No, you CAN go 'upstream' with a solar sail. You have to remember, the sail isn't flying straight away from the sun, it's starting in a solar orbit (the same as earth) and sprialing out into a larger orbit (pluto or whereever it's going). To go 'downwind' you put the sail at 45 degrees, between the orbital direction adn the sunlight direction, with the read side closer to the sun. The light bounces at a right angle and increases the orbital speed and makes the orbit sprial outwards. You put the sail 45 degrees in the other direction, with the front towards the sun, and the push is in the opposite direction of the orbit, and slows the ship, making the orbit spiral towards the sun.
The key is to not think of it as going straight downwind, with the sail pushing away from the sun, but always being on a reach (sailing term for perpendicular to the wind) and using the 'wind' to increase or decrease orbital speed. 0 fuel required, just a couple solar cells to get power to move the sail, and you can go anywhere in the solar system.
The satellite is attached to the sail, how would it crash into it?
It really is simple. You put the sail at a 45 degree angle to the sun, with the rear side towards the sun, and you increase your orbital speed and move away from the sun. 45 degrees with the front towards the sun and you lose orbital speed and move closer to the sun.
Moving the sail is simple, if the satellite can rotate freely in the center of the sail, you just turn the satellite one way (by pushing against the sail, not thrusters) and the sail will turn the other way.
The problem is, it won't work as well the other way around. For penguin, it would be free advertising. For katie j, it was more like a free slashdotting for 4 years.
You missed the point of the article. We can detect jupiter sized planets, the problem is, every one we've seen has been way closer to the star than jupiter is to our sun, we haven't found a single solar system like our own. Aliens looking towards our gas giants would see something different than all the rest of the nearby systems.
That the title of the book was the same as a website is mere lucky coincidence.
That's the part where you're totally wrong. There's no coincidence, they KNEW about the site BEFORE they titled the book. The original title of the book was girl.com, they changed it because girl.com is (or was) a porn site. Do you think they didn't even try loading katie.com (4 years old by that time) before giving that title to the book?
You're missing the point. It's not cut-rate, the american equivilent is massivly overpriced. American aerospace companies massivly inflate their prices because their client is the US government, who can and will pay those insane amounts.
You have to set an end to the mission at some point, you can't just launch them and expect a million a day to keep them going until they die. Besides, this isn't "once they're already there", this is "mission's over and they're still running, much better than expected".
It's simple really. As the elevator starts to lean (the beginning of the so-called wrap around), the cable it no longer perpendicular with the ground. If it's not perpendicular to the ground, there will be a tangental force on the ground slowing the earth (immeasurable ammount) and likewise the opposite force on the counterweight speeding up its orbit, correcting the lean.
In reality, you don't get a wrap around, you get a giant pendulum, which is easily corrected. A launch when the pendulum is still or swinging opposite earth's rotation will increase the magnitude of the pendulum swing. A launch that happens when the pendulum is swinging the same direction as earth's rotation will steal energy away from the swing and lower the magnitude of the pendulum swing.
That's why you take it higher than 200 miles, drop it into an eliptical orbit, then correct the orbit with a couple cheap engine burns (very very cheap relative to an all out launch).
Yeah but considering the cable is only a meter or so wide, and the earth is 40 million meters or so around the equator(at the surface, even farther at orbital altitudes), the odds are pretty damn low of a collision with space junk. And considering we can track most of it now, and by the time this is built we'll have even better tracking, it should be trivial to predict a possible impact well in advance and swing the cable a couple km or so out of the way.
The whole elevator would swing like a pendulum. Which makes it trivial to counteract, you simply time the climb to happen when it's in the forward part of the swing, and you'll be stealing momentum from the pendulum, lowering the magnitude of the swing.
Billions is an understatement. You'd probably have to launch the rocky mountains (all of them) into orbit to have a measureable effect (like 1 second longer days).
It's easier than most people think, you don't need to capture an asteroid. You send up a small counterweight along with the initial spool of cable, and as the first cable unspools downward from geosync, the counterweight moves up. You end up with the first strand of cable fully extended with a small counterweight, just enough to hold itself and a small payload. From there it's trivial, to add more cable you carry it up the initial cable, and to add more counterweight you have the cable-laying climbers go all the way to the end and become part of the counterweight, and/or send separate climbers to carry up the counterweight.
I think the precision needed for interferometry requires a physical connection between the two telescopes, to hold them in position relative to each other with great accuracy. You can't digitize the images from two telescopes and combine them later for interferometry, you have to make the light gathered by the 2 scopes interfere (hense, interferometry). So basically, you can't pull it off with scopes that are disconnected and too far apart.
Why would they be able to see farther? Even if they launched it out of the solar system, which would cost billions and take many years, it would only be like.01% closer to the nearest star.
You're right, I meant Free, but everyone knew what I meant. The post I was replying to seemed to imply that because the product was easy to copy, it had no value.
Quote: What is the value of something if it can be copied (reproduced) for (near to) zero cost?
Fact is, after a song, a movie and anything else which can be stored in digital form has been produced, its value is as high as the cost of reproducing and distributing it. Using cheap PCs and broadband internet, this cost is usually pretty much negligible.
Fact is, after a song, a movie and anything else which can be stored in digital form has been produced, its value is as high as the cost of reproducing and distributing it. Using cheap PCs and broadband internet, this cost is usually pretty much negligible.
So you're saying copyright is pointless? How about open source software? Should anyone be able to steal the code and put it in their closed source project, just because it's easy?
There's this little thing called 'gravity' I heard about recently, and wouldn't you know it, it actually affects the course of projectiles! And all this time I thought bullets just went in a straight line until they hit something!
Slashdot Mirror
No, you CAN go 'upstream' with a solar sail. You have to remember, the sail isn't flying straight away from the sun, it's starting in a solar orbit (the same as earth) and sprialing out into a larger orbit (pluto or whereever it's going). To go 'downwind' you put the sail at 45 degrees, between the orbital direction adn the sunlight direction, with the read side closer to the sun. The light bounces at a right angle and increases the orbital speed and makes the orbit sprial outwards. You put the sail 45 degrees in the other direction, with the front towards the sun, and the push is in the opposite direction of the orbit, and slows the ship, making the orbit spiral towards the sun.
The key is to not think of it as going straight downwind, with the sail pushing away from the sun, but always being on a reach (sailing term for perpendicular to the wind) and using the 'wind' to increase or decrease orbital speed. 0 fuel required, just a couple solar cells to get power to move the sail, and you can go anywhere in the solar system.
The satellite is attached to the sail, how would it crash into it?
It really is simple. You put the sail at a 45 degree angle to the sun, with the rear side towards the sun, and you increase your orbital speed and move away from the sun. 45 degrees with the front towards the sun and you lose orbital speed and move closer to the sun.
Moving the sail is simple, if the satellite can rotate freely in the center of the sail, you just turn the satellite one way (by pushing against the sail, not thrusters) and the sail will turn the other way.
Simple. If you put all that into a solar car (using the current technology) it'll be too heavy to move.
The problem is, it won't work as well the other way around. For penguin, it would be free advertising. For katie j, it was more like a free slashdotting for 4 years.
You missed the point of the article. We can detect jupiter sized planets, the problem is, every one we've seen has been way closer to the star than jupiter is to our sun, we haven't found a single solar system like our own. Aliens looking towards our gas giants would see something different than all the rest of the nearby systems.
That the title of the book was the same as a website is mere lucky coincidence.
That's the part where you're totally wrong. There's no coincidence, they KNEW about the site BEFORE they titled the book. The original title of the book was girl.com, they changed it because girl.com is (or was) a porn site. Do you think they didn't even try loading katie.com (4 years old by that time) before giving that title to the book?
You're thinking of copyright. Trademarks need to be registered.
Well it's Preskill's choice of encyclopedias, so Hawking can't just be a wiseass and give him a link to wikipedia. :)
You're missing the point. It's not cut-rate, the american equivilent is massivly overpriced. American aerospace companies massivly inflate their prices because their client is the US government, who can and will pay those insane amounts.
You have to set an end to the mission at some point, you can't just launch them and expect a million a day to keep them going until they die. Besides, this isn't "once they're already there", this is "mission's over and they're still running, much better than expected".
nasa won't get more money. The rover team is asking for funding FROM nasa.
It's simple really. As the elevator starts to lean (the beginning of the so-called wrap around), the cable it no longer perpendicular with the ground. If it's not perpendicular to the ground, there will be a tangental force on the ground slowing the earth (immeasurable ammount) and likewise the opposite force on the counterweight speeding up its orbit, correcting the lean.
In reality, you don't get a wrap around, you get a giant pendulum, which is easily corrected. A launch when the pendulum is still or swinging opposite earth's rotation will increase the magnitude of the pendulum swing. A launch that happens when the pendulum is swinging the same direction as earth's rotation will steal energy away from the swing and lower the magnitude of the pendulum swing.
That's why you take it higher than 200 miles, drop it into an eliptical orbit, then correct the orbit with a couple cheap engine burns (very very cheap relative to an all out launch).
Yeah but considering the cable is only a meter or so wide, and the earth is 40 million meters or so around the equator(at the surface, even farther at orbital altitudes), the odds are pretty damn low of a collision with space junk. And considering we can track most of it now, and by the time this is built we'll have even better tracking, it should be trivial to predict a possible impact well in advance and swing the cable a couple km or so out of the way.
The whole elevator would swing like a pendulum. Which makes it trivial to counteract, you simply time the climb to happen when it's in the forward part of the swing, and you'll be stealing momentum from the pendulum, lowering the magnitude of the swing.
Billions is an understatement. You'd probably have to launch the rocky mountains (all of them) into orbit to have a measureable effect (like 1 second longer days).
I don't think diameter is the right word, it's going to be a ribbon not a cable. It'll be several feet in width, but paper thin.
It's easier than most people think, you don't need to capture an asteroid. You send up a small counterweight along with the initial spool of cable, and as the first cable unspools downward from geosync, the counterweight moves up. You end up with the first strand of cable fully extended with a small counterweight, just enough to hold itself and a small payload. From there it's trivial, to add more cable you carry it up the initial cable, and to add more counterweight you have the cable-laying climbers go all the way to the end and become part of the counterweight, and/or send separate climbers to carry up the counterweight.
I think the precision needed for interferometry requires a physical connection between the two telescopes, to hold them in position relative to each other with great accuracy. You can't digitize the images from two telescopes and combine them later for interferometry, you have to make the light gathered by the 2 scopes interfere (hense, interferometry). So basically, you can't pull it off with scopes that are disconnected and too far apart.
Why would they be able to see farther? Even if they launched it out of the solar system, which would cost billions and take many years, it would only be like .01% closer to the nearest star.
You're right, I meant Free, but everyone knew what I meant. The post I was replying to seemed to imply that because the product was easy to copy, it had no value.
Quote:
What is the value of something if it can be copied (reproduced) for (near to) zero cost?
Fact is, after a song, a movie and anything else which can be stored in digital form has been produced, its value is as high as the cost of reproducing and distributing it. Using cheap PCs and broadband internet, this cost is usually pretty much negligible.
Get my point?
Fact is, after a song, a movie and anything else which can be stored in digital form has been produced, its value is as high as the cost of reproducing and distributing it. Using cheap PCs and broadband internet, this cost is usually pretty much negligible.
So you're saying copyright is pointless? How about open source software? Should anyone be able to steal the code and put it in their closed source project, just because it's easy?
There's this little thing called 'gravity' I heard about recently, and wouldn't you know it, it actually affects the course of projectiles! And all this time I thought bullets just went in a straight line until they hit something!
however, the energy would turned into heat by friction with the atmosphere, and the craft would be vaporized
Actually, that's a misconception. The atmosphere is heated by the compression of the air in front of the object, not by friction.
Gotta wonder what this does to his miles per gallon, considering both the weight and the massive alternater load.