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A Breakthrough in Ion Thrusters?

W

WeAreStarStuff

Member
Since the OP did a terrible summary.

"We have shown that X3 can operate at over 100 kW of power," said Alec Gallimore, who is leading the project, in an interview with Space.com. "It operated at a huge range of power from 5 kW to 102 kW, with electrical current of up to 260 amperes. It generated 5.4 Newtons of thrust, which is the highest level of thrust achieved by any plasma thruster to date," added Gallimore, who is dean of engineering at the University of Michigan. The previous record was 3.3 Newtons, according to the school.
Click to expand...
 
S

Steel

Banned
That's a big increase relatively, but it goes from a paperweight's worth of force to a full water bottle's worth of force. It's useful for long journeys but you're not getting anywhere particularly fast with it.
 
J

jellies_two

Member
It sounds like they built one much heavier thruster that is a combination of several original ones:

"We figured out that instead of having one channel of plasma, where the plasma generated is exhausted from the thruster and produces thrust, we would have multiple channels in the same thruster," Gallimore said. "We call it a nested channel.""
 
blu

blu

Wants the largest console games publisher to avoid Nintendo's platforms.
Steel said:
That's a big increase relatively, but it goes from a paperweight's worth of force to a full water bottle's worth of force. It's useful for long journeys but you're not getting anywhere particularly fast with it.
Click to expand...
You'd be getting to Mars particularly fast with it.
 
Z

zeemumu

Member
jellies_two said:
It sounds like they built one much heavier thruster that is a combination of several original ones:

"We figured out that instead of having one channel of plasma, where the plasma generated is exhausted from the thruster and produces thrust, we would have multiple channels in the same thruster," Gallimore said. "We call it a nested channel.""
Click to expand...

But it's morning in the Congo!
 
F

Fenderputty

Banned
blu said:
You'd be getting to Mars particularly fast with it.
Click to expand...

Do they plan to slow craft down using the ion drive? In that instance you would have to start slowing half way to any location. If you're not going stupid fast I would imagine slowing down could be done by more conventional thrust techniques????
 
D

danthefan

Member
Steel said:
That's a big increase relatively, but it goes from a paperweight's worth of force to a full water bottle's worth of force. It's useful for long journeys but you're not getting anywhere particularly fast with it.
Click to expand...

You're not going to get into orbit with it, but once you're in space they can propel you to huge velocities and they only need a tiny mass of fuel compared to rocket engines. Again, once in orbit, they'll be much faster to get to Mars than any other method we have.
 
blu

blu

Wants the largest console games publisher to avoid Nintendo's platforms.
Prez said:
How long would it take?
Click to expand...
We'd still need to get into the MW range (kW so far), but here's an estimate.

Fenderputty said:
Do they plan to slow craft down using the ion drive? In that instance you would have to start slowing half way to any location. If you're not going stupid fast I would imagine slowing down could be done by more conventional thrust techniques????
Click to expand...
Stopping is not that hard when you have a planetary body with an atmosphere at the destination.
 
H

HStallion

Now what's the next step in your master plan?
Steel said:
That's a big increase relatively, but it goes from a paperweight's worth of force to a full water bottle's worth of force. It's useful for long journeys but you're not getting anywhere particularly fast with it.
Click to expand...

In space there is nothing to slow you down so even a small amount of thrust can build and build over distances to travel at great speeds. Of course this needs to take into account slowing down as the ship gets near to its destination but still this is already a pretty big step up.
 
S

Steel

Banned
danthefan said:
You're not going to get into orbit with it, but once you're in space they can propel you to huge velocities and they only need a tiny mass of fuel compared to rocket engines. Again, once in orbit, they'll be much faster to get to Mars than any other method we have.
Click to expand...

blu said:
You'd be getting to Mars particularly fast with it.
Click to expand...

I know that Ion drives are fine in the void for accelerating continously, but they're far from ideal, the thrust you get from them is pathetic. The efficiency is what's appealing about them.

HStallion said:
In space there is nothing to slow you down so even a small amount of thrust can build and build over distances to travel at great speeds. Of course this needs to take into account slowing down as the ship gets near to its destination but still this is already a pretty big step up.
Click to expand...

I'm well aware of that. I know that ion drives have been used in the past. That's not my point.
 
H

HStallion

Now what's the next step in your master plan?
Steel said:
I know that Ion drives are fine in the void for accelerating continously, but they're far from ideal, the thrust you get from them is pathetic.



I'm well aware of that. I know that ion drives have been used in the past. That's not my point.
Click to expand...

My point is that you don't need a massive amount of thrust at the start of a space voyage, you build it up as you go. That and I'm sure they're continually trying to scale up the strength of ion thrusters.

danthefan said:
Does that work on Mars? I know the atmosphere there is really thin compared to Earth.
Click to expand...

The gravity of the planet is what they're most likely talking about, the atmosphere isn't that important.
 
D

danthefan

Member
HStallion said:
The gravity of the planet is what they're most likely talking about, the atmosphere isn't that important.
Click to expand...

An atmosphere will slow you down significantly to allow you land on the surface of a body. If you look at a recent example, Juno, it had to make a large retrograde burn or else it would never have gotten into Jupiter's orbit never mind land (and yes of course it wasn't going to land on Jupiter). The question was whether an ion drive would be suitable for a burn like that, I have no idea but I'm guessing not.
 
blu

blu

Wants the largest console games publisher to avoid Nintendo's platforms.
Fenderputty said:
Mar's atmosphere is basically nothing though? Not every expedition will be to land on a planetary body.
Click to expand...
Mars' atmosphere is surely not Venus', but it's way denser than the void. And it's not about landing - here's the theory behind aerobraking.

ed: sorry, linked wrong article
 
F

Fenderputty

Banned
blu said:
Mars' atmosphere is surely not Venus', but it's way denser than the void. And it's not about landing - here's the theory behind aerogravity assist.
Click to expand...

So what if our target is a smaller than Pluto sized object in the Kuiper Belt or an asteroid? Small moon around a large planet like Io?

I'm just spit balling. It seems like using Ion thrusters as long as possible would be ideal.
 
P

Par Score

Member
Fenderputty said:
So what if our target is a smaller than Pluto sized object in the Kuiper Belt or an asteroid? Small moon around a large planet like Io?

I'm just spit balling. It seems like using Ion thrusters as long as possible would be ideal.
Click to expand...

We're you not paying attention to New Horizons?

With our current technology, you just blow right by your target going incredibly quickly.

The potential for Ion thrusters is to blow right by your target going even faster.

Entering orbit of an object like Pluto is just not feasible... yet.
 
blu

blu

Wants the largest console games publisher to avoid Nintendo's platforms.
Fenderputty said:
So what if our target is a smaller than Pluto sized object in the Kuiper Belt or an asteroid? Small moon around a large planet like Io?
Click to expand...
Well, you aim at a nearby large planetary body, taking into account an approach traj to the moon.

I'm just spit balling. It seems like using Ion thrusters as long as possible would be ideal.
Click to expand...
Ion thrusters, to the best of my knowledge, is pretty much the best we have for long-distance space faring.
 
X

Xe4

Banned
That's really vool. Ion thrusters and laser solar sails are how we are going to send ultra light spacecraft to far away destinations in the not to distant future.

Par Score said:
We're you not paying attention to New Horizons?

With our current technology, you just blow right by your target going incredibly quickly.

The potential for Ion thrusters is to blow right by your target going even faster.

Entering orbit of an object like Pluto is just not feasible... yet.
Click to expand...
It's feasible but the timescale becomes far longer than the already rediculius time it takes. That means more chances for things to go wrong, which is a bad thing. Also the team when a spaceship enters orbit around Pluto would be entirely different than the one that started it.

It's not entirely clear the effort is worth trying to orbit Pluto, especially considering all the other cool objects in the Kuiper belt.
 
F

Fenderputty

Banned
Par Score said:
We're you not paying attention to New Horizons?

With our current technology, you just blow right by your target going incredibly quickly.

The potential for Ion thrusters is to blow right by your target going even faster.

Entering orbit of an object like Pluto is just not feasible... yet.
Click to expand...

Yes of course I paid attention to new horizons. We're not really doing efficient Ion engines in practice yet, though ... so like ... what's your point? I'm talking about possible future applications. In a world where all of our solar system is reachable due to the speed of Ion engines, we're going to find more we want to land on or orbit. Slowing down when half way there sort of defeats the point. Which is why I brought up standard thruster tech to slow.

Melon Husk said:
Why would you want to land an ion-thrusted ship anyway?
.
Click to expand...

Mars? Asteroid?
 
F

Fenderputty

Banned
Tossing out another hypothetical:

We increase efficiency enough that we can reach 50% of the speed of light in one year of acceleration and are off to Alpha Centauri. Would you want to just fly by the first ever extra solar system we've gone? I would hope we want to stick around and have data sent back to us. (sucks it would take around 5 years). So in that instance we would have to start slowing down about 1 year away give or take. Wouldn't it be more efficient to use standard thrust to slow down in less time? Are the forces too severe at those speeds?
 
H

HStallion

Now what's the next step in your master plan?
blu said:
Well, you aim at a nearby large planetary body, taking into account an approach traj to the moon.


Ion thrusters, to the best of my knowledge, is pretty much the best we have for long-distance space faring.
Click to expand...

Well maybe China will finally figure out if the EM Drive is actually the real deal or not.
 
WaterAstro

WaterAstro

Member
You only need a little bit of thrust to get around the solar system with reasonable time.

The problem isn't how to travel there, but protection from the dangers of space, mainly solar flare radiation.
 
Melon Husk

Melon Husk

Member
4000 tons of solar panels for a 7.5 MW system which would still take, what, 40+ days with a burn-and-flip? That's not accounting the rest of the ship, nor the ever weaking solar irradiance over time.

Fenderputty said:
Mars? Asteroid?
Click to expand...
I have simulated the outcome of this event:
Lg87q49.png

The water bottle's worth of thrust ain't gonna do it.
Fenderputty said:
Tossing out another hypothetical:

We increase efficiency enough that we can reach 50% of the speed of light in one year of acceleration and are off to Alpha Centauri. Would you want to just fly by the first ever extra solar system we've gone? I would hope we want to stick around and have data sent back to us. (sucks it would take around 5 years). So in that instance we would have to start slowing down about 1 year away give or take. Wouldn't it be more efficient to use standard thrust to slow down in less time? Are the forces too severe at those speeds?
Click to expand...

I'm not sure I comprehend your latest post, but with constant 1G+ of acceleration we're talking antimatter, not ion thrusters.
edit: No, it wouldn't kill us to accelerate to 0.5c in a year, I think it would be less than 1G.
 
Lister

Lister

Banned
Fenderputty said:
Tossing out another hypothetical:

We increase efficiency enough that we can reach 50% of the speed of light in one year of acceleration and are off to Alpha Centauri. Would you want to just fly by the first ever extra solar system we've gone? I would hope we want to stick around and have data sent back to us. (sucks it would take around 5 years). So in that instance we would have to start slowing down about 1 year away give or take. Wouldn't it be more efficient to use standard thrust to slow down in less time? Are the forces too severe at those speeds?
Click to expand...

In order to reach 50% of the speed of light in 1 year you'd need to constantly accelerate at around 1/2 a g (about 5 m/s2) unless my math is wrong :), I don't think we're there yet, but it's probably achievable.

The problem with using chemical rockets to slow down is that you have to bring them with you. So now you need a system that can accelerate the mass of your payload + the rockets to slow down + the fuel to slow down, and if you're trying to slow down from 50% of c, well, that means a LOT of fuel anda LOT of rockets (In fact I don't think we could generate that kind of thrust via chemical rockets, like ever).
 
I

iamblades

Member
Melon Husk said:
Why would you want to land an ion-thrusted ship anyway?



They had a nuclear reactor in The Martian.
Click to expand...

An RTG is not a nuclear reactor, and doesn't produce nearly enough wattage to power an ion drive for even a small space craft, much less a ship carrying humans to Mars rapidly. The 100 kW drive tested would accelerate a 100 ton mass at a laughably slow rate(roughly 6x10^-5 meters per second squared), and a 100 KW nuclear reactor is over 2 orders of magnitude more powerful than the largest RTG we have ever put into space.

A nuclear reactor that is powerful enough to do so would provide a fairly immense engineering challenge in space in terms of cooling and radiation management.

There is a very big reason why you don't want to go to mars as fast as you can though, you lose the free return. Even if we had a drive that could get us there faster, it makes more sense to use it to bring more payload instead.
 
N

nitewulf

Member
Am I wrong or is the author doing physics wrong? Why would there be a maximum velocity limit on chemical rockets of 5m/s? As long as you have fuel and can accelerate, your velocity would keep increasing (barring actual light speed limitation), no? The whole problem is chemical rockets burn through a lot of fuel too quickly, there's not that much you can carry and store.
 
M

moist

Member
Fenderputty said:
Tossing out another hypothetical:

We increase efficiency enough that we can reach 50% of the speed of light in one year of acceleration and are off to Alpha Centauri. Would you want to just fly by the first ever extra solar system we've gone? I would hope we want to stick around and have data sent back to us. (sucks it would take around 5 years). So in that instance we would have to start slowing down about 1 year away give or take. Wouldn't it be more efficient to use standard thrust to slow down in less time? Are the forces too severe at those speeds?
Click to expand...


Ideally you would accelerate at 1g until the half way point then decelerate at 1g until you got to Alpha Centauri so you effectively would have gravity on the ship for the majority of the trip.
 
X

Xe4

Banned
I should note, ion drives still rely on fuel (usually Xenon) to accelerate. They're advantageous (in space) over conventional rocketry, because their thrust to weight ratio is significantly higher. As it relies on fuel to accelerate, ion drives aren't really being considered as a way to accelerate to nearly c, at least in the near future.

A significantly more probably way to accelerate spacecraft to the speeds required for interstellar travel is using ultra light spacecraft powered by lasers on earth or the moon. This has the advantage of not having any fuel on board and is thus much more feasible. This has numerous problems too, however.

Ion drives are a wonderful way to send smaller spacecraft around the solar system, which is why they're being so heavily investigated.
 
I

iamblades

Member
nitewulf said:
Am I wrong or is the author doing physics wrong? Why would there be a maximum velocity limit on chemical rockets of 5m/s? As long as you have fuel and can accelerate, your velocity would keep increasing (barring actual light speed limitation), no? The whole problem is chemical rockets burn through a lot of fuel too quickly, there's not that much you can carry and store.
Click to expand...

The author wrote it poorly, she used the blanket term velocity when she means ∆v, which is limited on chemical rockets because the propellant makes up such a large amount of the mass. 5 km/s is not exactly a hard limit though, you can exceed it if you are only accelerating a small payload, but it is decent rule of thumb for practicability, because the mass ratios for chemical rockets follow an exponential curve as the delta-v increases.

The way the author wrote it is extra confusing because it's using ∆v from LEO, when LEO is already substantially faster than 5 km/s.
 
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