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NASA's NEXT Ion Thruster Runs Five and a Half Years Nonstop To Set New Record

timothy posted about 10 months ago | from the slow-and-steady-and-breathe-and-good dept.

NASA 184

cylonlover writes "Last December, NASA's Evolutionary Xenon Thruster (NEXT) passed 43,000 hours of operation. But the advanced ion propulsion engine wasn't finished. On Monday, NASA announced that it has now operated for 48,000 hours, or five and a half years, setting a record for the longest test duration of any type of space propulsion system that will be hard to beat."

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184 comments

Perfect analogy for NASA (5, Funny)

Gothmolly (148874) | about 10 months ago | (#44121125)

Running your engines at full power but standing in one spot for 5 years. That pretty much sums up our space program since Apollo.

Re:Perfect analogy for NASA (5, Insightful)

h4rr4r (612664) | about 10 months ago | (#44121251)

So then those rovers on Mars are figments of my imagination?

Our space program since Apollo has gotten better. Unless you think their is some scientific value in sending humans to play golf on other worlds.

Re:Perfect analogy for NASA (5, Insightful)

Penguinisto (415985) | about 10 months ago | (#44121541)

Our space program since Apollo has gotten better. Unless you think their is some scientific value in sending humans to play golf on other worlds.

Laugh and minimize all you want, but the one geologist to land on the Moon [wikipedia.org] managed to learn more (and faster) in his one short trip than all of the Mars rovers combined. Why, you ask? Because he didn't have to waste time looking at a picture and speculating on what a shadow or shape looked like it could be. Instead, he just walked up to an item of interest, looked at it, and was able to discern in seconds something that, well, takes teams of scientists weeks on end to speculate over nowadays.

...then there's that niggling fact that someday, space may be the only habitable home we have left after this one gets wrecked - be it by us or by the first asteroid that decides not to simply pass by. It would be nice to already have the tech to live there - preferably long before we're forced to learn it on a tight schedule.

Re:Perfect analogy for NASA (2)

h4rr4r (612664) | about 10 months ago | (#44121571)

I am not laughing nor minimizing. Scientists are not stuck with pictures, but tools not even available during the Apollo era are on those rovers to sample rocks.

I agree, but we simply will not bother until we are forced. We can't even get people to update coal power plants, you can forget them wanting to spend a dime on this.

Re:Perfect analogy for NASA (4, Interesting)

Dyolf Knip (165446) | about 10 months ago | (#44121975)

Not really. The tools are impressive, but mostly in how they try to overcome the crippling need to run remotely from umpteen million miles away.

Let's have a look: http://en.wikipedia.org/wiki/Curiosity_(rover)#Instruments [wikipedia.org]

Lists 14 instruments. But 5 of them are just cameras, strategically placed because they can't be moved. My friend the amateur photographer could do much better with her DSLR. The "environmental monitoring station" measures humidity, pressure, temperatures, wind speeds, and ultraviolet radiation; not exactly groundbreaking stuff here. Same with radiation assessment. There's a robotic arm capable of drilling holes a whopping 2" deep and a dust removal tool, commonly known as a 'broom'. The "Dynamic Albedo of Neutrons" sounds sexy as hell, but then you realize a person with a trowel could do the same job.

The other instruments are all spectrometers and a chromatograph. The means by which they work are novel, due to the aforementioned remote requirements, but the end result is not really different from what could be done in any decent lab 50 years ago. Honestly, a decent scientist with a shovel and a few thousand dollars in high school lab gear could do better than all the rovers ever sent. God help us if we ever needed a probe to do something _really_ difficult.

So by all means, send what probes are needed to figure out how to get people there, but anything beyond that will just provide minimal information at enormous cost.

Re:Perfect analogy for NASA (2, Insightful)

Anonymous Coward | about 10 months ago | (#44122521)

My friend the amateur photographer could do much better with her DSLR.

Can your friend do better while fitting in a small box without life support? If we took the budget, both in terms of costs, volume, and amount of equipment needed to send a person there, that could buy a lot of cameras, and ones that could move around just as much as your friend could move them around.

The "Dynamic Albedo of Neutrons" sounds sexy as hell, but then you realize a person with a trowel could do the same job.

Not quite the same as a person with a trowel, considering neutron sources get used for analysis by geologists on Earth even where there are plenty of trowels. Even if you had a person on Mars, with a trowel or not, it would be quicker for them to drag a sled behind them with a similar instrument than to dig up the ground everywhere.

The other instruments are all spectrometers and a chromatograph. The means by which they work are novel, due to the aforementioned remote requirements, but the end result is not really different from what could be done in any decent lab 50 years ago. Honestly, a decent scientist with a shovel and a few thousand dollars in high school lab gear could do better than all the rovers ever sent.

50 years ago, such equipment was quite bulky and not very rugged. While you could do such work with a 50 year old lab, you wouldn't want to send a such a whole lab to Mars. Especially in the last decade or two, such equipment has become much more portable allowing for their use in the field, on Earth or not. There is plenty of equipment that went from, "I'll have to take these samples back to look at them," to "we could set up a large tent or shed to do local work," to, "I have one in the back of my truck."

So by all means, send what probes are needed to figure out how to get people there, but anything beyond that will just provide minimal information at enormous cost.

Because sending a person will provide slightly more than minimal information at an even more enormous cost? If you had the budget you would spend on such a mission spent on probes, you would quickly make up for a large part of the lack in versatility, and for most work surpass what the person can do in terms of speed by having many probes work in parallel.

Re:Perfect analogy for NASA (2)

Rhipf (525263) | about 10 months ago | (#44121743)

Actually the geologist learned more than the Mars rovers combined since the rovers didn't land on the moon. Its hard to learn more about the moon than a live person when you are millions of miles away.

Re:Perfect analogy for NASA (1)

kamapuaa (555446) | about 10 months ago | (#44121995)

The guy who went to the moon and didn't find any evidence of water? And now is dedicating himself to disproving the idea of global warming? I'd rather have robots.

Not totally fair to say he couldn't find water, but Opportunity found it, while the geologist couldn't.

Re:Perfect analogy for NASA (1)

Sperbels (1008585) | about 10 months ago | (#44122121)

Far easier to find evidence of water on a surface that actually had flowing water on it at one point. Mars did, but the moon didn't. Your argument is idiotic, and hopefully you can see the ridiculous logic (or lack thereof) you just attempted to apply.

Re:Perfect analogy for NASA (1)

kamapuaa (555446) | about 10 months ago | (#44122181)

If the geologist was far better than a robot, how come the geologist didn't learn the most basic geological facts?

Re:Perfect analogy for NASA (1)

Sperbels (1008585) | about 10 months ago | (#44122533)

If the geologist was far better than a robot, how come the geologist didn't learn the most basic geological facts?

He did. He learned there was no evidence for flowing water on that part of the moon...because there was never flowing water on the moon. Seriously? Are you trolling or do really not understand this?

Re:Perfect analogy for NASA (5, Interesting)

Anonymous Coward | about 10 months ago | (#44122067)

...then there's that niggling fact that someday, space may be the only habitable home we have left after this one gets wrecked

Don't take offense, because I'm sure you're thinking this because you've been told so many times that this would be the case, but why is there the common belief that mankind would find a complete vacuum, devoid of ANY resources other than photons, be more suitable for our life than the Earth would be in any state of pollutive decay?

If we can build capsules for space, why not do the same thing here and protect ourselves from the elements? We can use space suits to travel around the exterior here, too, extracting useful resources from the fetid scum we created, and if we can shield ourselves from cosmic radiation, why wouldn't we be able to shield ourselves from any possible post-nuclear-holocaust radiation?

I'm certainly not suggesting that NASA is a waste of money - I am an aerospace engineer, after all - I'm just saying that if your house became infested with termites, you wouldn't resign yourself to abandoning it and living on a houseboat in the middle of the ocean because there are no termites in the middle of the ocean.

Re:Perfect analogy for NASA (0)

Anonymous Coward | about 10 months ago | (#44122777)

Space is most definitely a hostile environment. On the other hand, it's infinitely more survivable than, say, Venus.

Space is largely *passively* hostile. Outside of debris moving at cosmic speeds, space presents some fairly basic engineering issues, after which survival is sorted out until someone makes too big of a mistake.
Venus, on the other hand, is *actively* hostile. It doesn't just want to kill you if you make a mistake, it wants to eat your shelter, and destroy you even when you're doing everything right.

Venus is very similar to Earth in many ways. Absent the runaway greenhouse effect, she is a potentially habitable planet. If we manage to do that to Earth, Space looks utterly hospitable in comparison.

Re:Perfect analogy for NASA (2)

Intrepid imaginaut (1970940) | about 10 months ago | (#44122877)

devoid of ANY resources other than photons, be more suitable for our life than the Earth would be in any state of pollutive decay?

Those photons are quite a resource in their own right. But there is also every element you can find on earth floating around in ridiculous abundance, and easier to access too.

As to why, well there aren't many reasons to choose a station over earth, but there are plenty of reasons to choose a station over anywhere else. We would have perfect control over the gravity in a station for a start, which neatly sidesteps a whole host of problems with either bone decalcification or excessive gravity, not to mention being able to fine tune the environment any way we like. The idea might seem a little claustrophobic at first glance but really, it would be like living in a large city with vacations elsewhere from time to time.

I predict we'll colonise space itself long before we start colonising other worlds.

Re:Perfect analogy for NASA (0)

Anonymous Coward | about 10 months ago | (#44123069)

No, but the other issue is that for us to land hmans on Mars, we need crafts that can land there, and robots to help. With Apollo, it was just a day trip. With Mars, it will not be 2 years, but far more likely a decade stay. And before you claim that these things are easy to develop, you will note that we are the only nation with truly successful landings on Mars. USSR sent a number of them, but only 1 actually landed, and it lasted for less than 20 seconds. ESA has lost one as well. Heck, Russia and China simply tried to go to Mars and failed. There is NOTHING easy about all of this.

However, we have private space up and coming now. With Red Dragon, we will gain not just the ability to double the amount of science that has actually landed on Mars, but it will provide the craft for landing humans on mars as well. And yes, red Dragon has gained a great deal from NASA's experience with robotics and engines.
 
I would have to say that if O can kill the SLS, push private space, and can stop the neo-cons from the opposite actions, then we will be on the moon by 2020, and Mars by 2025. If the neo-cons are successful, then we will be one of the last on the moon and mars.

Re:Perfect analogy for NASA (0)

Anonymous Coward | about 10 months ago | (#44122153)

So then those rovers on Mars are figments of my imagination?

Our space program since Apollo has gotten better. Unless you think their is some scientific value in sending humans to play golf on other worlds.

I don't see why space exploration have any value at all unless we intent to eventually move off world.
Yes, it is cheaper to send robots, but it is even cheaper to observe from Earth, or not at all.

Re:Perfect analogy for NASA (1)

h4rr4r (612664) | about 10 months ago | (#44122755)

Knowledge has no value to you?
That must be one hell of a miserable existence you live.

Re:Perfect analogy for NASA (5, Informative)

fuzzyfuzzyfungus (1223518) | about 10 months ago | (#44121259)

Would it be insufferably pedantic to mention Pioneer 10/11, Explorer 49, Mariner 10, Helios A/B(with Germany), Viking 1 and 2, Voyager 1 and 2, Pioneer Venus 1 and 2, ISEE-3(with EU), Magellan, Galileo, Hubble(with EU), Ulysses(with EU), Mars Observer, Clementine, WIND, NEAR Shoemaker, Mars Global Surveyor, Mars Pathfinder, ACE, Cassini-Huygens(with EU), Lunar Prospector, DS1, Stardust, Mars Odyssey, Genesis, Mars Exploration Rovers, MESSENGER, Deep Impact, Mars Reconnaissance Orbiter, New Horizons(in transit), STEREO, Pheonix, Dawn, Lunar Reconnaisance Orbiter, Solar Dynamics Observatory, Juno, GRAIL, Mars Science Laboratory, and Radiation Belt Storm Probes?

Sure, our man-in-a-can cred isn't what it used to be; but I, for one, welcome our robotic overlords.

Re:Perfect analogy for NASA (0)

Anonymous Coward | about 10 months ago | (#44121789)

You forgot New Horizons. It's almost to Pluto, we're busy rehearsing the flyby right now.

Re:Perfect analogy for NASA (0)

Anonymous Coward | about 10 months ago | (#44121331)

It also sums up the fact that space is an enormous deadly vacuum with no real reason to send people there.

Re:Perfect analogy for NASA (2, Insightful)

Penguinisto (415985) | about 10 months ago | (#44121569)

It also sums up the fact that space is an enormous deadly vacuum with no real reason to send people there.

Hate to say it, but we already live in space - this big ball of mud and air that we call home happens to float in it. It'd be nice to get out in the neighborhood a little, no?

Re:Perfect analogy for NASA (1, Flamebait)

cdrudge (68377) | about 10 months ago | (#44121371)

The problem is that the thruster only produces 236 mN of thrust. NASA's bureaucracy coupled with the infinitely massive boat anchor called the US government has created an object so huge that 236 mN over 5.5 years has only moved it an imperceptible distance.

Too bad it's at NASA (-1, Flamebait)

rhadamanthus (200665) | about 10 months ago | (#44121155)

Which all but guarantees that this engine will never do anything more.

Re:Too bad it's at NASA (3, Informative)

fuzzyfuzzyfungus (1223518) | about 10 months ago | (#44121185)

Which all but guarantees that this engine will never do anything more.

Sort of like the ion thruster on the Dawn [nasa.gov] probe, which left Vesta about a year ago with an ETA on Ceres sometime in 2015?

Re:Too bad it's at NASA (1)

nojayuk (567177) | about 10 months ago | (#44122885)

The ion thrusters on the Japanese Hayabusa asteroid sample-return mission kept on breaking down but after a lot of TLC the main spacecraft did get back to Earth and its sample capsule was recovered.

A European Space agency probe, the 370kg SMART 1 was powered by an ion motor and flew from Earth orbit to Lunar orbit under ion propulsion in 2004. It burned 80kg of fuel over about 13 months producing 68 mN of thrust.

Could we achieve 1G of thust. (4, Interesting)

jellomizer (103300) | about 10 months ago | (#44121217)

My Hope if we could build a space craft that can accelerate 9.8m/s^2 (1g) for the duration of going to Mars and Back. You go to at 1g half way to mars, then you decelerate at 1g the other half. Orbit for a period of time. Drop down a landing party for a while. And go back at 1g half way decelerate at 1g the other half. Then you would have a good long range mission with out the 0g effect messing up the body.

Re:Could we achieve 1G of thust. (1)

Prof.Phreak (584152) | about 10 months ago | (#44121285)

Not to mention that at 1g it wouldn't take long to get to speed of light :-)

Re:Could we achieve 1G of thust. (0)

tilante (2547392) | about 10 months ago | (#44121343)

No matter what your acceleration is, it will take you infinite time to get to the speed of light. Relativity, man.

Re:Could we achieve 1G of thust. (0)

Anonymous Coward | about 10 months ago | (#44121633)

Sure, but the distance you need to travel will become shorter.

Re:Could we achieve 1G of thust. (1)

Anonymous Coward | about 10 months ago | (#44122001)

That just, like, your opinion, man.

Re:Could we achieve 1G of thust. (3, Informative)

Overzeetop (214511) | about 10 months ago | (#44121655)

Without relativistic effects about a year but, as noted by the sibling poster, relativity gets in the way from the outside observers point of view. And what good is next day delivery if the goods are 1 day old and the recipient's great, great, great, great, great granddaughter has to sign for the package?

Though practically impossible with current or proposed technology, it would, indeed, take only 35 days to reach 0.1c, and we'd be 225 million km from our starting point, ignoring gravitational effects of other bodies. Though in astronomical terms that's not very far (less than the diameter of Earth's orbit) - less than half way to Jupiter on the closest possible approach.

Re:Could we achieve 1G of thust. (2)

MBGMorden (803437) | about 10 months ago | (#44121977)

Without relativistic effects about a year but, as noted by the sibling poster, relativity gets in the way from the outside observers point of view. And what good is next day delivery if the goods are 1 day old and the recipient's great, great, great, great, great granddaughter has to sign for the package?

As a method of delivery its worthless, but as a method of colonization its pretty neat. If by some stretch of the imagination we could identify a planet as definitely habitable from here we send off a crew at some significant fraction of the speed of light. I'm sure the people actually travelling there care a lot more about the passage of time than those of us back on Earth (they'd have to be specially selected with the idea that everyone back on Earth that they knew would be dead by the time they arrived - for settling one could take their family with them or just select people without any existing family).

Once they get there they could setup a base of operations/colony and begin communicating back with Earth (I assume that the project itself would still be up and running).

Ideally if we could work out communications via quantum entanglement they could have take a quantum entangled particle with them to make communications faster back to Earth. Perhaps even build some sort of router to hook the computer LAN on that side back to the internet on this side. Probably would be low-bandwidth but latency would be tolerable.

Re:Could we achieve 1G of thust. (1)

elfprince13 (1521333) | about 10 months ago | (#44122101)

Ideally if we could work out communications via quantum entanglement they could have take a quantum entangled particle with them to make communications faster back to Earth. Perhaps even build some sort of router to hook the computer LAN on that side back to the internet on this side. Probably would be low-bandwidth but latency would be tolerable.

Wrong. Classical (i.e. useful) communication via quantum entanglement cannot exceed the classical speed limit. See the no-cloning [wikipedia.org] and the no-broadcast [wikipedia.org] theorem (or just read the first paragraph on quantum teleportation [wikipedia.org]).

Re:Could we achieve 1G of thust. (1)

pr0fessor (1940368) | about 10 months ago | (#44122597)

The idea has been used so much in science fiction Ansible [wikipedia.org]. I think the idea of using quantum entanglement sounds like it came straight out of Ender's Game or possibly an episode of Eureka.

This isn't my field of study so no helpful tips on how to make it actually work, just thought I would point out why people think it might.

Re:Could we achieve 1G of thust. (1)

elfprince13 (1521333) | about 10 months ago | (#44123157)

Oh, I'm not at all in the dark as to why people think it could work or where they get the ideas (and I'm a huge Ender's Game fan myself), but it's still a disturbingly common misconception that needs to be corrected.

Re:Could we achieve 1G of thust. (0)

Anonymous Coward | about 10 months ago | (#44123121)

Just a minor speedbump. All we need to do is to change our idea of information, and voila - we can communicate via quantum entanglement. Easy-peasy. We had a few leaps like that in the past, why not now? We just need to wait for another brilliant mind to enlighten us...

Re:Could we achieve 1G of thust. (1)

sjames (1099) | about 10 months ago | (#44122299)

So it takes about a year to get up to (oh, lets say 0.75c) and the same to decelerate. That puts a robotic mission to the closest stars on the table.

Re: Could we achieve 1G of thust. (0)

iamhassi (659463) | about 10 months ago | (#44121293)

But wouldn't this engine continue to build speed forever since there is no resistance in space? So 1g should be easily achievable.

Re: Could we achieve 1G of thust. (-1)

Anonymous Coward | about 10 months ago | (#44121349)

Are you ... serious? Are you a troll? Have you finished high school physics yet?

Re: Could we achieve 1G of thust. (2)

jellomizer (103300) | about 10 months ago | (#44121373)

Still you need to fight momentum. If you have a ship big enough to hold heavy people with heavier supplies that is a lot of momentum to fight all the time. Sure we can burst speed of multiple G's but once the fuel runs out and the ship goes at a constant speed we are down to 0g.

Re: Could we achieve 1G of thust. (1)

GodfatherofSoul (174979) | about 10 months ago | (#44122757)

It won't be like driving a car. You accelerate 1/2 of the way there, turn around, and decelerate the rest of the way. That way you're at 1 G the whole time.

Re: Could we achieve 1G of thust. (0)

Anonymous Coward | about 10 months ago | (#44121385)

Acceleration is what determines gravity. 1G gravity would be achievable as long as you keep accelerating and its thrust is equivalent to 1G

Re: Could we achieve 1G of thust. (1)

Binestar (28861) | about 10 months ago | (#44121395)

Really? Or are you trolling? 1G is acceleration, not speed. So build at much speed as you want, it's still building it at whatever your acceleration is. You're not suddenly "traveling at 1G"

Re: Could we achieve 1G of thust. (0)

Anonymous Coward | about 10 months ago | (#44121495)

Heh, my non-physics brain went to the same thought initially, but we're thinking velocity (m/s) and not acceleration (m/s2 or g). 1g = 9.8m/s2

Re: Could we achieve 1G of thust. (0)

Squidlips (1206004) | about 10 months ago | (#44121671)

Nope! As you approached the speed of light, undesirable things start happening such as increasing mass etc. Basic relativity...

Re: Could we achieve 1G of thust. (1)

Evtim (1022085) | about 10 months ago | (#44121891)

There is no resistance but the mass of the ship and the cargo will increase with the speed. Thus, if you had to spend, say, Z amount of joules to achieve 1g acceleration at low (compared to c) speeds, you woudl need many more joules to sustain the 1g acceleration the closer you are to c.

Re: Could we achieve 1G of thust. (0)

Anonymous Coward | about 10 months ago | (#44122629)

You would need more and more power to maintain 1 g acceleration to an external observer, and would reach a point where that is simply impossible to do. But that is pointless, as you would want to maintain a 1 g acceleration in a local frame, and that would require a constant amount of power (or less, as you shed mass from using up fuel).

Re:Could we achieve 1G of thust. (0)

Anonymous Coward | about 10 months ago | (#44121433)

I suspected that with a constant acceleration of 1G you'd reach lightspeed before you'd get to Mars. Turns out I was wrong, or I'm bad a physics.
By my calculations you'd be at Mars within 2 days. Your speed would peak at 275km/s, that's (just) 0.00251c.

1G of thust - you're gonna need a bigger boat (5, Informative)

Overzeetop (214511) | about 10 months ago | (#44121607)

1G of thrust would require, as you mentioned, almost 10m/s2 of acceleration, or your mass x 10 in Newtons.

NEXT produces 236 mN of thrust at 7kW of power

A typical terrestrial nuclear power plant will produce about 1 GW of power, or enough to power 143,000 of these engines. That would result in 33,700 Newtons of thrust, able to accelerate a spacecraft at 1G weighing 3433kg.

To put that into perspective, those (143,000) engines would burn 2860kg/hr in fuel alone.

Re:1G of thust - you're gonna need a bigger boat (0)

Anonymous Coward | about 10 months ago | (#44121819)

Increase v of the ions.

Re:1G of thust - you're gonna need a bigger boat (0)

Anonymous Coward | about 10 months ago | (#44122107)

The ion engine already makes the ions move very fast. That is why ion engines like this one are so efficient. I'm sure NASA would love to make the ions go faster, but it's easier said than done.

Re:1G of thust - you're gonna need a bigger boat (1)

Impy the Impiuos Imp (442658) | about 10 months ago | (#44122411)

Yes, the article mentions 90,000 kph of the ions. Compare vs. what, maybe a few kph for chemical rocket exhause? The obvious difference in reaction mass speed shows tremendous relative efficiency.

The real gem will be in a future accelerator that can do a noticeable fraction of the speed of light.

Re:Could we achieve 1G of thust. (1)

denis-The-menace (471988) | about 10 months ago | (#44121639)

Even a level of trust that can help a satellite/ship leave an asteroid would be useful.

After that, a level of trust that can make a ship escape the gravity of the moon would be very useful.

Re:Could we achieve 1G of thust. (1)

ebh (116526) | about 10 months ago | (#44122897)

"Level of trust"? Is that anything like John Glenn's quip about sitting on top of two million parts, all built by the lowest bidder?

Re:Could we achieve 1G of thust. (2)

MrChips (29877) | about 10 months ago | (#44121705)

At 1g accel/decel you could get to Mars in about 24 hours. At 1/3g it would be about 48 hours. And for those who want to approach the speed of light, that would take a year at 1g.

Re:Could we achieve 1G of thust. (0)

Anonymous Coward | about 10 months ago | (#44123055)

The delta-V needed to fly a 1g brachistochrone to Mars is freakin' ridiculous. A nuclear saltwater rocket might be up to the challenge, maybe. Heck, even doing that flight at 0.1g would be a heck of an accomplishment.

Fools! (5, Funny)

Anonymous Coward | about 10 months ago | (#44121225)

Running that engine for 5 years attached to the planet already caused a diversion of 0.01 on the orbit we have around the sun! That's why the sudden global warming! Tin foil ionic hat

Re:Fools! (0)

Anonymous Coward | about 10 months ago | (#44121555)

So far as I can tell from the pictures, the engine was mounted horizontally, so it would only have an effect on the rotation of the Earth, not its orbit. (I doubt it had any effect on global warming.)

Re:Fools! (0)

Anonymous Coward | about 10 months ago | (#44121609)

More rotation = more magnetic shielding from solar winds... we should have a global cooling.

Re:Fools! (0)

Anonymous Coward | about 10 months ago | (#44121635)

And at any rate you're missing a dozen zeroes after the decimal point.

Re:Fools! (4, Informative)

burisch_research (1095299) | about 10 months ago | (#44121765)

Bzzt you are both wrong. The net acceleration due to this test is zero, because the ions ejected out of the engine are halted by the test chamber. Net result is zero force.

Re:Fools! (1)

L4t3r4lu5 (1216702) | about 10 months ago | (#44122055)

Nope. They pointed it straight up, meaning all that happened was the desk now has a dent 1x10^-9m deep where the bracket was, and someone on the floor above got a slightly warm bum.

How Fast? (2)

Rob Riggs (6418) | about 10 months ago | (#44121313)

If you had one of these on a spacecraft like Voyager with 1000kg of fuel running for 50,000 hours, what does that acceleration translate to in terms of velocity, assuming an initial velocity after launch of something like 40,000km/h?

Re:How Fast? (0)

Anonymous Coward | about 10 months ago | (#44121537)

Maximum speed 90,000 mph.

By Newton's law: f = m a, solve for a: a = f / m.
Plug in the numbers:
a = 0.092 N / 1,100 Kg
gives us an acceleration of:
a = 8.8 x 10^-8 meters per second per second

  ???

Re:How Fast? (1)

Overzeetop (214511) | about 10 months ago | (#44121551)

Well, NEXT produces 236 milliNewtons of thrust, according to this article: http://www.newscientist.com/article/dn12709-nextgeneration-ion-engine-sets-new-thrust-record.html#.UcxBsfmcf4o [newscientist.com]

NEXT + nuclear reactor ~ 5000kg* (wag)
Fuel 1000kg
Voyager = 722kg

If we take our mass as an average to simplify the math, and ignore relativity (which I'm betting we can),
6222kg avg mass at 0.236N is 4.22x10-5 m/s2 acceleration. And for 50,000hx3600s/h = 7600 m/s delta V
So in 6 years, we will have accelerated from 11,100 m/s to 18,700 ms, or from 0.000037c to 0.000062c

People may say physics is a bitch, but based on these numbers, it looks more we are physic's bitch. (insert Soviet Russia joke here).

*a goal in the above article is to create a small, portable reactor of 5Mg to produce 40kW, which would actually power almost 6 of these thrusters. For the sake of argument I scaled it down to 4Mg to allow for 1Mg of thruster and fuel tank hardware, but that's still a pretty wild guess.

Re:How Fast? (0)

Anonymous Coward | about 10 months ago | (#44121651)

18700 meters / second = 41830.7087 miles / hour

Re:How Fast? (0)

Anonymous Coward | about 10 months ago | (#44121933)

The mass is constantly changing, so you actually have to integrate to account for the loss of reaction mass due to the engine firing Xenon out the back and into space.

Re:How Fast? (0)

Anonymous Coward | about 10 months ago | (#44121647)

DeltaV = V_exhaust * ln (m_0 / m_1)

V_exhaust for a NeXT is about 145,000 km/h.

Say two tonnes of spacecraft and one tonne of fuel.

145000 * ln(3/2) = 58792 km/h of delta V from the NEXT thruster. That is a huge delta V by any standard, and incredible for a craft that's only 33% fuel.

Re:How Fast? (3, Funny)

JTsyo (1338447) | about 10 months ago | (#44121667)

F=ma
.236 N = 1000 kg * a
a = .000236 m/s^2

V=V0+a*t
V=(40,000 km/h)/(3600 sec/hr) + (.000236 m/s^2)*(50000 hours *3600 sec/hr)
V=53,591 m/s => 192928 km/hr =>0.00018 c

How fast would it be going? (2)

complete loony (663508) | about 10 months ago | (#44121413)

So, if they had launched it into space, how fast would it be going after all this time? And would it still be receiving enough energy from the sun to maintain that level of thrust?

Re:How fast would it be going? (1)

Anonymous Coward | about 10 months ago | (#44121559)

Missions with that kind of planned range and duration generally don't have solar panels, because the sun is so faint where they're headed (even at the orbit of Mars, solar flux is less than half of that on Earth). Instead, they use radioisotope thermoelectric generators -- a lump of radioactive metal creates heat as it decays, which the spacecraft converts to power via thermocouples.

Distance estimate (1)

Anonymous Coward | about 10 months ago | (#44121489)

I think I've calculated this correctly - assume this was bolted to the back of a spaceship in 0g, and the whole unit weighed 2000kg and not accounting for weight decreasing over time as propellant burns, how far would you get? Assuming constant acceleration for the first half of the trip, constant slowing for the second.

7500kW = 2000N / a
a = 3.5m/s^2
t = 48000hrs / 2 = 86400000s
c = 299792458 m/s
d = (c^2/a) * (sqrt(1+(a*t/c)^2) - 1)
      = 10794747340804852 = 1.14ly

So 1.14ly before you turn the thruster around to slow, and you've traveled 2.28ly after 5.5yrs.

Am I right? Does a career in space engineering beckon?

PS. What, STILL no Unicode in comments? Hi, Slashdot, it's been around for at least 20 years - move with the times, grandad.

Re:Distance estimate (0)

Anonymous Coward | about 10 months ago | (#44121547)

Please excuse my extraneous SI prefix - output is 7.5kW or 7500W, not 7500kW.

Re:Distance estimate (3, Insightful)

abies (607076) | about 10 months ago | (#44121617)

Don't know where you got these numbers from, but:
- There is no way this ion engine can produce 0.3g acceleration on 2000kg probe; something is way off.
- in addition to propellant, ion engine requires power - a lot of power ; you need to add weight of nuclear reactor on top of that (which is probably only thing able to produce enough power for long term with small amount of consumable fuel); for 2000N you would need something like 50MW of constant power supply

But yes, if you can create imaginary engine giving you even 0.1g of constant acceleration for spaceship over period of few decades, entire galaxy is yours.

Re:Distance estimate (0)

Anonymous Coward | about 10 months ago | (#44122467)

Well.. everything within 1-200 light years. Beyond that it gets to the point of diminishing returns or you're just sending people off, never to see or hear from them again. The milky way is 100,000 light years. Even with this happy imaginary spaceship travelling at c, it would take almost the age of humanity to go from one side to the other and back.

Re:Distance estimate (1)

abies (607076) | about 10 months ago | (#44122735)

Not for the people on spaceship - and you care about them, not Earth. You can colonize the galaxy, you just cannot exploit settlers afterwards.
http://einstein.stanford.edu/content/relativity/q917.html [stanford.edu]

0.9c 2.29
0.99c 7.08
[...]
0.999999c 707.1
0.9999999c 2236.0

Of course, at high speed you will get problems with acceleration... fortunately, your fuel will get heavier as well. It all depends on that imaginary, perfect 0.1g engine which can sustain it even at close-to-lightspeed pace.

Re:Distance estimate (0)

Anonymous Coward | about 10 months ago | (#44121713)

Does a career in space engineering beckon?

Hopefully not, but sadly it wouldn't be the first time someone f'ed the calculations at NASA.

Re:Distance estimate (1)

burisch_research (1095299) | about 10 months ago | (#44121911)

Something is seriously wrong with your maths here. Don't quit your day job.

Thruster = 0.000236 N
Mass = 2000
f=ma ; a=f/m=0.000236/2000=1.18e-7 (this is a VERY low acceleration)
s=ut+(1/2)at^2 (u=0 so we ignore that part)
assume t=24000 hrs=2e9 seconds (to turnaround point)
s=0.5 * 1.18e-7 * 2e9 * 2e9=2.360e9 metres
By turn-around you would have travelled 2.36 million kilometres.
1 light year is 9.461e15 metres, so the space craft would have travelled about 2.5 millionths of a light year.

We all know what comes next. (1)

gallondr00nk (868673) | about 10 months ago | (#44121695)

All we need is two of those engines, a spherical cockpit, and two large solar panels attached to each side.

Re:We all know what comes next. (0)

Anonymous Coward | about 10 months ago | (#44122221)

All we need is two of those engines, a spherical cockpit, and two large solar panels attached to each side.

Darth Vader's space car?

Re:We all know what comes next. (0)

Anonymous Coward | about 10 months ago | (#44122713)

|-o-| or the more fancy (-oO-)

NASA should come clean (1)

bitt3n (941736) | about 10 months ago | (#44122245)

it's time for NASA to admit they locked the keys inside the thing, swallow their pride, and call AAA

NASA's NASA (NASA's Acronym Standard Acronym) (0)

Anonymous Coward | about 10 months ago | (#44122353)

Tautologically speaking, I say this is redundant.

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