Author Topic: Graphene-based Propulsion  (Read 5450 times)

Offline MajorBringdown

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Graphene-based Propulsion
« on: 06/02/2015 03:15 PM »
Here's an article on New Scientist about the potential for graphene as a propulsion source.  Sounds like a solar-sail, but there appears to be more force than what photons themselves would provide.

http://www.newscientist.com/article/mg22630235.400-spacecraft-built-from-graphene-could-run-on-nothing-but-sunlight.html#.VW3HVVzByGt

Offline sghill

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Re: Graphene-based Propulsion
« Reply #1 on: 06/02/2015 04:19 PM »
I saw that too.  Then I saw where the research was being conducted....
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Offline MajorBringdown

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Re: Graphene-based Propulsion
« Reply #2 on: 06/02/2015 07:11 PM »
Is it the researcher in particular, or the university?  Are they known for dubious research?

Offline sghill

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Re: Graphene-based Propulsion
« Reply #3 on: 06/02/2015 07:31 PM »
Look up previous winners of the Maddox Prize and go from there. Or read this Economist article for a good start: http://www.economist.com/blogs/analects/2014/03/rd-china or this one: http://www.economist.com/news/china/21586845-flawed-system-judging-research-leading-academic-fraud-looks-good-paper

The murky Chinese research industry spends more as a percentage of GDP than does the EU.  Chinese research institutions are beset by endemic fraud, unsound research practices, and a naked quest for publishing white papers in order to raise their public profiles in order to bring in more state money for more shady research projects driven by endemic fraud in a "golden triangle" of research-fueled waste.  If they allowed their research to be peer reviewed before making announcements, I'd certainly take a different tone regarding the basic science involved.  And to be completely fair, it is getting better. 

I know I derailed your graphene propulsion thread, but the story was a fantastic announcement from a troubled source with no outside review to falsify the claimed results.

Here is their published research: http://arxiv.org/abs/1505.04254

Excerpt: "It has been a great challenge to achieve the direct light manipulation of matter on a bulk scale. In this work, the direct light propulsion of matter was observed on a macroscopic scale for the first time using a bulk graphene based material. The unique structure and properties of graphene and the morphology of the bulk graphene material make it capable of not only absorbing light at various wavelengths but also emitting energetic electrons efficiently enough to drive the bulk material following Newtonian mechanics. Thus, the unique photonic and electronic properties of individual graphene sheets are manifested in the response of the bulk state. These results offer an exciting opportunity to bring about bulk scale light manipulation with the potential to realize long-sought proposals in areas such as the solar sail and space transportation driven directly by sunlight."

Plus, of course, if light is indeed exciting the graphene to build up and then shed electrons that act a source of thrust as claimed in the article, then a sheet of graphene sitting out in the sun should rapidly build up a mammoth static charge that would be quite noticeable (depending on humidity).  And if this IS true, then we might as well end the photovoltaic industry as we know it right now.

Methinks poor grounding of their equipment is the source of their static thrust.
« Last Edit: 06/02/2015 07:53 PM by sghill »
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Offline Raj2014

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Re: Graphene-based Propulsion
« Reply #4 on: 06/02/2015 09:03 PM »
Here's an article on New Scientist about the potential for graphene as a propulsion source.  Sounds like a solar-sail, but there appears to be more force than what photons themselves would provide.

http://www.newscientist.com/article/mg22630235.400-spacecraft-built-from-graphene-could-run-on-nothing-but-sunlight.html#.VW3HVVzByGt

This is very interesting and I hope they will research this and build a spacecraft that will use graphene as a sail. What I would like to know is, how much thrust did the sponge produce? In the new scientist article, the thrust was lower than a chemical rocket but it was higher than a solar sail.

Offline Hanelyp

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Re: Graphene-based Propulsion
« Reply #5 on: 06/02/2015 09:47 PM »
At least a few of us agree that if the light driven electron emission works, charge buildup is an issue for a thruster.  While there will be some charge neutralization from ambient plasma, the rate of electron collection limits long term thrust.

Offline sghill

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Re: Graphene-based Propulsion
« Reply #6 on: 06/02/2015 10:34 PM »
At least a few of us agree that if the light driven electron emission works, charge buildup is an issue for a thruster.  While there will be some charge neutralization from ambient plasma, the rate of electron collection limits long term thrust.

Yep, but it'd make an amazing solar panel!!
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Offline MajorBringdown

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Re: Graphene-based Propulsion
« Reply #7 on: 06/03/2015 02:23 PM »
At least a few of us agree that if the light driven electron emission works, charge buildup is an issue for a thruster.  While there will be some charge neutralization from ambient plasma, the rate of electron collection limits long term thrust.

Yep, but it'd make an amazing solar panel!!
That doesn't seem entirely out of the question.  Some quick googling turns up a number of results about graphene-based solar cells & panels.  Some of them even appear to come from non-quack sources.

And I don't mind a thread being derailed if it's heading in a nonsense direction anyway, which seems likely based on your previous comment.  Perhaps this can be revisited if/when this idea has been peer reviewed.  It sounds like it would be a fairly straightforward experiment to reproduce.

Offline sghill

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Re: Graphene-based Propulsion
« Reply #8 on: 06/03/2015 02:53 PM »
Well if sunlight is causing a charge build up on the surface, just tape some bare wires across the thing, and you're good to go as a PV source.  Also, because you are using a single molecule- versus silicon chips- to convert sunlight into electric potential, I can even imagine graphene-impregnated paint where you paint it on whatever surface you want, mount some wires onto the surface and harvest the charge for free.  THAT would be a world changing technology.

It'd be inefficient as heck, and need some controllers to make the charge usable, but woah!
« Last Edit: 06/03/2015 02:54 PM by sghill »
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Offline vulture4

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Re: Graphene-based Propulsion
« Reply #9 on: 06/04/2015 04:14 PM »
"The team also ruled out the idea that the laser vaporises some of the graphene and makes it spit out carbon atoms."

Not sure how they ruled this out.  Graphene is extremely light, so very little force was needed to move it. The effect wasn't reported with ordinary sunlight, only with a laser or with sunlight concentrated by a lens. How did they rule out thermal recoil of air molecules from a heated surface, as in a radiometer? How did they rule our vaporization or even oxidative combustion of a very small amount of the carbon? I just don't see how photelectric emission could generate significant force.

Offline dustinthewind

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Re: Graphene-based Propulsion
« Reply #10 on: 07/13/2015 04:16 AM »
I just wanted to post a picture of what might be happening here as it suggest how such light propulsion might be happening.  The idea being what if the graphene is some how turning the energy of light into momentum more efficiently by the kicked electron? 

Offline sanman

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Re: Graphene-based Propulsion
« Reply #11 on: 07/13/2015 05:03 AM »
Perhaps the electronic delocalization from the SP2-hybridized carbon of graphene allows the electron to be ejected more easily without feeling any localized electric field to force it back. Consider how very large that graphene sail would be - that's a lot of SP2 hybridization and a lot of electronic delocalization going on.

Offline dustinthewind

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Re: Graphene-based Propulsion
« Reply #12 on: 07/13/2015 06:33 AM »
Perhaps the electronic delocalization from the SP2-hybridized carbon of graphene allows the electron to be ejected more easily without feeling any localized electric field to force it back. Consider how very large that graphene sail would be - that's a lot of SP2 hybridization and a lot of electronic delocalization going on.

I guess I am still unsure what your getting at.  How would you would separate an electron from the material without it feeling an electric field pulling it back? 

I guess that is why I don't really get their explanation.  They have electrons being kicked in the opposite direction and as if they are never going to come back to the source. 
« Last Edit: 07/13/2015 06:40 AM by dustinthewind »

Offline sanman

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Re: Graphene-based Propulsion
« Reply #13 on: 07/14/2015 02:34 AM »
I guess I am still unsure what your getting at.  How would you would separate an electron from the material without it feeling an electric field pulling it back? 

I guess that is why I don't really get their explanation.  They have electrons being kicked in the opposite direction and as if they are never going to come back to the source.

Electromagnetism (including electric field) has its distance scale range across which it exerts meaningful influence, and beyond which its force has negligible effect. So if electron is ejected ballistically and gets beyond that range, it escapes from the field and isn't pulled back. As charge imbalance builds up, the hurdle of ejecting that electron gets greater, of course. But graphene is SP2-hybridized carbon, which has electronic delocalization (aka. aromatic resonance stabilization), which allows a kind of special orbital sharing that makes it easier to eject electrons. (Sorry, just vaguely remembering university chemistry)
This SP2 orbital hybridization is one of the things that gives graphene all its special properties.

Offline martin55

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Re: Graphene-based Propulsion
« Reply #14 on: 10/26/2017 10:23 AM »
Its certainly a really bold idea. Graphene is certainly material I would go for such a project. It is wonderful material (more) that really never fail to impress me. On the other hand on such a scale and with thickness of only one layer should be very prone to damage from any kinds of particles, stronger solar storms etc. However I really hope they gonna make it work eventually. :)

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