Science!! Fucking magnets, how do they work?
- Thread starter Flunklesnarkin_sl
- Start date
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Solar sails aren't dumb, it's the only powerless method of propulsion really available to us. Of course acceleration would continue to diminish after as it reaches the edge of out solar system. I suppose we could mount a nuclear reactor on something to give it power for a lot longer.
Furry
🌭🍔🇺🇦✌️SLAVA UKRAINI!✌️🇺🇦🍔🌭
- 21,885
- 28,606
We have some basic ion engines that could provide long term minor acceleration. That said, they're still really slow in terms of galactic speed, just slightly less slow.
Tuco
I got Tuco'd!
- 47,358
- 80,733
Sorry I didn't mean dumb as in, "Based on my knowledge this will not work!" I mean dumb as in it's a fucking sailboat in outer space. I think it could work and I'd love to see some sailboats floating around in space. They might even have a certain majesticism to them.
Big Phoenix
Pronouns: zie/zhem/zer
- 46,372
- 98,475
We just dont build them like that today. Working just fine after traveling for just about 40 fucking years in space.
Cad
scientia potentia est
- 25,426
- 49,042
Without putting a nuclear reactor on it and using a high-wattage ion drive, nothing. Chemical rockets are useless pieces of shit.
But because chemical rockets are so expensive, space travel is limited. Since space travel is so limited, nobody invests in the future propulsion tech. Since nobody invests in propulsion tech, we are stuck with chemical rockets. Because chemical rockets....
Etc
But today, we could put a topaz reactor on a small probe, shoot it up into LEO with 50klbs of propellant, and let it accelerate until it ran out of propellant on the ion drive and it'd probably reach a small fraction of the speed of light.
iannis
Musty Nester
- 31,351
- 17,656
I think solar sailboats are an awesome idea.* Cause you could make them really really really really big. And not only use them as a means of propulsion, but as an advance defense against stray atoms, gas pockets, and micrometeorites.
*Please note the author doesn't know shit about fuck, but it sounds like a good plan to him.
*Please note the author doesn't know shit about fuck, but it sounds like a good plan to him.
McCheese
SW: Sean, CW: Crone, GW: Wizardhawk
- 6,918
- 4,315
If we do this then we should also fill it with smallpox blankets so we can kill any aliens it accidentally encounters.
Skanda
I'm Amod too!
- 6,662
- 4,506
fify
Because not only did he do it before Columbus but he was also a fucking Viking not some pansy Italian.
gogusrl
Molten Core Raider
- 1,362
- 105
It depends how much mess you want to make...
http://en.wikipedia.org/wiki/Project...ar_propulsion)
One interstellar Orion design had a mass of 400,000 tons, 300,000 tons of which was "fuel" i.e. nuclear bombs, and it would take 133 years to reach Alpha Centauri without slowing down. The cost was a mere 0.4 trillion dollars back in the 1960s.
*edit*
The inspiration for this was supposedly the Pascal B nuclear test when a 2,000 lb piece of steel armour was blasted off the end of a test shaft and travelled at an estimated 41 miles per second.
"After the event, Dr. Robert R. Brownlee described the best estimate of the cover's speed from the photographic evidence as "going like a bat out of hell""
http://en.wikipedia.org/wiki/Pascal-B
Eomer
Trakanon Raider
- 5,472
- 272
A few people mentioned it already, but ion drives are certainly an option now.
Well, most space probes already are nuclear powered by radioisotope thermoelectric generators (I copied that from Wikipedia!). But I don't know those can generate enough power to work with an ion drive. Infoz:http://en.wikipedia.org/wiki/Voyager_program#PowerThe Ancient_sl said:
Those suckers are still producing over 50% of the power they did 40 years ago. That's impressive as hell.
However it would appear that most ion drives are in the 10's to 100's of kW. So a couple of orders of magnitude more than RTG's seem to produce. But you could trickle charge a battery system and fire the ion engine in bursts, as well.
The important thing to remember is that you're always accelerating with an Ion drive. It doesn't matter that it is accelerating you at 1/1000 gravity, after a year of that you're at 69,2742 mph if you start from zero (you're not starting from zero). Constant acceleration makes a big difference.
Recent article:
http://www.gizmag.com/improved-ion-e...ifetime/26323/
Recent article:
http://www.gizmag.com/improved-ion-e...ifetime/26323/
Its a shame really how far away we are to actually be able to explore anything but the moon and maybe mars in the next 50 years.
I don't think he'd mind me posting this. From Robert Heinlein's Expanded Universe. Sorry for the formatting.
Ah, but not explored by men - and the distances are so great. Surely they are. . . by free - fall orbits, which is all that we have been using. But there are numerous proposals (and not all ours!) for constant - boost ships, proposals that require R&D on present art only - no breakthroughs.
Reach for your pocket calculator and figure how long it would take to make a trip to Mars and back if your ship could boost at one - tenth gee. We will omit some trivia by making it from parking orbit to parking orbit, use straight - line trajectories, and ignore the Sun's field - we'll be going uphill to Mars, downhill to Earth; what we lose on the roundabouts we win on the shys.
These casual assumptions would cause Dan Alderson, ballistician at Jet Propulsion Laboratory, to faint. But after he comes out of his faint he would agree that our answers would be of correct close order of magnitude - and all I'm trying to prove is that even a slight constant boost makes an enormous difference in touring the Solar System. (Late in the 21st century we'll offer the Economy Tour: Ten Planets in Ten Days.)
There are an unlimited number of distances between rather wide parameters for an Earth - Mars Earth trip but we will select one that is nearly minimum (it's cheating to wait in orbit at Mars for about a year in order take the shortest trip each way.. . and unthinkable to wait years for the closest approach). We'll do this Space Patrol style: There's Mars, here we are at L - 5; let's scoot over, swing around Mars, and come straight home. Just for drill.
Conditions: Earth - surface gravity (one "gee") is an acceleration of 32.2 feet per second squared, or 980.7 centimeters per second squared. Mars is in or near op
position (Mars is rising as Sun is setting). We will assume that the round trip is 120,000,000 miles. If we were willing to wait for closest approach we could trim that to less than 70,000,000 miles .. . but we might have to wait as long as 17 years. So we'll take a common or garden variety opposition - one every 26 months - for which the distance to Mars is about 50 - to 60,000,000 miles and never over 64 million.
(With Mars in conjunction on the far side of the Sun, we could take the scenic route of over 500 million miles - how much over depends on how easily you sunburn. I suggest a minimum of 700 million miles.)
You now have all necessary data to figure the time it takes to travel Earth - Mars - Earth in a constant - boost ship - any constant - boost ship - when Mars is at opposition. (If you insist on the scenic route, you can't treat the trajectory approximations as straight lines and you can't treat space as flat but a bit uphill. You'll need Alderson or his equal and a big computer, not a pocket calculator; the equations are very hairy and sometimes shoot back.)
But us two space cadets are doing this by eyeballing it, using Tennessee windage, an aerospace almanac, a Mickey Mouse watch, and an SR - 50 Pop discarded years ago.
We need just one equation: Velocity equals acceleration times elapsed time: v = at
This tells us that our average speed is 1/2at - and from that we know that the distance achieved is the average speed times the elapsed time: d = 1/2at2
If you don't believe me, check any physics text, encyclopedia, or nineteen other sorts of reference books - and I did that derivation without cracking a book but now I'm going to stop and find out whether I've goofed - I've had years of practice in goofing. (Later - seems okay.)
Just two things to remember: 1) This is a 4 - pieces trip - boost to midpoint, flip over and boost to brake; then do the same thing coming home. Treat all four
legs as being equal or 30,000,000 miles, so figure one of them and multiply by four (Dan, stop frowning; this is an approximation . . . done with a Mickey Mouse watch.)
2) You must keep your units straight. If you start with centimeters, you are stuck with centimeters; if you start with feet, you are stuck with feet. So we have 1/4 of the trip equals 5280 x 30,000,000 = 1.584 x 1011 feet, or 4.827 x 1012 centimeters.
One last bit: Since it is elapsed time we are after, we will rearrange that equation (d = 1/2at2) so that you can get the answer in one operation on your trusty but - outdated pocket calculator. . . or even on a slide rule, as those four - significant - figures data are mere swank; I've used so many approximations and ignored so many minor variables that I'll be happy to get answers correct to two significant figures.
- = t2 This gives us: t = Vd/1/2a
V2a
d is 30,000,000 miles expressed in feet, or 158,400,000,000. Set that into your pocket calculator. Divide it by one half of one tenth of gee, or 1.61. Push the square root button. Multiply by 4. You now have the elapsed time of the round trip expressed in seconds so divide by 3600 and you have it in hours, and divide that by 24 and you have it in days.
At this point you are supposed to be astonished and to start looking for the mistake. While you are looking, I'm going to slide out to the refrigerator.
There is no mistake. Work it again, this time in metric. Find a reference book and check the equation. You will find the answer elsewhere in this book but don't look for it yet; we'll try some other trips you may take by 2000 A.D. if you speak Japanese or German - or even English if Proxmire and his ilk fail of reelection.
Same trip, worked the same way, but at only one
percent of gee. At that boost I would weigh less than my shoes weigh here in my study.
Hmmph! Looks as if one answer or the other must be wrong.
Bear with me. This time we'll work it at a full gee, the acceleration you experience lying in bed, asleep. (See Einstein's 1905 paper.)
(Preposterous. All three answers must be wrong.)
Please stick with me a little longer. Let's run all three problems for a round trip to Pluto - in 2006 A.D., give or take a year. Why 2006? Because today Pluto has ducked inside the orbit of Neptune and won't reach perihelion until 1989 - and I want it to be a bit farther away; I've got a rabbit stashed in the hat.
Pluto ducks outside again in 2003 and by 2006 it will be (give or take a few million miles) 31.6 A.U. from the Sun, figuring an A.U. at 92,900,000 miles or 14,950,000,000,000 centimeters as we'll work this both ways, MKS and English units. (All right, all right - 1.495 x 1013 centimeters; it gets dull here at this typewriter.)
Now work it all three ways, a round trip of 63.2 A.U. at a constant boost of one gravity, one tenth gravity, and one hundredth of a gee - and we'll dedicate this to Clyde Tombaugh, the only living man to discover a new planet - through months of tedious and painstaking examination of many thousands of films.
Some think that Pluto was once a satellite and its small size makes this possible. But it is not a satellite today. It is both far too big and hundreds of millions of miles out of position to be an asteroid. It can't be a comet. So it's a planet - or something so exotic as to be still more of a prize.
Its size made it hard to find and thus still more of an achievement. But Tombaugh continued the search for seventeen weary years and many millions more films. If there is an Earth - size planet out there, it is at least three times as distant as Pluto, and a gas giant would have to be six times as far. Negative data win
no prizes but they are the bedrock of science.
Until James W. Christy on 22 June 1978 discovered Pluto's satellite, Charon, it was possible for us romantics to entertain the happy thought that Pluto was loaded with valuable heavy metals; the best estimate of its density made this plausible. But the mass of a planet with a satellite can be calculated quite easily and accurately, and from that, its density.
The new figure was much too low, only half again as heavy as water. Methane snow? Perhaps.
So once again a lovely theory is demolished by an awkward fact.
Nevertheless Pluto remains a most mysterious and most intriguing heavenly body. A planet the size and mass of Mars might not be too much use to us out there . . . but think of it as a fuel dump. Many stories and many nonfictional projections speak of using the gas giants and/or the rings of Saturn as sources of fuel. But if Pluto is methane ice or water ice or frozen hydrogen or all three, as a source of fuel - conventional, or fusion, or even reaction mass - Pluto has one supremely important advantage over the gas giants: Pluto is not at the bottom of a horridly deep gravity well.
Finished calculating? Good. Please turn to page 368 and see why I wanted our trip to Pluto to be a distance of 31.6 A.U. - plus other goodies, perhaps.
Ah, but not explored by men - and the distances are so great. Surely they are. . . by free - fall orbits, which is all that we have been using. But there are numerous proposals (and not all ours!) for constant - boost ships, proposals that require R&D on present art only - no breakthroughs.
Reach for your pocket calculator and figure how long it would take to make a trip to Mars and back if your ship could boost at one - tenth gee. We will omit some trivia by making it from parking orbit to parking orbit, use straight - line trajectories, and ignore the Sun's field - we'll be going uphill to Mars, downhill to Earth; what we lose on the roundabouts we win on the shys.
These casual assumptions would cause Dan Alderson, ballistician at Jet Propulsion Laboratory, to faint. But after he comes out of his faint he would agree that our answers would be of correct close order of magnitude - and all I'm trying to prove is that even a slight constant boost makes an enormous difference in touring the Solar System. (Late in the 21st century we'll offer the Economy Tour: Ten Planets in Ten Days.)
There are an unlimited number of distances between rather wide parameters for an Earth - Mars Earth trip but we will select one that is nearly minimum (it's cheating to wait in orbit at Mars for about a year in order take the shortest trip each way.. . and unthinkable to wait years for the closest approach). We'll do this Space Patrol style: There's Mars, here we are at L - 5; let's scoot over, swing around Mars, and come straight home. Just for drill.
Conditions: Earth - surface gravity (one "gee") is an acceleration of 32.2 feet per second squared, or 980.7 centimeters per second squared. Mars is in or near op
position (Mars is rising as Sun is setting). We will assume that the round trip is 120,000,000 miles. If we were willing to wait for closest approach we could trim that to less than 70,000,000 miles .. . but we might have to wait as long as 17 years. So we'll take a common or garden variety opposition - one every 26 months - for which the distance to Mars is about 50 - to 60,000,000 miles and never over 64 million.
(With Mars in conjunction on the far side of the Sun, we could take the scenic route of over 500 million miles - how much over depends on how easily you sunburn. I suggest a minimum of 700 million miles.)
You now have all necessary data to figure the time it takes to travel Earth - Mars - Earth in a constant - boost ship - any constant - boost ship - when Mars is at opposition. (If you insist on the scenic route, you can't treat the trajectory approximations as straight lines and you can't treat space as flat but a bit uphill. You'll need Alderson or his equal and a big computer, not a pocket calculator; the equations are very hairy and sometimes shoot back.)
But us two space cadets are doing this by eyeballing it, using Tennessee windage, an aerospace almanac, a Mickey Mouse watch, and an SR - 50 Pop discarded years ago.
We need just one equation: Velocity equals acceleration times elapsed time: v = at
This tells us that our average speed is 1/2at - and from that we know that the distance achieved is the average speed times the elapsed time: d = 1/2at2
If you don't believe me, check any physics text, encyclopedia, or nineteen other sorts of reference books - and I did that derivation without cracking a book but now I'm going to stop and find out whether I've goofed - I've had years of practice in goofing. (Later - seems okay.)
Just two things to remember: 1) This is a 4 - pieces trip - boost to midpoint, flip over and boost to brake; then do the same thing coming home. Treat all four
legs as being equal or 30,000,000 miles, so figure one of them and multiply by four (Dan, stop frowning; this is an approximation . . . done with a Mickey Mouse watch.)
2) You must keep your units straight. If you start with centimeters, you are stuck with centimeters; if you start with feet, you are stuck with feet. So we have 1/4 of the trip equals 5280 x 30,000,000 = 1.584 x 1011 feet, or 4.827 x 1012 centimeters.
One last bit: Since it is elapsed time we are after, we will rearrange that equation (d = 1/2at2) so that you can get the answer in one operation on your trusty but - outdated pocket calculator. . . or even on a slide rule, as those four - significant - figures data are mere swank; I've used so many approximations and ignored so many minor variables that I'll be happy to get answers correct to two significant figures.
- = t2 This gives us: t = Vd/1/2a
V2a
d is 30,000,000 miles expressed in feet, or 158,400,000,000. Set that into your pocket calculator. Divide it by one half of one tenth of gee, or 1.61. Push the square root button. Multiply by 4. You now have the elapsed time of the round trip expressed in seconds so divide by 3600 and you have it in hours, and divide that by 24 and you have it in days.
At this point you are supposed to be astonished and to start looking for the mistake. While you are looking, I'm going to slide out to the refrigerator.
There is no mistake. Work it again, this time in metric. Find a reference book and check the equation. You will find the answer elsewhere in this book but don't look for it yet; we'll try some other trips you may take by 2000 A.D. if you speak Japanese or German - or even English if Proxmire and his ilk fail of reelection.
Same trip, worked the same way, but at only one
percent of gee. At that boost I would weigh less than my shoes weigh here in my study.
Hmmph! Looks as if one answer or the other must be wrong.
Bear with me. This time we'll work it at a full gee, the acceleration you experience lying in bed, asleep. (See Einstein's 1905 paper.)
(Preposterous. All three answers must be wrong.)
Please stick with me a little longer. Let's run all three problems for a round trip to Pluto - in 2006 A.D., give or take a year. Why 2006? Because today Pluto has ducked inside the orbit of Neptune and won't reach perihelion until 1989 - and I want it to be a bit farther away; I've got a rabbit stashed in the hat.
Pluto ducks outside again in 2003 and by 2006 it will be (give or take a few million miles) 31.6 A.U. from the Sun, figuring an A.U. at 92,900,000 miles or 14,950,000,000,000 centimeters as we'll work this both ways, MKS and English units. (All right, all right - 1.495 x 1013 centimeters; it gets dull here at this typewriter.)
Now work it all three ways, a round trip of 63.2 A.U. at a constant boost of one gravity, one tenth gravity, and one hundredth of a gee - and we'll dedicate this to Clyde Tombaugh, the only living man to discover a new planet - through months of tedious and painstaking examination of many thousands of films.
Some think that Pluto was once a satellite and its small size makes this possible. But it is not a satellite today. It is both far too big and hundreds of millions of miles out of position to be an asteroid. It can't be a comet. So it's a planet - or something so exotic as to be still more of a prize.
Its size made it hard to find and thus still more of an achievement. But Tombaugh continued the search for seventeen weary years and many millions more films. If there is an Earth - size planet out there, it is at least three times as distant as Pluto, and a gas giant would have to be six times as far. Negative data win
no prizes but they are the bedrock of science.
Until James W. Christy on 22 June 1978 discovered Pluto's satellite, Charon, it was possible for us romantics to entertain the happy thought that Pluto was loaded with valuable heavy metals; the best estimate of its density made this plausible. But the mass of a planet with a satellite can be calculated quite easily and accurately, and from that, its density.
The new figure was much too low, only half again as heavy as water. Methane snow? Perhaps.
So once again a lovely theory is demolished by an awkward fact.
Nevertheless Pluto remains a most mysterious and most intriguing heavenly body. A planet the size and mass of Mars might not be too much use to us out there . . . but think of it as a fuel dump. Many stories and many nonfictional projections speak of using the gas giants and/or the rings of Saturn as sources of fuel. But if Pluto is methane ice or water ice or frozen hydrogen or all three, as a source of fuel - conventional, or fusion, or even reaction mass - Pluto has one supremely important advantage over the gas giants: Pluto is not at the bottom of a horridly deep gravity well.
Finished calculating? Good. Please turn to page 368 and see why I wanted our trip to Pluto to be a distance of 31.6 A.U. - plus other goodies, perhaps.
N.B.: All trips are Earth parking orbit to Earth parking orbit without stopping at the target planet (Mars or Pluto). I assume that Hot Pilot Tom Corbett will handle his gravity - well maneuvers at Mars and at Pluto so as not to waste mass - energy - but that's his problem. Now about that assumption of "flat space" only slightly uphill: The Sun has a fantastically deep gravity well; its "surface" gravity is 28 times as great as ours and its escape speed is 55 + times as great - but at the distance of Earth's orbit that grasp has attenuated to about one thousandth of a gee, and at Pluto at 31.6 A.U. it has dropped off to a gnat's whisker, one millionth of gee.
(No wonder it takes 2 1/2 centuries to swing around the Sun. By the way, some astronomers seem positively gleeful that today Pluto is not the planet farthest from the Sun. The facts: Pluto spends nine - tenths of its time outside Neptune's orbit, and it averages being 875,000,000 miles farther out than Neptune - and at maximum is nearly 2 billion miles beyond Neptune's orbit (1.79 x 10 miles) friends, that's more than distance from here to Uranus, nearly four times as far as from here to Jupiter. When Pluto is out there - l 865 or 2114 A.D. - it takes light 6 hours and 50 minutes to reach it. Pluto - the Winnuh and still Champeen! Sour grapes is just as common among astronomers as it is in school yards.)
ROUND TRIP BOOST COMPARISON OF ELAPSED TIME
Earth - Mars - Earth - Earth - Pluto - Earth
@1 gee 4.59 days vs. 4.59 weeks
@ 1/10 gee 14.5 days vs. 14.5 weeks
@ 1/100 gee 45.9 days vs. 45.9 weeks
@ 1/1000 gee 145 days vs. 145 weeks
- and the rabbit is out of the hat. You will have noticed that the elapsed - time figures are exactly the same in both columns, but in days for Mars, weeks for Pluto - i.e., with constant - boost ships of any sort Pluto is only 7 times as far away for these conditions as is Mars even though in miles Pluto is about 50 times as far away.
Willing to settle today for a constant boost on the close order of magnitude of 1/1000 gee, we can start the project later this afternoon, as there are several known ways of building constant - boost jobs with that tiny acceleration - even light - sail ships.
I prefer to talk about light - sail ships (or, rather, ships that sail in the "Solar wind") because those last illustrations I added (1/1000 gee) show that we have the entire Solar System available to us right now; it is not necessary to wait for the year 2000 and new breakthroughs.
Ten weeks to Mars . . . a round trip to Pluto at 31.6 A.U. in 2 years and 9 months. . . or a round trip to Pluto's aphelion, the most remote spot we know of in the Solar System (other than the winter home of the comets).
Ten weeks - it took the Pilgrims in the Mayflower nine weeks and three days to cross the Atlantic.
Two years and nine months - that was a normal commercial voyage for a China clipper sailing out of Boston in the last century . . . and the canny Yankee merchants got rich on it.
Three years and twenty - five weeks is excessive for the China trade in the 19th century.. . but no one will ever take that long trip to Pluto because Pluto does not reach aphelion until 2113 and by then we'll have ships that can get out there (constant boost with turnover near midpoint) in three weeks.
Please note that England, Holland, Spain, and Portugal all created worldwide empires with ships that took as long to get anywhere and back as would a 1/1000 - gee spaceship. On the high seas or in space it is not distance that counts but time. The magnificent accomplishments of our astronauts up to now were made in free fall and are therefore analogous to floating down the Mississippi on a raft. But even the tiniest constant boost turns sailing the Solar System into a money - making commercial venture
(No wonder it takes 2 1/2 centuries to swing around the Sun. By the way, some astronomers seem positively gleeful that today Pluto is not the planet farthest from the Sun. The facts: Pluto spends nine - tenths of its time outside Neptune's orbit, and it averages being 875,000,000 miles farther out than Neptune - and at maximum is nearly 2 billion miles beyond Neptune's orbit (1.79 x 10 miles) friends, that's more than distance from here to Uranus, nearly four times as far as from here to Jupiter. When Pluto is out there - l 865 or 2114 A.D. - it takes light 6 hours and 50 minutes to reach it. Pluto - the Winnuh and still Champeen! Sour grapes is just as common among astronomers as it is in school yards.)
ROUND TRIP BOOST COMPARISON OF ELAPSED TIME
Earth - Mars - Earth - Earth - Pluto - Earth
@1 gee 4.59 days vs. 4.59 weeks
@ 1/10 gee 14.5 days vs. 14.5 weeks
@ 1/100 gee 45.9 days vs. 45.9 weeks
@ 1/1000 gee 145 days vs. 145 weeks
- and the rabbit is out of the hat. You will have noticed that the elapsed - time figures are exactly the same in both columns, but in days for Mars, weeks for Pluto - i.e., with constant - boost ships of any sort Pluto is only 7 times as far away for these conditions as is Mars even though in miles Pluto is about 50 times as far away.
Willing to settle today for a constant boost on the close order of magnitude of 1/1000 gee, we can start the project later this afternoon, as there are several known ways of building constant - boost jobs with that tiny acceleration - even light - sail ships.
I prefer to talk about light - sail ships (or, rather, ships that sail in the "Solar wind") because those last illustrations I added (1/1000 gee) show that we have the entire Solar System available to us right now; it is not necessary to wait for the year 2000 and new breakthroughs.
Ten weeks to Mars . . . a round trip to Pluto at 31.6 A.U. in 2 years and 9 months. . . or a round trip to Pluto's aphelion, the most remote spot we know of in the Solar System (other than the winter home of the comets).
Ten weeks - it took the Pilgrims in the Mayflower nine weeks and three days to cross the Atlantic.
Two years and nine months - that was a normal commercial voyage for a China clipper sailing out of Boston in the last century . . . and the canny Yankee merchants got rich on it.
Three years and twenty - five weeks is excessive for the China trade in the 19th century.. . but no one will ever take that long trip to Pluto because Pluto does not reach aphelion until 2113 and by then we'll have ships that can get out there (constant boost with turnover near midpoint) in three weeks.
Please note that England, Holland, Spain, and Portugal all created worldwide empires with ships that took as long to get anywhere and back as would a 1/1000 - gee spaceship. On the high seas or in space it is not distance that counts but time. The magnificent accomplishments of our astronauts up to now were made in free fall and are therefore analogous to floating down the Mississippi on a raft. But even the tiniest constant boost turns sailing the Solar System into a money - making commercial venture
That's an interesting idea. Are Ion drives roughly as efficient when bursted vs constant?
Eomer
Trakanon Raider
- 5,472
- 272
Yeah, I really have no idea if they need to warm up or some shit. Nor if it's possible to make a super small ion drive that could run on 500 watts instead of 10 kW or whatever.
Looks like they're thinking of giving it a shot on the ISS:http://en.wikipedia.org/wiki/Ion_thruster
Looks like they're thinking of giving it a shot on the ISS:http://en.wikipedia.org/wiki/Ion_thruster
Neato.
Ideally, you run an Ion engine constantly at the "optimal" output. Think about it like driving on the highway at 55 (or whatever the most fuel efficient speed is these days). You can gun your accelerator and maybe get there faster, but you'll burn more fuel. We slam the gas pedal in our cars because we don't need the entire tank to get where we're going. In space, the goal is to maximize the fuel tank because you need every single drop of fuel. That's why constant thrust at optimal levels is so desirable. The bursts can work and the bursts can be efficient, but it won't provide the same amount of thrust at the same efficiency as constantly burning at a optimal output.
The VASIMR is exciting because you can vary the output from low levels of high efficiency thrust to less efficient, but faster acting bursts of force for a more immediate effect. This lets a craft get up to speed faster, but less efficienctly, but it can then switch to optimal outputs for the long-haul. This allows a balance between better acceleration and more efficient thrust. In short, the VASIMR let's the operator plan out the trip so that he gets there in a fast, yet still efficient, way with the arrival time determined by how quickly they need to get there versus how much they need to save fuel.
The VASIMR is exciting because you can vary the output from low levels of high efficiency thrust to less efficient, but faster acting bursts of force for a more immediate effect. This lets a craft get up to speed faster, but less efficienctly, but it can then switch to optimal outputs for the long-haul. This allows a balance between better acceleration and more efficient thrust. In short, the VASIMR let's the operator plan out the trip so that he gets there in a fast, yet still efficient, way with the arrival time determined by how quickly they need to get there versus how much they need to save fuel.