Venturestar looks great until you actually start running the numbers on it. Any single stage to orbit craft has to have an insanely low structural mass fraction. something like.05-.1 What those numbers mean is that for ever kilogram of payload, structure, engines, people etc, you need 10-20 kg of fuel. Things get better if youre dropping structure and fuel tanks off along the way, like the shuttle. Howevwer, if you had to carry the SRB's and the external tank all the way to orbit, the shuttle would be twice as big as it currently is and still have the same payload capacity. Venturestar tried to get around this with new efficient engine technology and carbon fiber fuel tanks. The Carbon fiber fuel tanks would have significantly reduced the tank weight. Unfortunately, fuel leakd throguh the carbon skin and into the honeycomb underneath. When the tanks emptied the fuel vaporized and popped a hole in the tank. Not very good for reusability. Engine performance can only be tweaked so far. The limits are the chemical energy that is released from a given reation. Ultimately all rockets get killed by the rocket equation. dV=g0*Isp*ln(mf/m0) g0=gravity=9.81 m/s^2 Isp= the specific impulse of the fuel (depends on the fuel) the best we can get is about 450-460 for liquid oxygen-liquid hydrogen,mf=final mass of your vehicle m0=initial mass of your vehicle. dV= total change in velocity for the vehicle. Orbital velocity is about 7600 m/s plus you need to add on a bit more for drag as you go through the atmosphere, and the energy you need to actually reach altitude. A good number is 10000 m/s Run the numbers yourself and see how much mass you need in fuel to launch a certain mas of craft. Keep in mind that as you increase the amount of fuel you increase the amount of tank mass and other masses like wiring and computers.
Agreed. I think we need to replace the shuttle system. It's 30 year old technology.
Just because the technology is old doesnt make it unuseful. What does the shuttle ultimately land on? Wheels. Wheels have been around for thousands of years. They are one of the oldest technologies known to mankind. Why does the shuttle use wheels to land on and not some sort of new technology? Because wheels work, wheels are well understood, and wheels are cheap to make. Just because a technology wasnt discovered in the last 10 years doesnt make it bad. That being said, the point i think you were trying to make is that the shuttles themselves are old. Like an old car, except that columbia had tens of millions of miles on it instead of 300k that an old junker car would have. Metal fatigue begins to set in, and no amount of inspections can stop that. The fact that the technology is old does not nescisarily make it bad. The fact that the vehicles themselves were old does present a problem.
According to the NASA press conference this afternoon, A progress resupply was already scheduled to launch tomorrow, and will still do so (hooray for independant redundant systems) And will bring the current space station residents enough supplies to last till june. Theoretically, the station could be supplied entirely with progress capsules and crew rotation could occur with soyuz capsules, meaning that ultimately this shouldnt have much of an effect on day to daqy operations. This does mean however that construction on the station is at a standstill for the 2+ years it will take to recertify the shuttles.
One could argue that its harder to design and build things than to blow them up, but as an aerospace engineer, I say that its harder to blow things up in a technologically cool way than to build things. Giant death lasers from space anyone?
pssh, that is so mid 1990's. I remember in like 1995 two of myh neighbors built their own out of pvc tube. They could shoot a spud three blocks over, it rocked!
Coming soon, cocaine free crack, produced by dwarves deep below the surface of the earth. Seriously, if you remove the addicting agent from cigarettes, youre just inhaling smoke all day, and nobody wants to do that unless theyre addicted.
Say for arguments sake that my music library was recently destroyed due to a harddrive issue. I download maybe 1 song a week (if that) but ive got over 600 songs, i could get busted if i restored my collection in one day? (hypothetically, assuming i had such a collection. At any rate, I would LOVE to see the RIAA go after EVERYONE who has downloaded an MP3 from the internet. A word to the wise, if you do get busted for this, demand a jury trial and dont take any plea bargains. For that matter, dont hire an attourney, let the court provide one. If everyone who gets busted does this, pretty soon the court system breaks down. Currenttly only 5% of cases are tried by a jury, the other 95% are pleabargained down.
Actually, there are 4 reviews that give the produect a 5. Two of them are top 500 reviewers and a third is in the top 1500. All of the good reviews are within the first few days of the products release and they all sound like they could have come from the back of the box.
We do it for the same reason you got yoru phone service from AT&T in the 70's: Where else are you going to go? You said it yourself, 90% of the legitimate music is distributed by RIAA Member companies, same with movies. If you want to listen to mainstream music and watch mainstream movies, they have a monopoly. Yes, you could listen to to music from other companies or watch movies from non MPAA companies, But I want to see LOTR, I dont want to see something else, so its either Pay the MPAA for the privelige or illegally download it off the net.
The landings on the moon was a technological aberration that only occured at great expense in money, manpower and time. For example, if Queen victoria had thrown enough resources at Charles Babbage, they might have created a computer as powerful as the first electric computer. this would have been a technological achievement at the time as landing a man on the moon. Even if babbage and whatever people were on his team had succeeded, the technological underpinnings for a practical computer were not in place yet. Eniac may have been built in the 30s or late 20's instead due to the leaps from the project, but it wouldnt have started the revolution itself. The same can be said for the apollo program. Many technologies were advanced due to the program, fuel cells, computers, powder based drink mixes, but the ability to travel to other planets wasnt one of them. Also keep in mind that these things take time. The Americas werent colonized in 1493, or 1494 or 1524. The first real colonies came in the late 1500's and colonization began in earnest in the early 1600s, over 100 years after it was proven that america could be accessed reliably from europe by sea. Space is at least as hostile an environment to us now as the sea was to sailors in the 15th century. We will get into space, but i t will take time, and we will go there for the same reason europeans came to america: to get rich. Just as soon as they figure out how.
Agreed. The problem with things today is that people thingk that things have to be "thhe latest" or "the highest tech" in order to work well. Case in point: calssrooms could have high tech whiteboards that wirelessly update notes to everyones laptop. Cost tens to hundreds of thousands of dollars, not to mention the cost of the laptops for the students. Or you could use a black board with chalk and have the students take notes. Educational value is higher when people have to write things down themselves, plus you dont have to spend 50000 on a chalkboard.
but pi does include the numbers 0 thru 9, and is not just composed of random digits of 2 or 3 numbers. Even if it were, you could convert it to binary or some other base and extract the information. Take your example, convert the sequence to binary and it does contain any posible combination of binary numbers. Yes it doesnt contain 9 directly, but it does contain the binary representation of 9 (1001)
But this is already true. Given an INFINITE string of whole numbers, any noninfinite string of whole numbers is included.Digitally encoded, all the books of humanity, all the MP3s, all the pr0n on the internet are found somewhere in pi, Because the finite string of numbers that defines that file is located somewhere in the infinite string of numbers that is pi. Not only that but the file is in every conceivable format that has ever been discovered or ever will be. And every alien file in the universe is in there too. Its the same principle as having an infinite number of monkeeys at an infinite number of typewriters. Not only will the monkeys write all the greatest books of mankind, theyll write every book ever. Heres an interesting infinity problem to ponder: Given a horse race with an infinite number of horses, what are the odds of you winning a bet on a horse? Keep in mind that 1 horse does actually win. What would the payoff be if you won, given the odds are simply calculated at 1/# of horses)
Lets look at return on investment for the space program as a whole. Over the course of the space program probably 2-300 Billion dollars have been invested in R&D and Space based activities. The market for GPS related productsis predicted to be $45 billion a year in the year 2006. At that rate, the initial investment for the entire space program will be paid back to the economy in 6 years. The market for satellite communications is also in the tens of billions a year category. Look at the market for satellite TV, Satellite radio. The launch industry alone is a 10 billion dollar a year industry, and the majority of those launches are commercial ones. It took 30 years to get to this point. Can you think of any VC companies that invest several hundred billion dollars on something that is going to have a return 20-30 years out? Yes, the space station may seem like a giant boondoggle now, but whats it going to be 20-30 years out? How many private commercial space stations will there be out there? Think im joking? if you were around in 1957 did you ever think that there would be companies based exclusively on owning satellites? Probably not.
What would you trust more, a well developped and well researched almost 200 year old technology (the first steam train ran in 1804 [schoolnet.co.uk]), or a new, extremely complex technology that has yet to carry it's first passenger???
Nine- One of my commandments is "thou shalt not commit adultury" Pornography is considered adultury. Not only are you committing this sin, you are helping others commit it. Part of MY PLAN (tm) included having Keanu Reeves and Lawrence Fishburne become actors specifically so that they could make the Matrix (and sequels) in order to punish you for your sins. Have a nice day. -God
If NASA wants to do some useful science on the ISS, they should start researching equipment that doesn't break down in orbit. Even if the ISS doesn't provide any great research or achievements, why not use it to validate methods of building things and keeping stuff in orbit reliably?
NASA could stop sending up identical copies of the gyros and oxygen scrubbers that break every week, and start sending up experimental items to find one with a better failure ratio (while of course keeping spares handy to avert disaster, I'm sure).
As somone who has actually designed hardware that is currently on the Hubble space telescope, I think im qualified to answer your assertion that Nasa should just "design better hardware" When doing hardware design, you live within constraints. Widget X must perform function Y with a 10% margin of error, and it must be as light as possible. And has to fit with widgets A-R that have already been designed and fabricated, so they cant be changed. And it has to be light. But it also has to be strong enough to do its job. And it cant break down more than 9 times out of 10 And it has to be light. And then you have to redesign it because widget F that you have to interface with changed and now your widget doesnt work anymore. And did i mention it has to be light? Finally if humans are involved all the requirements are multiplied bby 10 because no human has ever been lost in space and damned if itll happen on my watch. Heres the thing, NASA only sends stuff up thats been proven to work either through extensive ground testing or flight testing. But its only designed to work with a 10-40% margin of error. In other words, if your gyro is on orbit for 10 years, and thats what it was designed for, its only gaurenteed to last 1 more year. Thats why they carry spares. Experimental new forms of equipment dont decrease the failure rate, they increase it. If you want to do your testing in orbit, fine but dont rip out the main computer and replace it with a beowulf cluster of linux running pocket PC's and expect it not to fail. Space is a harsh environment. You have to design hardware to withstand a temperature range of up to 600 degrees F, and the radiation tends to fry any normal electronics. Theres a reason they only have P1 processors. Processors have to be specially adapted for the radiation so they dont immediatly throw a transistor and fry. Bottom line is Space isnt earth, earth rules on manufacturing dont apply.
The tables and chairs in the park aren't concrete or nailed down.
There are chairs? When I visited NYC the one thing that i niticed the most (after walking around all day) is that there is nowhere to sit that isnt on the goround or doesnt require you to buy something first pretty much anywhere in the city. In times square there is a little park with benches in it. This park is fenced off from the general public. Despite this there was a bum sleeping on the bench. NYC's solution to the homeless isnt "build more homeless shelters" its "get rid of places where the homeless can sleep" because that will certainly solve the problem.
Slashdot Mirror
Venturestar looks great until you actually start running the numbers on it. Any single stage to orbit craft has to have an insanely low structural mass fraction. something like .05-.1 What those numbers mean is that for ever kilogram of payload, structure, engines, people etc, you need 10-20 kg of fuel. Things get better if youre dropping structure and fuel tanks off along the way, like the shuttle. Howevwer, if you had to carry the SRB's and the external tank all the way to orbit, the shuttle would be twice as big as it currently is and still have the same payload capacity. Venturestar tried to get around this with new efficient engine technology and carbon fiber fuel tanks. The Carbon fiber fuel tanks would have significantly reduced the tank weight. Unfortunately, fuel leakd throguh the carbon skin and into the honeycomb underneath. When the tanks emptied the fuel vaporized and popped a hole in the tank. Not very good for reusability. Engine performance can only be tweaked so far. The limits are the chemical energy that is released from a given reation. Ultimately all rockets get killed by the rocket equation. dV=g0*Isp*ln(mf/m0) g0=gravity=9.81 m/s^2 Isp= the specific impulse of the fuel (depends on the fuel) the best we can get is about 450-460 for liquid oxygen-liquid hydrogen ,mf=final mass of your vehicle m0=initial mass of your vehicle. dV= total change in velocity for the vehicle. Orbital velocity is about 7600 m/s plus you need to add on a bit more for drag as you go through the atmosphere, and the energy you need to actually reach altitude. A good number is 10000 m/s Run the numbers yourself and see how much mass you need in fuel to launch a certain mas of craft. Keep in mind that as you increase the amount of fuel you increase the amount of tank mass and other masses like wiring and computers.
Just because the technology is old doesnt make it unuseful. What does the shuttle ultimately land on? Wheels. Wheels have been around for thousands of years. They are one of the oldest technologies known to mankind. Why does the shuttle use wheels to land on and not some sort of new technology? Because wheels work, wheels are well understood, and wheels are cheap to make. Just because a technology wasnt discovered in the last 10 years doesnt make it bad. That being said, the point i think you were trying to make is that the shuttles themselves are old. Like an old car, except that columbia had tens of millions of miles on it instead of 300k that an old junker car would have. Metal fatigue begins to set in, and no amount of inspections can stop that. The fact that the technology is old does not nescisarily make it bad. The fact that the vehicles themselves were old does present a problem.
According to the NASA press conference this afternoon, A progress resupply was already scheduled to launch tomorrow, and will still do so (hooray for independant redundant systems) And will bring the current space station residents enough supplies to last till june. Theoretically, the station could be supplied entirely with progress capsules and crew rotation could occur with soyuz capsules, meaning that ultimately this shouldnt have much of an effect on day to daqy operations. This does mean however that construction on the station is at a standstill for the 2+ years it will take to recertify the shuttles.
One could argue that its harder to design and build things than to blow them up, but as an aerospace engineer, I say that its harder to blow things up in a technologically cool way than to build things. Giant death lasers from space anyone?
pssh, that is so mid 1990's. I remember in like 1995 two of myh neighbors built their own out of pvc tube. They could shoot a spud three blocks over, it rocked!
Coming soon, cocaine free crack, produced by dwarves deep below the surface of the earth. Seriously, if you remove the addicting agent from cigarettes, youre just inhaling smoke all day, and nobody wants to do that unless theyre addicted.
What was it like giving birth to kyle?
Say for arguments sake that my music library was recently destroyed due to a harddrive issue. I download maybe 1 song a week (if that) but ive got over 600 songs, i could get busted if i restored my collection in one day? (hypothetically, assuming i had such a collection. At any rate, I would LOVE to see the RIAA go after EVERYONE who has downloaded an MP3 from the internet. A word to the wise, if you do get busted for this, demand a jury trial and dont take any plea bargains. For that matter, dont hire an attourney, let the court provide one. If everyone who gets busted does this, pretty soon the court system breaks down. Currenttly only 5% of cases are tried by a jury, the other 95% are pleabargained down.
Actually, there are 4 reviews that give the produect a 5. Two of them are top 500 reviewers and a third is in the top 1500. All of the good reviews are within the first few days of the products release and they all sound like they could have come from the back of the box.
We do it for the same reason you got yoru phone service from AT&T in the 70's: Where else are you going to go? You said it yourself, 90% of the legitimate music is distributed by RIAA Member companies, same with movies. If you want to listen to mainstream music and watch mainstream movies, they have a monopoly. Yes, you could listen to to music from other companies or watch movies from non MPAA companies, But I want to see LOTR, I dont want to see something else, so its either Pay the MPAA for the privelige or illegally download it off the net.
The landings on the moon was a technological aberration that only occured at great expense in money, manpower and time. For example, if Queen victoria had thrown enough resources at Charles Babbage, they might have created a computer as powerful as the first electric computer. this would have been a technological achievement at the time as landing a man on the moon. Even if babbage and whatever people were on his team had succeeded, the technological underpinnings for a practical computer were not in place yet. Eniac may have been built in the 30s or late 20's instead due to the leaps from the project, but it wouldnt have started the revolution itself. The same can be said for the apollo program. Many technologies were advanced due to the program, fuel cells, computers, powder based drink mixes, but the ability to travel to other planets wasnt one of them. Also keep in mind that these things take time. The Americas werent colonized in 1493, or 1494 or 1524. The first real colonies came in the late 1500's and colonization began in earnest in the early 1600s, over 100 years after it was proven that america could be accessed reliably from europe by sea. Space is at least as hostile an environment to us now as the sea was to sailors in the 15th century. We will get into space, but i t will take time, and we will go there for the same reason europeans came to america: to get rich. Just as soon as they figure out how.
Agreed. The problem with things today is that people thingk that things have to be "thhe latest" or "the highest tech" in order to work well. Case in point: calssrooms could have high tech whiteboards that wirelessly update notes to everyones laptop. Cost tens to hundreds of thousands of dollars, not to mention the cost of the laptops for the students. Or you could use a black board with chalk and have the students take notes. Educational value is higher when people have to write things down themselves, plus you dont have to spend 50000 on a chalkboard.
Actually, what was available was "King of Circular Objects: Multiple Battlements" and not the two towers at all.
but pi does include the numbers 0 thru 9, and is not just composed of random digits of 2 or 3 numbers. Even if it were, you could convert it to binary or some other base and extract the information. Take your example, convert the sequence to binary and it does contain any posible combination of binary numbers. Yes it doesnt contain 9 directly, but it does contain the binary representation of 9 (1001)
but the sequence isnt random, pi's sequence is.
But this is already true. Given an INFINITE string of whole numbers, any noninfinite string of whole numbers is included.Digitally encoded, all the books of humanity, all the MP3s, all the pr0n on the internet are found somewhere in pi, Because the finite string of numbers that defines that file is located somewhere in the infinite string of numbers that is pi. Not only that but the file is in every conceivable format that has ever been discovered or ever will be. And every alien file in the universe is in there too. Its the same principle as having an infinite number of monkeeys at an infinite number of typewriters. Not only will the monkeys write all the greatest books of mankind, theyll write every book ever. Heres an interesting infinity problem to ponder: Given a horse race with an infinite number of horses, what are the odds of you winning a bet on a horse? Keep in mind that 1 horse does actually win. What would the payoff be if you won, given the odds are simply calculated at 1/# of horses)
Lets look at return on investment for the space program as a whole. Over the course of the space program probably 2-300 Billion dollars have been invested in R&D and Space based activities. The market for GPS related productsis predicted to be $45 billion a year in the year 2006. At that rate, the initial investment for the entire space program will be paid back to the economy in 6 years. The market for satellite communications is also in the tens of billions a year category. Look at the market for satellite TV, Satellite radio. The launch industry alone is a 10 billion dollar a year industry, and the majority of those launches are commercial ones. It took 30 years to get to this point. Can you think of any VC companies that invest several hundred billion dollars on something that is going to have a return 20-30 years out? Yes, the space station may seem like a giant boondoggle now, but whats it going to be 20-30 years out? How many private commercial space stations will there be out there? Think im joking? if you were around in 1957 did you ever think that there would be companies based exclusively on owning satellites? Probably not.
A more accurate quote would be "Commodore hired engineers, Aple hired engineers and marketers, Microsoft hired marketers"
Thats exactly what they said in 1803.
My favorite is Scientology. Talk about a sci-fi universe with a religious following!
Nine-
One of my commandments is "thou shalt not commit adultury" Pornography is considered adultury. Not only are you committing this sin, you are helping others commit it. Part of MY PLAN (tm) included having Keanu Reeves and Lawrence Fishburne become actors specifically so that they could make the Matrix (and sequels) in order to punish you for your sins. Have a nice day.
-God
NASA could stop sending up identical copies of the gyros and oxygen scrubbers that break every week, and start sending up experimental items to find one with a better failure ratio (while of course keeping spares handy to avert disaster, I'm sure).
As somone who has actually designed hardware that is currently on the Hubble space telescope, I think im qualified to answer your assertion that Nasa should just "design better hardware" When doing hardware design, you live within constraints. Widget X must perform function Y with a 10% margin of error, and it must be as light as possible. And has to fit with widgets A-R that have already been designed and fabricated, so they cant be changed. And it has to be light. But it also has to be strong enough to do its job. And it cant break down more than 9 times out of 10 And it has to be light. And then you have to redesign it because widget F that you have to interface with changed and now your widget doesnt work anymore. And did i mention it has to be light? Finally if humans are involved all the requirements are multiplied bby 10 because no human has ever been lost in space and damned if itll happen on my watch. Heres the thing, NASA only sends stuff up thats been proven to work either through extensive ground testing or flight testing. But its only designed to work with a 10-40% margin of error. In other words, if your gyro is on orbit for 10 years, and thats what it was designed for, its only gaurenteed to last 1 more year. Thats why they carry spares. Experimental new forms of equipment dont decrease the failure rate, they increase it. If you want to do your testing in orbit, fine but dont rip out the main computer and replace it with a beowulf cluster of linux running pocket PC's and expect it not to fail. Space is a harsh environment. You have to design hardware to withstand a temperature range of up to 600 degrees F, and the radiation tends to fry any normal electronics. Theres a reason they only have P1 processors. Processors have to be specially adapted for the radiation so they dont immediatly throw a transistor and fry. Bottom line is Space isnt earth, earth rules on manufacturing dont apply.
There are chairs? When I visited NYC the one thing that i niticed the most (after walking around all day) is that there is nowhere to sit that isnt on the goround or doesnt require you to buy something first pretty much anywhere in the city. In times square there is a little park with benches in it. This park is fenced off from the general public. Despite this there was a bum sleeping on the bench. NYC's solution to the homeless isnt "build more homeless shelters" its "get rid of places where the homeless can sleep" because that will certainly solve the problem.
Or a more apt analogy, Proprietary software is like only being able to watch the movie, and not read the book.
Actually he already owed that much in student loans from going to school in the United States.