Fuel Free Spacecrafts Using Graphene

William Robinson writes: While using a laser to cut a sponge made of crumpled sheets of Graphene oxide, researchers accidentally discovered that it can turn light into motion. As the laser cut into the material, it mysteriously propelled forward. Baffled, researchers investigated further. The Graphene material was put in a vacuum and again shot with a laser. Incredibly, the laser still pushed the sponge forward, and by as much as 40 centimeters. Researchers even got the Graphene to move by focusing ordinary sunlight on it with a lens. Though scientists are not sure why this happens, they are excited with new possibilities such as light propelled spacecraft that does not need fuel.

Comments

Can't be fuel-free forever

[Ken_g6]

Instead, they think the graphene absorbs laser energy and builds up a charge of electrons. Eventually it can't hold any more, and extra electrons are released, pushing the sponge in the opposite direction. Although it's not clear why the electrons don't fly off randomly, the team was able to confirm a current flowing away from the graphene as it was exposed to a laser, suggesting this hypothesis is correct (arxiv.org/abs/1505.04254).

He thinks a graphene-powered spacecraft is an interesting idea, but losing electrons would mean the craft builds up a positive charge that would need to be neutralised, or it could cause damage.

So they'd need to carry hydrogen and split off its electrons or something to neutralize the charge.

Re:Obviously

[Anonymous Coward]

Ya...I look forward to the legions of Slashdotters who haven't graduated High School or College second guess people with PhDs and decades of experience in experimental Science.

Even More Thrust

[Roger W Moore]

So they'd need to carry hydrogen and split off its electrons or something to neutralize the charge.

Actually this could provide more thrust. Use sunlight to propel the craft until it has built up a large enough electric charge that the efficiency of the thrust begins to drop (since it will take an increasing amount of energy to expel the electrons from something with a large positive charge) and then introduce a stream of neutral gas into the sponge. This should strip the electrons off the gas and the remaining positively charge ions will then be repelled by the positive graphite and provide even more thrust.

Of course this means that you need to have a fuel source but it's likely to be far more efficient than current rocket fuel plus there it no need for it to be something explosive like hydrogen - you could probably use Xenon which is a noble gas and so extremely inert and so a lot safer.

Re:Even More Thrust

[Baloroth]

Existing ion thrusters already use ionized Xenon for propulsion, so it's definitely a possibility (charge the graphene using this technique, ionize the Xenon and use that to neutralize the graphene, use the Xenon as ion thruster fuel). However, electrons are very nearly massless, so unless they're somehow exciting them with massive amounts of energy, the propulsion from the electrons is unlikely to be significant.

Re:Crookes Radiometer

[xtronics]

Actually, just what I was thinking (today nobody remembers Crookes (I named a cat after him)). Key bit of missing information in the article - how good a vacuum? Really matters. And just measuring a hard vacuum as made fools out of a lot of people.

There are other possibilities - our country paid people to publish false and misleading papers (no - they have not been retracted) . This doesn't even become news IMO until it is published and replicated.

The amount of technology that has been 'borrowed' by the Chinese is mind boggling - unprecedented. Yet it takes a particular kind of culture to understand the technology in a way that lets them synthesize further progress. A lot of the papers I see coming out of China are just 'cargo cult science' - looks like science - but it isn't. It takes a particular set of values - held dear and close to the heart - to do real science.

The grant proposal industry has diluted the quality of papers so that a very small minority represent real science. I would think of this as likely just bad science once again.

Re:Obviously

[fyngyrz]

I wonder if they've weighed the sponges. One possibility is that the sponges are deteriorating in a particular direction, thus engaging in conventional "stuff out one end makes you go the other way" propulsion. And also becoming traditional "will get used up" style fuel in the process. :)

Though it'd be all kinds of awesome if it was creating coherent motion out of energy delivered by photons without wearing out. Now *that* could be a space drive.

Re:Obviously

[Beck_Neard]

The EM drive is pseudoscientific rubbish. Conservation of momentum is a buzzkill and there's no way around it. As for this discovery, one of two things will happen:

1. They will 'discover' that it uses no reaction mass, in which case it can safely be discredited as pseudoscience.

2. They will discover that there is indeed reaction mass involved. Actually that's what it says there in the article: "Instead, they think the graphene absorbs laser energy and builds up a charge of electrons. Eventually it can't hold any more, and extra electrons are released" If this is confirmed it means that you can't run this for very long because you build up a positive charge and you need to balance this by gaining electrons from somewhere (interstellar gas maybe?) or ejecting positive ions.

If electron ejection is happening then it's really nothing new; we've known that electron guns can propel objects in space. This might lead to new, more efficient ways of using that effect, though. Still, I doubt that the thrust is going to be anywhere near useful for, say, a manned spacecraft. It might be extremely useful for satellites and probes.