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Ion Engine Propels Probe to Moon
lenin writes "The BBC is reporting that Europe's first moon mission, SMART-1, appears to be a success thus far. It also talks about the low-cost technology being used and the charged xenon (ion) propulsion system. Can TIE-fighters be far off?"
Sure the Ion drive is a really neat addition, but it's soooo slooooow. It's going to take them 15 MONTHS to get there! And the payload isn't really greater at all. It takes longer to get any large loads going. The US space program got people to the moon and back in what...2 weeks? It may be slightly more economical, but it just doesn't seem practical.
Hopefully they can perfect the ion drive, however through this to increase the speed and payload capacity. Then we might have something really cool... (until the anti-matter reactor comes online...)
Check out this page for some nifty things you can build that may work on ion-propulsion. I thought it was a hoax at first, but my friend convinced me to build it in high-school, and the thing really did work. Of course, the efficiency was terrible. We were using an old monitor as a 20,000 volt power source, so power dissipation was probably pretty high. That was enough to lift the 2 gram device and 1 gram of payload.
A deep unwavering belief is a sure sign you're missing something...
The point of ion drive is that it has waaaay higher efficiency than chemical rockets. Momentum is mass times velocity, so by pumping up the velocity you can correspondingly reduce the mass. That's what Ion drive does. It spits out atoms at ridiculous speeds.
Consider a chemical rocket. It very quickly gets you up to speed, but after that you just coast.
Now consider a drive that has, say, only 1/100th as much acceleration, but can run 10000 times longer. It'll take a long time to use up that fuel, but when you're done you will be going 100 times faster than the chemical rocket.
Obviously Ion drive is only useful once you're already in orbit, but if time is not an issue it's hard to beat.
You're russian history is incorrect. They have had several mishaps. The ones that I can think of off the top of my head are Soyuz 1 and Soyuz 11. They have probably had somewhere between 150-200 manned launches. We'll hav change your definition of "launch mishap" to "the rocket went up but the people didn't come down alive".
We have had two accidents in our space program (3 if you count Apollo I, but in the above definition, it doesn't count)
The Russians do more launches than we do. In the past, they've done more manned launches than we did. Since the past 5 years, I'd say that we've probably done about the same number of manned launches.
This one is more reputable, I believe credited to Arthur C. Clarke.
...
It was a short story about an Earth-to-Moon (orbit-to-orbit) space race, in the spirit of the Kremer prize. The spacecraft were propelled by ion engines, which were energized by Whimshurst-type machines, which were powered by
bicycles.
The racers pedaled their way to the moon, the pedals effectively powering the ion engines that drove them. The race took several days, with the right stuff added in for absurd athletics, rest breaks, minimal life-support, race security, etc.
No doubt someone here will do the math that I never bothered trying to do. One of these days, maybe I will.
The living have better things to do than to continue hating the dead.
There will be no TIE fighters until we have friction in space. To be able to turn like an airplane in an atmosphere you need something to react against.
AFAIK, space isn't a perfect vacuum, there is matter in space, just that it's concentrations are extraordinarily low. You'd need either a very large control surface, or some method of increasing friction over what limited matter there is. Why do we use brake pads on a car and not say, bars of moist Ivory? Same reason.
Also, there is also free energy in space...particularly in a solar system. I'm not sure if light energy is believed to be particulate this week, but is it possible that photons or other forms of high frequenty energy could be used as a repuslive force? There's still quite a bit we don't understand about this stuff, and though at this point it's still probably the rhelm of science fiction, It's not impossible. Remember, there are no fictionless surfaces, no perfect vacuums, no perfect superconductors, only asymptoticly approaching approximations.
-Chris
PS - I apologize in advance for the above average number of typos and possible flaws in knowledge and logic....I'm on an iMac today ;-)
--an unbreakable toy is useful for breaking other toys--
if your '71 chevy truck is slow, you just put in a bigger engine right?! so how about a bigger ION drive. and a small nucleur reactor.
i suppose you do lose some efficiency by carrying your own fuel, but nuclear power is far more efficient than solar power right now.
with larger ION drives, or more small ION drives, and enough power from the reactor, this may be able to compete with a rocket engine for inter-solarsystem travel.
but then again, id rather have laser,mazer, or phaser cannons. I'll travel really really slowly if I have a really big gun!
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another advantage would be less vibration during accelleration. Imageing sending a team to Alpha Centauri using standard rockets. They would have to burn for 3 solid months to accellerate and the same to decellerate. 3 months is a long time to be strapped to a chair.
this solves the lack of gravity problem as well. Just accellerate at a rate the would be near 1G or at some acceptable level of force, then spin the ship around and do the same thing for decelleration. This way you would have artificial gravity for a good portion of the trip. I can't imagine the side effects of a couple of years is zero G, and what happens when the team trys to go to the plannet with no muscles built up for planetside life.
Alpha Centauri is something like 5,644,944,000 kilometers away, this is most likely a 5-10 year trip. Yes, artificial gravity would be good.
Also, the waste material from the reactor could be used as the actualy propellant(maybee, IANORS(I am Not a Rocket Scientist) and then you wouldn't have to store it, you could just eject it out the back of the craft.
it's a limit because the maximum velocity for a space craft is the velocity with which it ejects its fuel. Ion engines are faster than chemical engines because the xenon is highly accelerated. The acceleration of the ion propelled space craft is (currently) low, because the thrust of an engine is proportional to the mass of expelled fuel. When ion engines become mature, it will be possible to expel more ions and then you wont need to have a one year acceleration phase before the actual mission can start. So the fastest engine imaginable with current physics would be some giant lamp using photons as fuel. If you accelerate infinitely long you would get light speed. (Obviuosly you can never reach maximum velocity.)
the most sexp i get is my paren-mode.
In more than 35 years of spaceflight the Russians have had something like 4 fatalities, and 3 (?) accidents (including one where the crew survived a booster failure in mid-flight - the stage didn't separate). In comparison to the U.S. record this is remarkably good. They have also flown more people for longer periods of time.
Since the past 5 years, I'd say that we've probably done about the same number of manned launches.
The same number of launches as the U.S., with a total budget of something like 200 million dollars, a factor of 30 less money. That's pretty impressive. The simple turth is that the U.S. is a second-rate space power.
Human genome = 3 billion base pairs = 6 GBit. Windows + Office = 20 Gbit. Which is more impressive?
It may help to think of any rocket-type (and ion, too) propulsion based system like this:
Basically, the center of mass of a fueled up rocket does not change. If you had a rocket at a dead stop and started a burn, you'd throw as much stuff behind you as your displacement was forward. Hence in a simplified 1D rocket model (which is actually pretty close to correct, diffusion is actually pretty minimal) your center of mass never moves.
Arguably, you could say this means that the entire rocket array (fuel and all) never actually moves: just spreads itself out, with the useful "stuff" at one end of the displacement.
My favorite proposal from the near past was the magnetic bubble. Create a large static magnetic field - a simple dipole will do- in space, and then fill it up with plasma. The plasma causes it to expand greatly in size, which is important because the dipole field decays as r^-3. It would act much like the Earth's own magnetosphere with a shock upwind and a long tail. But unlike at Earth, this magnetic bubble can be oriented in any direction. It has been compared to a balloon in operation.
"I'm so moist I'm sticking to the leather." -Kermit the Frog on The Late Late Show
Yes, I damned well belive the Moon landings happened. I've done chemical analysis on the rocks; I've met some of the astronauts; my best friends dad helped build the LEM at Grumman. So yeah, they happened.
I'm not sure what annoys me more: idiots like you who don't think it ever happened, or the idiots in the White House, Congress and the public who didn't think it's important enough to keep funding.
I guess we're living in a society where our greatest achievements lie behind us, rather than ahead of us. In that situation I shouldn't be surprised that there are fools like you who try to make themselves feel better by claiming the achievements of the past never happened.
Human genome = 3 billion base pairs = 6 GBit. Windows + Office = 20 Gbit. Which is more impressive?