dspapo Wrote: ------------------------------------------------------- > can you explain why it would be accelerating > during the entire trip? i’ve never taken a > physics class, and it seems a bit > counter-intuitive to me. i think its because you’d be leaving earth’s gravity and becoming more greatly affected by your target’s gravitational pull.
I assumed you would want to nudge the material into an eliptical (comet-like) orbit that takes it close enough to the earth that you could grab it as it flies by. That would mean that you wouldn’t have to power it very much, although it can still take a very long time to get here (remember that Jupiter goes around the sun in about 13 years). This distance would probably be about 1/3 of Jupiter’s orbit in the the most favorable position, however, it would take a lot of energy to redirect the material away from it’s initial direction (which is the same velocity (approximately) as Jupiter), so you might need to make it take several passes around the sun before it actually gets back to earth. If you do this, then the material would be accelerated by the Sun’s gravity. It’s essentially “falling” towards the Sun from Jupiter, accelerating as it does in the same way that a rock accelerates as it falls to the ground. When it passes Earth, you have to stop it in order to keep it from flying by. The easiest way to do this is probably to try to apply thrust at a right or oblique angle to try to get it to drop into Earth orbit, and then mine it bit by bit while still in orbit, but it would still have to be slowed down considerably, more or less reversing all the acceleration it gained while falling toward the sun. How you could get something from earth orbit to the ground is also tricky. It might be fun to imagine what the fossil record might look like if the dinosaurs had created an intelligent civilization in the last 5000 years of their existence. Perhaps the asteroid that wiped them out was a mining operation gone wrong. 
A continuously powered flight over those distances (Jupiter-Earth) would almost certainly require far more fuel than one could possibly hope to get back by mining the stuff and selling it here on Earth. If you are willing to wait a looong time for this stuff to get here, then it is not quite as difficult to imagine doing, but there’d be an enormous risk premium discounted over many many years, which makes it hard to raise capital for a task like this. Remember, we don’t even have the ability to deflect a small asteroid (say 1 or 2 mile long) heading our way without several decades worth of warning, and even those methods are highly theoretical.
You have to remember that when you’re in orbit, you’re really falling, but you’re falling so fast and at such a steep angle that you actually miss the earth. If you fall too fast, you will be able to get out of orbit. So If you’re coming here after accelerating like crazy to get out of Jupiter’s gravity, you’ll need to slow down a lot otherwise you’d miss earth. You’d probably need to time it so you use the gravity of other planets that lie midway…
rocket fuel and all that crap is so XX century. you need to develop a massive magnetic field to create warps in spacetime and control it to beam stuff down to earth from jupiter momentarily. it has been done before in Lost.
bchadwick Wrote: ------------------------------------------------------- > > It might be fun to imagine what the fossil record > might look like if the dinosaurs had created an > intelligent civilization in the last 5000 years of > their existence. Perhaps the asteroid that wiped > them out was a mining operation gone wrong. > Wouldn’t that be a bitch. We figure out how to economically mine some element in space, shoot it back to earth as a rock the size of Texas, miss the catch, and end up having it crash into earth instead. EDIT: Hey, I didn’t type “Wouldn’t that be a bitch”. I typed “Wouldn’t that be ‘an acceptable term for a female dog’.”
By the way, my comment about the dinosaurs was not an attempt to ridicule anything. If we think that the total of our civilization’s records go back 5000 or perhaps 10000 years, and much of our technological development was in the past 0-200 years, and then remember that the dinosaurs existed for 100-200 million years, then it is conceivable that they might have developed a civilization that does not even show up in the geological record because it has been eroded away. Perhaps they developed spaceflight and went off somewhere else… or blew themselves up with nuclear weapons… what would we actually be able to see today in the geological record. Now, I am not arguing that this is likely, but it is interesting to think that if *we* were to do such a thing, what would others who are either on Earth or passing by Earth 65 million years from now actually see of our civilization. It could very well be that they see that monkey-looking beings that knew how to use stone tools were all over the place for a few million years and then suddenly disappeared, perhaps taking many other species with them.
Anyone else watch the “Ancient Aliens” series on the History Channel? Some of the stuff they show/talk about really makes me wonder, but then they turn around and throw something out there that really makes me question their sanity.
They always have that wierd Mephistopholes-looking guy who talks about all sorts of paranormal stuff, like Nostrodamus, ancient Aliens, etc… He’s like the resident “Ph.D. in wierd stuff studies” guy that they trot out to sound authoritative. Personally, I think we all came from the future. ;-p
Someone with good authority told me that qqqbee traveled to distant planets to start new life.
tj2001 Wrote: ------------------------------------------------------- > As a kid, I always wanted to know everything there > was to know about space, the universe, astronomy, > space research, and all the sci fi stuff that > comes along with it (read: star trek) > > … as an adult, I realize I’m not exactly smart > enough to be an astrophysicist. > > But I am smart enough to be a good investor. > > So here goes: > > We with our space program, NASA and other > organizations similar to NASA; we tend to see > space exploration as an end unto itself. … If > you will, to seek out new frontiers, … to boldly > go where no one has gone before. > > ^This is short sighted. We’re not seeing the > bigger picture: investment. > > We dump billions into NASA for space exploration > without a clear cut goal that would ultimately > help world economies. > > On the otherhand, if there was a greater level of > privatization of the space program and NASA could > work with corporations, there is much profit to be > had and the investment is more than worthwhile. > > And when I say corporations, I specifically refer > to natural resources, mining, prospecting > corporations… We need to invest much much more > to find ways to get people to space faster, > cheaper and have them reasonably travel greater > distances: > > There is an entire solar system enriched with > natural resources for our taking. Mars’s mineral > deposits rival our own as do the hundreds of > thousands of asteroids between Mars and Jupiter. > Titan has oceans of methane. Europa’s waters are > greater than all of Earth’s. Jupiter’s > atmosphere can literally produce enough static > electricity that could be stored as energy to > power some of Earth’s major cities for decades and > decades. > > And let’s not forget that our solar system, though > harsh, is not without its prime pieces of cosmic > real estate. Mars once supported water and > possibly life… with enough technology, it can > again. > > This is an investment opportunity years and years > in the making. We as a society have to decide how > much longer we’re willing to wait to reap the > benefits of our own back yard. Dude I so wanted to be an astrophysicist, but also was not smart/disciplined enough to pull it off when I was younger. Still I read as many physics/space books as I could get my hands on. I still have my Carl Sagan’s Cosmos collection at my parents house and I have my telescope; its not that useful in Manhattan unless I wanna Perv it out one night 
I imagine this post is somewhat in response to the the Discovery. My parents called me up to tell me they saw the discovery launch from their house. I got the chance to see a shuttle launch a couple years ago; its truly amazing and makes you forget just about any problems. While realize the shuttle was a terrible way to get to space (high cost, only LEO), I can’t help feeling an overwhelming sense of sadness and frustration that the shuttle will soon be gone and we have no alternative except awkwardly using Russian rockets to hurl our astronauts to the ISS. tj2001, as you pointed out, NASA has become horribly mismanaged, underfunded and lacks serious goals. IMO its due to continuously changing politics. I really do hope that the private sector does figure out how to carry the torch.
*Double Post
CFABLACKBELT Wrote: ------------------------------------------------------- > tj2001 Wrote: > -------------------------------------------------- > ----- > > As a kid, I always wanted to know everything > there > > was to know about space, the universe, > astronomy, > > space research, and all the sci fi stuff that > > comes along with it (read: star trek) > > > > … as an adult, I realize I’m not exactly > smart > > enough to be an astrophysicist. > > > > But I am smart enough to be a good investor. > > > > So here goes: > > > > We with our space program, NASA and other > > organizations similar to NASA; we tend to see > > space exploration as an end unto itself. … If > > you will, to seek out new frontiers, … to > boldly > > go where no one has gone before. > > > > ^This is short sighted. We’re not seeing the > > bigger picture: investment. > > > > We dump billions into NASA for space > exploration > > without a clear cut goal that would ultimately > > help world economies. > > > > On the otherhand, if there was a greater level > of > > privatization of the space program and NASA > could > > work with corporations, there is much profit to > be > > had and the investment is more than worthwhile. > > > > > And when I say corporations, I specifically > refer > > to natural resources, mining, prospecting > > corporations… We need to invest much much > more > > to find ways to get people to space faster, > > cheaper and have them reasonably travel greater > > distances: > > > > There is an entire solar system enriched with > > natural resources for our taking. Mars’s > mineral > > deposits rival our own as do the hundreds of > > thousands of asteroids between Mars and Jupiter. > > > Titan has oceans of methane. Europa’s waters > are > > greater than all of Earth’s. Jupiter’s > > atmosphere can literally produce enough static > > electricity that could be stored as energy to > > power some of Earth’s major cities for decades > and > > decades. > > > > And let’s not forget that our solar system, > though > > harsh, is not without its prime pieces of > cosmic > > real estate. Mars once supported water and > > possibly life… with enough technology, it can > > again. > > > > This is an investment opportunity years and > years > > in the making. We as a society have to decide > how > > much longer we’re willing to wait to reap the > > benefits of our own back yard. > > Dude I so wanted to be an astrophysicist, but also > was not smart/disciplined enough to pull it off > when I was younger. Still I read as many > physics/space books as I could get my hands on. I > still have my Carl Sagan’s Cosmos collection at my > parents house and I have my telescope; its not > that useful in Manhattan unless I wanna Perv it > out one night > > I imagine this post is somewhat in response to the > the Discovery. My parents called me up to tell me > they saw the discovery launch from their house. I > got the chance to see a shuttle launch a couple > years ago; its truly amazing and makes you forget > just about any problems. While realize the > shuttle was a terrible way to get to space (high > cost, only LEO), I can’t help feeling an > overwhelming sense of sadness and frustration that > the shuttle will soon be gone and we have no > alternative except awkwardly using Russian rockets > to hurl our astronauts to the ISS. tj2001, as you > pointed out, NASA has become horribly mismanaged, > underfunded and lacks serious goals. IMO its due > to continuously changing politics. I really do > hope that the private sector does figure out how > to carry the torch. +1 Carl Sagan has been one of the most inspirational Americans to enchant the minds of American youth of his time and open them up to the wonders of the cosmos. The Pale Blue Dot often gets me teary eyed.
Space mining, I don’t see that as viable until we completely denude our own planet of its resources, which hasn’t happened yet.