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NASA's Ion Thruster Sets Continuous Operation Record
cylonlover writes "NASA's Evolutionary Xenon Thruster (NEXT) ion engine has set a new world record by clocking 43,000 hours of continuous operation at NASA's Glenn Research Center's Electric Propulsion Laboratory. The seven-kilowatt thruster is intended to propel future NASA deep space probes on missions where chemical rockets aren't a practical option. The NEXT is one of NASA's latest generation of engines. With a power output of seven kilowatts, it's over twice as powerful as the ones used aboard the unmanned Dawn space probe, yet it is simpler in design, lighter and more efficient, and is also designed for very high endurance. Its current record of 43,000 hours is the equivalent of nearly five years of continuous operation while consuming only 770 kg (1697.5 lbs) of xenon propellant. The NEXT engine (PDF) would provide 30 million newton-seconds of total impulse to a spacecraft. What this means in simple terms is that the NEXT engine can make a spacecraft go (eventually) very far and very fast."
This ion thruster placed on Voyager 1 would have taken it up to 37 km/s over 5 years compared to the 17km/s it is going now. Not part of my calculations is that Voyager 1 would have been slightly lighter due to the reduced fuel load. i don't have exact enough numbers to do the calc, but it would have likely been in the low 40's km/s.
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The simple concept that we now have "Ion Thrusters" is extremely cool to me. Only "Warp Drive" would be cooler, be we have a ways to go there.
Most likely this thing was not aboard any ship or probe or any other object in outer space. This thing is being developed, so it is likely attached to some instruments in a lab where they can monitor it continually and make sure there aren't any problems. Likely they shut it down periodically to look for any problems, signs of breakdown or other signs that this cannot be scaled up for any reason.
So how far and how fast are irrelevant. There are enough numbers in the summary that you can do your own calculation on any object you like.
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while consuming only 770 kg (1697.5 lbs) of xenon propellant.
Last I heard, xenon was a gas, and that sure sounds like an awful lot of it - how much is left (on our planet)?
Although acceleration is not the same as speed, AC is right. Even if you assume the probe's weight is negligible, you begin to run into issues with thrust to weight of fuel. Over the five years cited in this story, the ion thruster consisting of fuel only would get you to 75km/s, or about a 14,000 year flight to alpha centauri. Scaling up doesn't help much as the ion thruster has to accelerate a larger mass.
See my journal for slashdot ID's by year. Mine created in 2005. http://slashdot.org/journal/289875/slashdot-ids-by-year
The nice thing is if you want a more recent update, just start calling all of the people on Slide 6. Then again, this is a four year old presentation...some have probably moved onto other positions.
Flamebait
Serious inquiries only.
My calculations would say it probably went at a speed of around 0km/second, placing it now around 0km from Earth after 5 years.
EMail: 0110001101100010010000000110001101110010 0110000101111010011011100110000101110010 0010111001100011011011110110
Check your maths. My calculations place it about .001 km from Earth...
How come Slashdot never gets Slashdotted?
I keep hoping, but interstellar is extremely difficult. It won't happen in our lifetimes. To get to Alpha Centauri in just 70 years requires acceleration to near 0.1c. That takes way more energy than we can currently give our probes. Thinking that a gravity assist can help significantly with that is like thinking you can make your car go significantly faster by having a person stand beside the road and blow air at your back as you pass.
Maybe we could eventually swing something on the order of 700 years. But just 70 years is really pushing the longevity of our current designs. Plutonium doesn't last long enough. In any case, how to make a probe last 700 years is only half the problem. Keeping a project alive, relevant data fresh on current media, and people trained for such a length of time would be the other half. 700 years is an awful long time for circumstance to scuttle the project. Can NASA or any other agency last that long? Can the US?
Barring catastrophe, we will eventually do it.
Intellectual Property is a monopolistic, selfish, and defective concept. It is "tyranny over the mind of man"
Likely they shut it down periodically to look for any problems, signs of breakdown or other signs that this cannot be scaled up for any reason.
.
Not. It was 43,000 hours of continuous operation.
Doesn't sound like alot, but 75km/s would still make it the fastest man-made object in history.
This is a question I've wondered for years and have never seen answered: why can't chemical thrusters used on satellites (particularly in geostationary orbit) be replaced with ion ones? It seems to me that running out of fuel is the primary method of "death" for a geostationary satellite. Do station-keeping maneuvers really require that much thrust?
I thought to use something as fuel in an ion thruster, it has to be able to ionize? Xenon is about as inert as it gets and really isn't useful for anything because nothing reacts with it in any way. In fact, wasn't hydrogen or something the typical fuel for an ion thruster? Can one of the hundred or so ion thruster engineers that are likely here on slashdot (lol) explain it to us?
For a more earthly comparison, it would take about 8.6 seconds to drive across Kansas at that speed.
http://en.wikipedia.org/wiki/Kansas
There are two types of people in the world: Those who crave closure
> Thinking that a gravity assist can help significantly ...
http://en.wikipedia.org/wiki/Gravity_assist
Right. Most folks, even amateur space enthusiasts like us, don't really understand the gravity "slingshot" and how it works. Some have the idea that you can just accelerate like a demon toward a given planet or moon, whip around it and somehow gain all sorts of new velocity. That's not so.
What you will gain is part of the orbital velocity of the object that you're "slingshotting" around. Nice boost and it makes a difference -- our space probes use it all the time -- but it's not some magical means by which you can accelerate to C-fractional speeds.
Cogito, igitur comedam pizza.
That's still a lot of time to spend in Kansas.
But it's still a lot better than the 8.6 hours it takes to drive across it.
There are two types of people in the world: Those who crave closure
Strictly speaking, that's not correct, because a significant amount of xenon is generated during uranium fission reactions and some of that will decay to stable Xe isotopes. I don't know if that is possible to recover in commercial quantities at a reasonable price, but there are ways to do it.
To get to Alpha Centauri in just 70 years requires acceleration to near 0.1c.
And then to actually stop there to land on a planet requires deceleration by nearly 0.1c.
#naabhaprzrag, #sverubfr-000, #agi-fcbafberq, negvpyr[pynff*=' negvpyr-ary-'] { qvfcynl: abar !vzcbegnag; }
If they shut them down how could it be claimed to be continuous operation? You do know that continuous means "uninterrupted", right?
Depends, if the Xenon is shot back at Earth it could re-enter the atmosphere and be ready to be extracted again.
I read the internet for the articles.
Maybe they mean "continuous" operation the way ISP's mean "unlimited" bandwidth?
The villainous Tie fighter pilot straps in, ready to squash the rebellion once and for all. He charges his heavy blasters, straps into the seat, and twists the knob for full throttle, feeling the exhilarating rush of a barely perceptible acceleration and the knowledge that in two or three years time he will be moving at a pretty good clip, just so long as he never has to change directions.
I read the internet for the articles.
A few years of economic difficulties and some populist loudmouths talking about draconian cuts, and boom! There she goes.
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
Bullshit!
I send photons out my flashlight way faster than that.
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
Repeat:
"To utter in dulication of another's utterance".
Which my post wasn't. Fail.
Nah, we'll need to give them a bit more thrust before they become useful. Considering the fighter itself has no life support, the pilot will be dead before he gets to above walking pace if we use the current model.
My maths are 0.00074295 km from the Earth. :)
Serious? Seriousness is well above my pay grade.
Tse.Tse. It's underground, you both got the sign wrong.
Trying to work a project for 700 years would also inevitably land you in the position of launching something that is 300 years newer that would pass your 300 year old probe long before it got to it's destination, because propulsion tech is 300 years better.
I mean, 700 years ago was 150 years before Copernicus created his heliocentric model of the solar system, and was lambasted for it. Now we've got probes on their way out of the solar system that he was mostly correct about.
Slashdot still doesnâ(TM)t support Unicode after it was added to the HTML standard in 1997.
Hoo, clever! What, no Wizard of Oz reference? Those are always so insightful.
The christian church (in various forms) has been around for millenia awaiting the return of their messiah. That is quite a bit of longevity. Perhaps we should convert NASA to a religion, then there will be no problem having someone wait a few hundred years for the return of their white metallic savior.
I just like saying it, it sounds so cool. Ion Thrusters....
If you could reason with religious people, there would be no religious people
Yes. But it was on a test stand, so that *IF* problems developed, they could shut it down to fix the problem. Think of it as a debugging run.
I think we've pushed this "anyone can grow up to be president" thing too far.
>> Barring catastrophe, we will eventually do it.
And where did you pick that up ? On the last 50 tv shows/sci-fi movies that you looked .. ?
You could just as easily say we're all dead. Both statements are dellusional, unfortunately influenced by above mentioned that influenced you to think this way.
Offtopic, but relevant in some sort of abstract way: Then people wonder why media can influence people opinion (to give a green light) when it comes to bombing 20 countries in 10 years.
And my personal opinion.. I consider you arrogant people guilty of war crimes, suffering, poverty, and everything else negative on this country. Fuck Bush and Obama what you are.
Through hardship to the stars! (Kansas state motto)
I really doubt that "we", i.e., the stay-at-homes, will ever do it. The only way to have a project last for 700 years is to inspire true commitment. A colony ship might work, but but the time they got there, they wouldn't be interested in living on a planet, and this would need to be planned for. (And by planned for, I don't mean rig things to coerce them.)
The other possibility that I see is that an AI could be designed that WOULD maintain focus for that long and longer.
OTOH, if we don't choose to remain confined to Earth, the people will eventually be spending their lives in self-contained colony worlds. Given sufficient energy sources (independent of the sun) eventually some of them will choose to leave the area. Either political or religious disagreements would work as a reason. Speed of travel will be less important than safety, but speed of becoming "lost" might be vitally important, depending on the reason for leaving. I'm not sure they would be particularly interested in other suns, but they'd be interested in the matter that circles them...still, brown dwarfs might be just as good, or wandering planetoids. (Planets will be less desireable, because they are more difficult to extract resources from.) Note that while wandering, a high speed will be very undesireable. You want to be moving fast enough to reach new resources but not so fast that you pass them faster than you can take what you want from them. Still, suns will be areas dense in usable resources.
This concept has been called "MacroLife". When the wandering colony encounters a rich resource, it builds a new colony or so and splits, reproducing. It probably requires controlled fusion to make it work, but it might work in a limited way with only fission power.
I think we've pushed this "anyone can grow up to be president" thing too far.
That would be pretty pointless though - pushing directly away from the planet you're orbiting just changes your orbital eccentricity, without significantly changing your orbital energy. Meaning that when you reach the opposite side of your orbit you'll be even closer to the planet than you were before. And since you'd have to be pretty close to begin with for a significant portion of your exhaust to collide with the planet that probably means you've just executed a de-orbiting maneuver. And actually, since we're talking about a very low-thrust, very long-duration engine, what we're probably doing is just continuously cancelling out the orbital adjustment we made while on the opposite side of the planet.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Sure, it's not the cheapest reaction mass, but at 220 Watt-hour/liter it's not exactly terribly expensive to extract from the atmosphere, and it is well suited to ion-drive use.
What I wonder is is it actually a particularly valuable substance (usefulness as opposed to price) for anything else, or can we go ahead and use up the planet's supply* as spacecraft "fuel" in good conscience. From what I can tell it's used primarily for lighting, radiation detectors, and as a general anesthetic (How does that work? I'd expect a noble gas to be biologically inert.) All applications for which plenty of other options are available. Unlike helium which has many unique properties that make it extremely valuable and a real shame to waste in party balloons just because it's inexpensive (since helium readily escapes into space every gram we vent into the atmosphere is gone forever)
*admittedly a long-term consideration, and likely we'll have found other sources long before it's an issue
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Ahhh, I remember when AT&T Worldnet screwed that up for everyone. They gave "unlimited" and would periodically bump their users offline. Those of us who had our machines automatically reconnect and notify us of our new IP were apparently a pain. "Unlimited" became "Unlimited, yet limited to x hours per month" and if you did stay connected all month, it was something like a $5,000 charge for the extra time, even if you barely transferred anything.
I almost preferred the per minute billing. I couldn't get back to my home machine that way though.
Serious? Seriousness is well above my pay grade.
Hardly, if both sides had such low-power ion-drives the defenders couldn't even get off the surface and would be sitting ducks. As long the rebels could avoid the moon's point-defense systems they could just eject annoying droids at sensitive targets until the whole place came crumbling down.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Actually you're probably better stripping off the electrons than trying to add them. A naive ion thruster consists of two high-voltage electrodes - the positive electrode strips off some electrons from colliding neutral atoms, which then get powerfully attracted to the negative electrode while applying an equal-but-opposite force to the thruster itself (See "lifters", a fun hovering ion-drive you can build in your garage, assuming you're competent to play with tens of thousands of volts)
The critical evaluation of the "effectiveness" of the reaction mass is the charge per mass - i.e. neutrons are "wasted" mass in the ions since they don't contribute to the accelerating force. Likewise any inner-shell (firmly attached) electrons that you fail to strip from the ions effectively neutralize the same number of protons. By that measure hydrogen is as good as it gets - it has no neutrons and its single electron is easy to strip away giving you the maximum possible charge per unit mass. The only problem with hydrogen is that it's devilishly difficult to store - as a gas it's extremely low-density, liquifying it requires high pressures or extremely low temperatures, and it's small size allows it to seep right through even even thick steel walls. It's the added mass of the container that makes it unattractive as a reaction mass. Well, that and its reactivity - something like xenon that's relatively dense and inert is much easier and safer to work with.
Your F=ma argument amounts to "which is heavier, a pound of bricks or a pound of feathers". Neither, obviously. The real question is which is it easier to carry several hundred pounds of.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Isn't this where your Bussard collectors come in. Now, I understand that there's not likely to be a lot of Xenon in interstellar space, but it's possible that once NEXT is producing plenty of data, we can figure out how to get something working with hydrogen.
Assuming a 0 or microgravity environment, how far is "very far"?
The fact that it has a high specific impulse is good, if one were traveling though very empty space. But, the gravitational slingshots and interplanetary highways require short bursts of high energy, at very specific times, rather than high efficiency.
Still, though, the problem which neither of these addresses, and that none of the solutions I have seen so far address, is the collision with other masses.
This is somewhat disingenuous. Physics is physics and rocket technology hasn't improved much since the Centaur (hydrogen rocket) engine in the mid-1960s because they're already getting close to the theoretical maximum energy from chemical rockets. This is sort of like saying we shouldn't develop spoons and forks at the turn of the last millennium because by 1935 we'll have developed the spork. Cutlery has been a mature technology for about two thousand years now, and you can't really improve on it. Short of FTL travel we're looking at scramjets and multigenerational probes.
moox. for a new generation.
This is somewhat disingenuous. Physics is physics and rocket technology hasn't improved much since the Centaur (hydrogen rocket) engine in the mid-1960s because they're already getting close to the theoretical maximum energy from chemical rockets. This is sort of like saying we shouldn't develop spoons and forks at the turn of the last millennium because by 1935 we'll have developed the spork. Cutlery has been a mature technology for about two thousand years now, and you can't really improve on it. Short of FTL travel we're looking at scramjets and multigenerational probes.
Cutlery has changed significantly, even in the 700 year period we were discussing:
Slate article
I'm not sure how it affects your argument, but perhaps you should try to find an example of something that hasn't changed significantly in the past 700 years.
Isn't 0.1c a velocity?
The FOCAL mission might benefit from this kind of tech, seeing as it involves getting a telescope 550AUs out from the Sun and using the sun as a lens.
I do not want your cheap brainburning drugs. They are useless for work. And I am a working man today.
Because new ideas never happen, right?
There probably was once someone who said that the telephone could never be improved, because a human can only talk so fast. Then digital communications happened.
Just because you and I can't think of it, doesn't mean it won't happen.
Slashdot still doesnâ(TM)t support Unicode after it was added to the HTML standard in 1997.