 'em look downright cheap in comparison.
... the need for solids nill...
I was talking to an actual rocket scientist who worked for Boeing corp. What are your qualifications, if I may ask? Are you just another armchair engineer, as I am myself?
The Range Safety Officer can't let it just crash back to the ground. The stark reality is that in the event of a guidance failure the RSO's job is to activate the destruct system. Although the lives of the astronauts might be lost, the lives of hundreds of people on the ground take precedence. And no, there isn't really going to be time to determine which way the rocket is going. In the time it would take to figure that out, Cocoa Beach could be a flaming inferno.
It appears the RSO has more latitude in the performance of their duties than posts here would suggest. On STS-51-L (the Challenger's last flight), the RSO saw the evidence of explosion and initially thought to recommend no action. It was only once the SRBs appeared to re-stabilize in flight that destruct was recommended. You can read the RSO's statement here:
You can turn a solid. The nozzles on the shuttle SRBs are vectored, for example.
You can't adjust the throttle pattern after manufacturing, but a solid rocket's design can control their rate of burn. They vary the shape and size of the combustion channel.
... even if its not going *that* wrong, the range safety officer is required to detonate...
The RSO for STS-51-L (Challenger's last) didn't detonate until well after the launch vehicle had exploded. Reported, he detonated because it looked like the remains of the SRBs might have been turning towards land, and it was also clear that the vehicle was a total loss. That seems to suggest the RSO has more latitude than you state.
"Well as it's solid fuel, can't they have an alternative emergency nozzle somewhere near the top of the SRB, that could be ignited for the purpose of simply throwing the SRB off-course for a few seconds while the capsule has a chance to get a few hundred meters away?"
Putting that much lateral stress on the vehicle so suddenly would prolly cause a break-up. Most people don't appreciate just how fragile rockets are. They run the ragged edge of technology. Weight is everything on a lift vehicle, so they're always looking for ways to make it lighter. So they have enough structure to withstand nominal forces -- nothing more.
That said, there is something called a "thrust equalizer" or "thrust vent" that's similar to what you describe. Many solid rockets (including the shuttle SRBs) have a hollow shaft down the center of the entire length -- the whole thing burns at once. You get more thrust that way. If you open the top end, then the propellant will vent equally from top and bottom, yielding zero net impulse. I don't know if the shuttle SRBs have this (if they do, "thermal curtain failure" won't help Max after all). I doubt the Ares does, given that the crew is sitting on top of the solid rocket stack.
"100% liquid fuel was always the right way to do. Loose the solids..."
When someone says "solid rocket" most people think of Challenger. The problem there was that the rocket was operated in conditions outside of design specifications. Liquid fuel rockets tend to fail when pushed beyond their limits, too. I've certainly seen plenty of footage of both types exploding.
I asked about this question to an actual rocket scientist not long ago. My take was that liquid fuel seems safer because you can control it off after ignition. His response, in part: "Offhand I know of at least several cases of a liquid fuel engine going 'BOOM!' and everyone being surprised." Apparently many of the failure modes don't allow for any warning; it just explodes before you can do anything. Further, reportedly, simply "turning off" a rocket engine in flight is not as simple as it sounds; the dynamic loads are complex, and doing it wrong can cause the vehicle to break-up. He said that solid rockets are typically more reliable than liquids, because of their simple design. Liquid fuel motors are very complex, and thus cost more to make, and to make reliable.
He also described an aspect of flight dynamics: Rockets launched vertically go through two phases. The first is overcoming the force of gravity to get it airborne; the second accelerates it downrange and into orbit. Solids lend themselves towards the first phase, because they have a high trust-to-mass ratio. In the second phase, propellant efficiency matters more, and then liquid engines are a win.
He did say that the choice of a solid rocket for the first stage of Area was driven entirely by time and cost constraints. There's no way NASA could have designed and tested a liquid-fuel rocket motor of sufficient thrust and reliability within the time and money allotted.
Now, this is just one guy's take, so I'm not accepting it as ultimate truth. But he knows more than I do.
I, too, have a rather romantic vision of the Saturn V, but given that it was only launched about a dozen times, I'm not sure how realistic that vision is.
To paraphrase Carl Sagan in "Pale Blue Dot", any species that does not move off its planet is doomed to extinction.
I like Larry Niven's aphorism better: "The dinosaurs are extinct because they didn't have a space program."
(Someone else posted the aphorism, but they left out the attribution.)
I do wonder just how practical manned exploration/colonization beyond Earth would be given technology foreseeable in the near future, but certainly we could be doing more in Earth orbit, and telepresence exploration of the Solar system seems like a reasonable step.
Slashdot Mirror
"A solid fuel rocket is like a firecracker - once you light it there is nothing you can do to control it in any way. Other systems have to be changed to compensate for that."
From what I'm given to understand, there *are* controls available to a solid fuel rocket. There is thrust vectoring, of course. But they can vary the side and shape of the burn channel, and they can vary the formulation of the fuel. This changes the performance characteristics of the propellant, giving you something like a throttle.
The big difference is this has to be decided at manufacturing time. Obviously, liquid fuel rockets give you more flexibility in that the plan can be changed in-flight. However, I'm also told that the realities of flight dynamics mean there's a fairly narrow range of safe maneuvering options, beyond which the vehicle will breakup. And it isn't like you can just prematurely "turn off" a rocket and expect things to end well. So the reduced control that comes from a solid fuel rocket design is apparently not as big a problem as one might expect at first glance.
Now, I'm not arguing that solid rockets are the best possible option. From what I understand, they just have cost and reliability on their side. And the cost claim has been challenged in a fair fashion elsewhere in this subthread, so I'm even less sure about that now.
"Solid rockets have significantly cheaper R&D costs. The per flight costs are not better. Especially when you are comparing versus a reusable liquid fueled stage."
Again, please provide a reference. A solid rocket is basically propellant in a tube. (Okay, there will be some sophistication at the nozzle for flight control.) A liquid fuel rocket engine is an incredible complex of pipes, pumps, valves, controls, and injectors. They need sophisticated fuel generation and storage facilities.
In particular, I've seen the SSMEs called the most expensive rocket engines ever to fly. A single engine unit costs more than an entire Delta launch. They can only be used a limited number of times, and they have to be rebrurb'ed after every launch.
References:
http://www.donaldfrobertson.com/ssme.html
http://www.outofthecradle.net/archives/2006/05/nasa-chooses-rs-68-main-engine-for-constellation-cargo-launch-vehicle/
"Falcon 9 is an all-liquid rocket, meaning it isn't prone to catastrophic solid propellant explosions like the Ares I is."
Right, it's "prone" to catastrophic liquid propellant explosions instead.
Historically, solid rockets are more reliable when it comes to them not exploding. They're much simpler designs, and much more robust. Heck, parts of the SRBs on STS-51-L (the one that killed Challenger) survived the initial explosion and kept flying. They had to detonate the range safety charges to stop them. If it hadn't been for the giant liquid fuel tank next to the SRBs, the O-ring leak wouldn't have been a problem. (Obviously, since there was a giant liquid fuel tank, that's a huge problem, but the point of discussion is the reliability and robustness of solid rockets, not the STS as a whole.)
Solid rockets are cheaper, simpler, more robust, and have a higher thrust-to-weight ratio. But control options are limited. You can't vary thrust from plan, and once lit they will consume their entire fuel supply. No stop-and-restart.
Liquid rockets are more controllable, restartable, and have better propellant efficiency. But they are more costly, more complex, and more fragile. To quote a rocket scientist I was conversing with, "There are plenty of examples of liquid rockets going BOOM and everyone being surprised."
Now, I believe the mechanics of launch to orbit dictate that you pretty much need at least one liquid fuel stage. SpaceX reasons that you're better off using the same technology everywhere, to reduce overall design, manufacturing, and support costs. I suspect they are correct. If you have to build a good liquid rocket engine, you might as well use it everywhere. Using two different technologies means twice as many problems.
"once the moon landing was no longer politically potent, they killed them (at exactly the same time NASA started sending scientist rather then fighter pilots)."
In fairness, the Apollo "fighter pilot" astronauts are/were prolly smarter than you or I. Neil Armstrong obtained an aerospace engineering degree before he became a test pilot. Buzz Aldrin was an MIT PhD. Yah, they were stick jockeys, too, but they were the elite of that field. They weren't jarheads.
"Next to military gear, space gear is the perfect line of business. Much of it will either be blown up or sent to unrecoverable locations. This means that the customer will always be coming back for more."
For that matter, the military generally wants the stuff that isn't supposed to blow up to last forever.
Of course, lots of that is achieved through sustained maintenance, which is also good for business. But I have to deal with the "disposable" mentality in the commercial sector, and I'm not sure the military doesn't have the right idea there.
"No one tries 'efficient' because no one is motivated and it would actually interefere with their personal fiefdom building."
In fairness, that happens all the time in private companies, too. It's just less public because they're, ya know, private.
I'm not saying this to defend government so much as to also criticize private companies. They both suck.
If there's any conclusion I can reach, it's that large organizations of any type are the problem. When you scale up, you inevitably get longer lines of communications, a higher tolerance for mediocrity (you need more people than the cream of the crop can provide), the need for more formal procedures (to compensate for the first two), deeper pocket to fund fief building, and more places to hide it all.
I think Space-X wins because they're small, nimble, and fresh. And more power to them for it.
"... hoping for a repeat of the Saturn-V's 12/12 record ..."
It's worth pointing out that 12 mission launches is not much data to draw on. And at least one Saturn V component blew up in a test flight, so it was not perfect, either.
I'm not saying the Saturn V wasn't an achievement, or that it wasn't a good design, just that we should beware of romantic illusions.
"Evem early in the game, the solid booster system was known to result in a cost increase of 60% per pound into orbit."
Can you provide a reference for that? I've been told by an actual rocket scientist that solid fuel rockets are significantly cheaper than liquid fuel rockets, especially for the boost phase, where thrust-to-weight matters more than propellant efficiency.
I've also seen inflation-adjusted figures for Saturn V vs STS, and the Saturn V was vastly more expensive. Now, they only flew about two dozen Saturn V's, so they never had a chance to develop economies of scale, but it's not like the STS is a huge win in that department either. The Saturn V also had a much greater total lift capacity, so this may be apples-to-oranges in the first place.
Certainly, liquid fuel rockets have a number of advantages, but I haven't seen anything to suggest cost is one of them.
(Note that I'm not saying the STS SRBs were an overall win. Good design theory won't save a badly run program. I just question the idea that's it's *because* they were solid rockets that costs were high.)
What are the "printing problems" you're having?
If the problem is that you're having trouble making things look the way you want to (you mentioning printing bookings, which I suspect might need a very rigid format), you're not going to get away from that. HTML is designed to allow variation by browser implementation and by user preference. It's not supposed to look the same everywhere.
If you need accurate, precise print reproduction everywhere, your best bet is to generate some kind of PDL (Page Description Language) on the fly. PDF is the common choice here, and prolly your best bet, since most people are used to it and already have software. Other choices would be PostScript and XPS, but those are much less commonly available in the user community.
Note that "PDF" doesn't have to mean "Adobe"; there are tons of third-party PDF tools out there, including free and FOSS.
"Hey here is a nice pic of WinBIOS I found."
AHHHHH!! Damnit, I had gone through years of therapy to get over my exposure to that. You've ruined it all!
Many moons ago, I was working helpdesk at a tiny software company, and started to put together a mickey-mouse database to help me keep track of calls. I named it "Trouble Incident Tracking System".
As you can prolly guess, there weren't any female employees.
"If the 'F' word is banned in your school and the kids all of a sudden decide to say the word 'Squash' in lieu of the naughty word, eventually they become synonymous."
This is why censorship of individual words doesn't work. Language is constantly evolving. If you try to limit it, the very limitation you are attempting to impose affects language. Kind of like the Heisenberg uncertainty principle, but for words. In Larry Niven's "Known Space" speculative future series, the words "bleep" and "censored" have become profanity. They've been used so much in place of bad words that they themselves take on the meaning. It works even for words which are not intended to be crude. "Retarded", "moron", "imbecile", all used to be clinical terms. Now they've moved on to "learning disability" or whatever. That will eventually become an insult, too, and then they'll have to move on to something else. "Insensitive clod", perhaps.
"Worse, it means that ALL OF THE SYSTEMS are logical targets in a war. OTH, NASA would not be that kind of a target ..."
Cape Canaveral Air Force Station is co-located with Kennedy Space Center. CCAFS is still an active military space port facility. Plus, while NASA may be a "civilian" agency, it's still a government agency. If someone decides they need to start taking out US space capabilities, I highly doubt the "civilian" distinction is going to matter to them, even if the attacker was of the fair-minded type. (To say nothing of the type that prefers high-profile civilian targets.)
Just sayin'.
"Every member company of BSA has been found to have 'unauthorized software' [citation needed] "
Self-identifying bullshit. Now *that's* an innovation! Can you automatically call yourself a Nazi, too?
"Where are you going to purchase a legit copy of Lotus 1-2-3 not to mention DOS? But you *can* be sued for pirating them, at least technically."
I think the point the author is going for is that while you can be sued for that, the BSA generally doesn't. And while I'm no fan of the BSA and its members, that is a valid point. Just because you *can* sue doesn't mean you *must* sue.
"If you need to stay cutting edge, why not use a rolling distrobution such as Arch or Gentoo?"
The DoD, in general, *really* doesn't like do-it-yourself stuff. Yah, you can run Linux, but it has to be from Officially Approved vendors (Red Hat, SuSE). Only they have the secret decoder ring or whatever it is the DoD wants.
I'm sure any number of arguments against this will occur to people. You learn real quick: What you think doesn't matter for squat. You're in the army now, and they do it the army way.
(Substitute service branch of your choice.)
"You're getting me curious! What are those networks like?"
Things start getting really secure when you go classified. (There's plenty that's sensitive or deserving of security that ain't classified.)
Right away, classified generally means no connections to public networks/communications. (It's in theory possible, with sufficiently sophisticated security software, but practically never done.) Air gap. The only way to transfer data off the secure "island" is via hand-carried media (sneakernet). For most systems, any media mounted on the system is automatically classified to the highest level of the information on the system, so you can't get data *off* easily, either.
Things are classified CONFIDENTIAL, SECRET, or TOP SECRET (in order of increasing sensitivity). To work with something classified, you have to have a personal security clearance at least as good as the classified stuff. Getting a clearance requires filling out a giant form with your life history, including where you've lived, where you've worked, where you went to school, who knew you at all those places, etc. A background investigation follows. The higher the clearance, the more through the investigation.
A lot of classified systems are stand-alone, meaning a single computer with no network. Often, the hard drive will be in a removable carrier. When the system isn't in use, the hard drive is stored in a government-approved safe. Or it's a laptop, and the whole computer is kept in a safe.
Beyond classification levels, some things are put into SAPs ("Special Access Programs", AKA "Compartments"). You need formal, individual approval for each SAP. More paperwork.
A non-uncommon scenario might be: A computer, locked in a safe, locked in a room, inside a secure facility, protected by multiple levels of alarm systems, surveillance cameras, and armed guards.
Then things get *really* tough.
You have TPI, or Two Person Integrity. This means that any time the material is in use, you have to have two people there. They watch each other.
Beyond that, you have TPC, or Two Person Control. The material is guarded at all times (even when not in use) by two people. The people don't know who will be working with in advance of their shift/assignment. The equipment won't operate without both people acting together.
None of the above is special knowledge; you can find it all on Wikipedia. I imagine there is stuff DoD *isn't* telling us about, too.
Ah. Interesting. Thanks for the info.
"In fact the SRB's on the shuttle have exactly this feature, and were used in the Challenger disaster when the SRB's appeared to be heading towards land."
You're thinking of the range safety destruction ordinance. That's something completely different.
The range safety charges are strategically-placed explosives, designed to cause the vehicle to break-up into (relatively) safe fragments, upon remote command. On the shuttle SRBs, they're basically a long strip along the entire length of the rocket, and peal it open like splitting a soup can along the seam. They were indeed used on STS-51-L.
http://books.google.com/books?id=A3REsJuW2yEC&lpg=RA3-PA185&ots=G8HM7ELnVo&pg=RA3-PA185
Thrust venting is more like a shutdown. If the shuttle SRBs have thrust venting, it would involve blowing a hole open in the top of the SRB stack, so that the propellant thrust escapes equally from top and bottom.
Thrust venting doesn't inherently destroy the vehicle. Of course, if used in flight, loss of propulsion means gravity takes over, which usually doesn't end well for a rocket. But it can (in theory) also be used before liftoff, to cancel the effect of premature ignition.
Pretty much every rocket launched by NASA or US DOD has range safety charges. I'm not sure if it's "law", but it's certainly mandated at a lower level if not. I'm sure Ares has such, too.
You can't throttle them and you can't turn them off
I've already responded to that in another message. Yet you continue to repeat a statement you know to be, at best, questionable. This makes me wonder what other facts you might be ignoring.
Also they have significantly better performance.
From what I'm told, liquid-fuel rockets have better propellant efficiency, but solid-fuel rockets have better thrust-to-mass ratios, as I explained. But by all means, continue ignoring what I'm saying; that really helps your case.
You do get some warnings ergo the Saturn could and did turn engines off in flight and continued with the mission.
No argument there. That's also happened pre-launch for the shuttle SSMEs, and one of the Gemini missions.
However, liquid rockets also blow up more often than solid rockets, or so I'm told. Hell, even STS-51-L's SRBs kept flying after the ET had blown to bits; they were detonated by the RSO. If it wasn't for the big ass fuel tank right next to them, the O-ring burn-through wouldn't have been a problem. ("Other than that, Mrs. Lincoln, how was the play?")
I'm not convinced that the benefits of solid rockets outweigh the drawbacks, but I'm willing to have an information discussion about it. Are you?
Also those boosters are *not* cheap.
The shuttle SRBs ain't free, but the SSMEs make 'em look downright cheap in comparison.
... the need for solids nill ...
I was talking to an actual rocket scientist who worked for Boeing corp. What are your qualifications, if I may ask? Are you just another armchair engineer, as I am myself?
The Range Safety Officer can't let it just crash back to the ground. The stark reality is that in the event of a guidance failure the RSO's job is to activate the destruct system. Although the lives of the astronauts might be lost, the lives of hundreds of people on the ground take precedence. And no, there isn't really going to be time to determine which way the rocket is going. In the time it would take to figure that out, Cocoa Beach could be a flaming inferno.
It appears the RSO has more latitude in the performance of their duties than posts here would suggest. On STS-51-L (the Challenger's last flight), the RSO saw the evidence of explosion and initially thought to recommend no action. It was only once the SRBs appeared to re-stabilize in flight that destruct was recommended. You can read the RSO's statement here:
http://books.google.com/books?id=A3REsJuW2yEC&lpg=RA3-PA185&ots=G8HM7ELnVo&pg=RA3-PA185
Since you can't turn or throttle a solid ...
You can turn a solid. The nozzles on the shuttle SRBs are vectored, for example.
You can't adjust the throttle pattern after manufacturing, but a solid rocket's design can control their rate of burn. They vary the shape and size of the combustion channel.
You can neutralize a solid rocket with trust venting. I explained that elsewhere in this story.
... even if its not going *that* wrong, the range safety officer is required to detonate...
The RSO for STS-51-L (Challenger's last) didn't detonate until well after the launch vehicle had exploded. Reported, he detonated because it looked like the remains of the SRBs might have been turning towards land, and it was also clear that the vehicle was a total loss. That seems to suggest the RSO has more latitude than you state.
"Well as it's solid fuel, can't they have an alternative emergency nozzle somewhere near the top of the SRB, that could be ignited for the purpose of simply throwing the SRB off-course for a few seconds while the capsule has a chance to get a few hundred meters away?"
Putting that much lateral stress on the vehicle so suddenly would prolly cause a break-up. Most people don't appreciate just how fragile rockets are. They run the ragged edge of technology. Weight is everything on a lift vehicle, so they're always looking for ways to make it lighter. So they have enough structure to withstand nominal forces -- nothing more.
That said, there is something called a "thrust equalizer" or "thrust vent" that's similar to what you describe. Many solid rockets (including the shuttle SRBs) have a hollow shaft down the center of the entire length -- the whole thing burns at once. You get more thrust that way. If you open the top end, then the propellant will vent equally from top and bottom, yielding zero net impulse. I don't know if the shuttle SRBs have this (if they do, "thermal curtain failure" won't help Max after all). I doubt the Ares does, given that the crew is sitting on top of the solid rocket stack.
"100% liquid fuel was always the right way to do. Loose the solids..."
When someone says "solid rocket" most people think of Challenger. The problem there was that the rocket was operated in conditions outside of design specifications. Liquid fuel rockets tend to fail when pushed beyond their limits, too. I've certainly seen plenty of footage of both types exploding.
I asked about this question to an actual rocket scientist not long ago. My take was that liquid fuel seems safer because you can control it off after ignition. His response, in part: "Offhand I know of at least several cases of a liquid fuel engine going 'BOOM!' and everyone being surprised." Apparently many of the failure modes don't allow for any warning; it just explodes before you can do anything. Further, reportedly, simply "turning off" a rocket engine in flight is not as simple as it sounds; the dynamic loads are complex, and doing it wrong can cause the vehicle to break-up. He said that solid rockets are typically more reliable than liquids, because of their simple design. Liquid fuel motors are very complex, and thus cost more to make, and to make reliable.
He also described an aspect of flight dynamics: Rockets launched vertically go through two phases. The first is overcoming the force of gravity to get it airborne; the second accelerates it downrange and into orbit. Solids lend themselves towards the first phase, because they have a high trust-to-mass ratio. In the second phase, propellant efficiency matters more, and then liquid engines are a win.
He did say that the choice of a solid rocket for the first stage of Area was driven entirely by time and cost constraints. There's no way NASA could have designed and tested a liquid-fuel rocket motor of sufficient thrust and reliability within the time and money allotted.
Now, this is just one guy's take, so I'm not accepting it as ultimate truth. But he knows more than I do.
I, too, have a rather romantic vision of the Saturn V, but given that it was only launched about a dozen times, I'm not sure how realistic that vision is.
To paraphrase Carl Sagan in "Pale Blue Dot", any species that does not move off its planet is doomed to extinction.
I like Larry Niven's aphorism better: "The dinosaurs are extinct because they didn't have a space program."
(Someone else posted the aphorism, but they left out the attribution.)
I do wonder just how practical manned exploration/colonization beyond Earth would be given technology foreseeable in the near future, but certainly we could be doing more in Earth orbit, and telepresence exploration of the Solar system seems like a reasonable step.