Ion Engine

[5614]

i started this a while ago, in the news section, but it never appeared, so i'll try starting it here in the general science section and see what happens, if an admin could move this to the news thread, it would be appreciated.

 

recently a new type of space craft lifted off, it was powered by an ion engine.

 

it works by ionizing atoms or particles and then shooting them out the back of the vechile.

 

whilsts this makes the vechile quite slow at acceleration, it can obtain very fast top speeds and may be the future for long distance travels in space.

 

to reach the moon

takes a normal rocket 3 days

takes this ion powered rocket 14 or 15 months, depending on what website you read!

 

long distance flight

this is where the ion engine takes effect, whilsts there are no figures i can find relating to this, longer distances should take a lot less time in the ion engine space craft than in a conventional space craft.

 

for more information:

http://news.bbc.co.uk/1/hi/sci/tech/3150718.stm

[Douglas]

i started this a while ago' date=' in the news section, but it never appeared, so i'll try starting it here in the general science section and see what happens, if an admin could move this to the news thread, it would be appreciated.[/i']

 

recently a new type of space craft lifted off, it was powered by an ion engine.

 

it works by ionizing atoms or particles and then shooting them out the back of the vechile.

 

whilsts this makes the vechile quite slow at acceleration, it can obtain very fast top speeds and may be the future for long distance travels in space.

 

to reach the moon

takes a normal rocket 3 days

takes this ion powered rocket 14 or 15 months, depending on what website you read!

 

long distance flight

this is where the ion engine takes effect, whilsts there are no figures i can find relating to this, longer distances should take a lot less time in the ion engine space craft than in a conventional space craft.

 

for more information:

http://news.bbc.co.uk/1/hi/sci/tech/3150718.stm

I read an article in Discovery magazine where they talked about methods of propulsion for long distant travel (Alpha Centauri 4 light years). They discounted Anti matter and others. Settled on a hydrogen maser method of propulsion. Since there's very little Hydrogen in space, they needed, perhaps an ion engine to reach a velocity where they could deploy a huge hydrogen collection device, then it would take 7 years to reach ½ the speed of light. The one way trip to alpha centauri would take 14 years.

[5614]

i thought that this thread would have been popular obviously not, to me though, i see this as an important breakthrough which will allow us [humans] to go further into space in realistic time slots.

[SolarFlare]

good thread , this is an important subject

I've been reading various ideas for better and safer space travel and improved designs for the future

 

I'll try to locate some articles that I've seen

[Sayonara]

I didn't think ion engines were new.

 

???

[Dave]

Not really, the idea's been around for over 20 years. I do know there's an ion-powered probe on its way to the moon/has already gotten there. I think the Japanese launched it.

 

Edit: noticed that this has already been mentioned in the link. I'll shut up now

[Martin]

i thought that this thread would have been popular obviously not, to me though, i see this as an important breakthrough which will allow us [humans'] to go further into space in realistic time slots.

 

It is interesting that so far there has not been a lot of enthusiasm shown.

I remember reading NASA publications about ion engines from the 1970s. They actually built them and ran them on the test bed. But they didnt put them into space AFAIK, at least not for main drive applications. That seems to be the news here----ion engines finally in use.

 

I remember I was excited by the concept and found it frustrating that ion propulsion was not being developed and put into use 20 years ago, when they certainly could have.

 

It probably has to wait for future missions where it has a clear advantage.

 

IIRC the good thing about ion drive is that it makes very efficient use of propellant by achieving much higher exhaust velocity than you can with chemical. Just to quote from your link article:

 

"The drive works by accelerating charged xenon gas atoms - ions - out of a chamber at speeds up to 16,000 km/hour. This gives Smart a tiny push - an acceleration of just 0.2 millimetres per second per second - in the opposite direction."

 

That is 4,400 meters per second. I believe that chemical rockets achieve only a few hundred meters per second. Someone here must know more exact figures. Maybe chemical can get 1000 meters per second but I think it is just a few hundred.

 

so 4,400 (if they actually do get that) looks very good: every gram of propellant gives you more impulse, more delta-V.

 

but the bad thing is that the ion drive is very costly in terms of energy.

It takes a lot of electricity.

So there is a committment of mass to either solar cells or to a nuclear power plant of some type (nuclear thermoelectric, say) to make all the electricity.

 

another bad thing is corrosion. IIRC some of the early testbed ion drive units in the 1970s were using mercury as a propellant. that looks good because the mercury ion is heavy and you would put it in an electric field of lots of volts and accelerate it to high speed and get a lot of momentum.

but IIRC the mercury was corrosive.

 

this must be one reason they are now using Xenon. It also is a heavy atom. but probably it is chemically easier to handle.

 

People who think that humans have a destiny to probe the planetary systems of other stars-----or even things as near as our own Oort cloud---should probably be visualizing the use of ion drive with nuclear-generated electricity. Sending an unmanned robot probe to a nearby star would be an example of a mission where nuclear + ion drive might probably prove clearly superior to the existing alternatives.

 

I am the opposite of an expert about this stuff so i hope others who are knowledgeable get in on this thread.

[5614]

i thought that was new from the tone of the article, maybe they invented it a while ago and only recently made it work very well in real life, as well as in tests:

 

The solar-electric engine on the 375-kilogram spacecraft is the mission's key feature.

If the engine can be shown to work well' date=' it is likely to become a standard form of propulsion on many of the inter-planetary explorers built by Esa in the coming years.[/b']

maybe space exploration will advance a bit now... with quicker flights manned missions to mars become a possibility.

 

thinking of outer-solar-system experiments, what kinda distances can data be sent back from, like if we send a probe out of this solar system might be loose contact with it? or is it just a case of the infomation travelling back to us?

[Martin]

as we both can see it doesnt matter when they invented it and it is great that they are putting ion drive into use now

 

I have a suggestion of something you could think about

 

how would you put a space-telescope into a Earth-Sun Lagrange point orbit?

 

this seems to be the coming thing, to put telescopes in their own orbits around the sun, instead of in orbit around the earth

 

it sounds incredible but one of the most celebrated instruments now in operation is WMAP the microwave anisotropy probe taking pictures of the CMB and it is not in orbit around the earth

 

WMAP is in orbit around sun at a distance of roughly some 94 million miles out.

 

WMAP stays in step with the earth and goes around sun in one year, just like we do, but it is a million miles further out from sun than we are

 

 

how would you put a telescope in that kind of orbit? how about spiraling slowly out? and synching up with earth just as you get out to the Lagrange point.

 

what size engine would it take? are there better alternatives?

 

there is someone at SFN who has answers but i forget who it is.

you need to ping someone or somehow catch their attention.

ion drive has cool possibilities

 

In the next 15 years or so people will probably want to put out telescopes that use OPTICAL INTERFEROMETRY to image planets around stars that are like 100 lightyears away----to image earth-size planets.

these interferometry telescopes will probably want to be in their own orbits around sun, instead of going around earth.

 

there are some online documents about these things. we need someone with more knowledge and more familiarity with the sources of information.

 

nearterm optical interferometry telescopes are something one should know about.

 

also keep thinking about the project of sending a probe to a star that is 100 lightyears away and having it radio back data about the star's planets

that is a more longterm project but it is very interesting

[Martin]

thinking of outer-solar-system experiments' date=' what kinda distances can data be sent back from, like if we send a probe out of this solar system might be loose contact with it? or is it just a case of the infomation travelling back to us?[/quote']

 

there are formulas for this

it is not hard

ping swantsont, or look it up

 

evolution has given humans certain instincts that resulted in them getting from Asia to Northamerica like 20,000 years ago and settling all the way down to Chile.

 

Right now in this historical period it is the job of humans to visually spot a planet like the earth and to send a probe to it.

 

the human subjective timescale will adjust to the job.

 

if the radio transmitter is so weak that it can only send one bit per hour then human expectations will adjust to receiving one bit per hour

 

if the propulsion unit is so weak that it can only reach the star in a thousand years then human historical perspective will adjust to waiting a thousand years.

 

if there is a job, and if the job is understood, humans can adapt their minds to the job.

 

but you need to find some SETI site with formulas for the antenna diameter and the wattage and the bit-rate and the distance. I am personally not interested in SETI but the technical problem of how a robot probe can send back data from 50 to 100 lightyears away does seem like an interesting problem.