Nasa validates 'impossible' space drive created by British scientist Roger Shawyer

[editor]

I'm sure there's a thread somewhere for this, but I searched for EmDrive and Shawyer and couldn't find anything, so here goes:

EmDrive is a highly efficient propellant-less propulsion system that converts microwave energy into thrust inside a sealed chamber. Such a system would be a complete game changer in spaceflight; it could dramatically cut the cost of satellites and space stations, extend the lives of spacecrafts and drive deep-space missions. But there’s a problem- it violates Newtonian laws of physics, in particular the law of conservation of momentum. Critics have therefore claimed that any thrust generated by prototype systems tested so far must be coming from another source.

Despite supposedly being impossible, the work has sparked genuine interest in some. For example, Chinese scientists have independently and repeatedly proven the theory of EmDrive. Just last year in fact, a Chinese team built their own EmDrive and confirmed that it produced 720 mN of thrust, which would be sufficient for a satellite thruster. This system could be powered by solar electricity, negating the need for a bulky propellant. However, the work was largely ignored and scientists were still far from convinced.

Read more at http://www.iflscience.com/technolog...sible-space-travel-engine-could-actually-work

Nasa is a major player in space science, so when a team from the agency this week presents evidence that "impossible" microwave thrusters seem to work, something strange is definitely going on. Either the results are completely wrong, or Nasa has confirmed a major breakthrough in space propulsion.

British scientist Roger Shawyer has been trying to interest people in his EmDrive for some years through his company SPR Ltd. Shawyer claims the EmDrive converts electric power into thrust, without the need for any propellant by bouncing microwaves around in a closed container. He has built a number of demonstration systems, but critics reject his relativity-based theory and insist that, according to the law of conservation of momentum, it cannot work.

According to good scientific practice, an independent third party needed to replicate Shawyer's results. As Wired.co.uk reported, this happened last year when a Chinese team built its own EmDrive and confirmed that it produced 720 mN (about 72 grams) of thrust, enough for a practical satellite thruster. Such a thruster could be powered by solar electricity, eliminating the need for the supply of propellant that occupies up to half the launch mass of many satellites. The Chinese work attracted little attention; it seems that nobody in the West believed in it.

However, a US scientist, Guido Fetta, has built his own propellant-less microwave thruster, and managed to persuade Nasa to test it out. The test results were presented on July 30 at the 50th Joint Propulsion Conference in Cleveland, Ohio. Astonishingly enough, they are positive.

The Nasa team based at the Johnson Space Centre gave its paper the title "Anomalous Thrust Production from an RF [radio frequency] Test Device Measured on a Low-Thrust Torsion Pendulum". The five researchers spent six days setting up test equipment followed by two days of experiments with various configurations. These tests included using a "null drive" similar to the live version but modified so it would not work, and using a device which would produce the same load on the apparatus to establish whether the effect might be produced by some effect unrelated to the actual drive. They also turned the drive around the other way to check whether that had any effect.

http://www.wired.co.uk/news/archive/2014-07/31/nasa-validates-impossible-space-drive

 

[farmerbarleymow]

That sounds interesting, and hope it leads to better propulsion systems.

But I won't be satisfied until they develop warp drive.

 

[Crispy]

They've validated nothing. The control (ie inert) experiment produced the same result as the trial. The result is due to the surrounding apparatus, not the device.

 

[slainte]

http://jalopnik.com/the-painful-truth-about-nasas-warp-drive-spaceship-from-1590330763

 

[slainte]

hmm.. you never know

 

[Crispy]

http://jalopnik.com/the-painful-truth-about-nasas-warp-drive-spaceship-from-1590330763

Unrelated story. The OP is about propellentless propulsion. The Alcuberrie Drive is a theoretical faster-than-light drive.

 

[beesonthewhatnow]

I'm with the laws of physics on this one I'm afraid.

 

[Crispy]

I'm with the laws of physics on this one I'm afraid.

That's not a watertight argument. There are gaps in our knowledge, and it's possible that there truly is a method for accelerating an object without reaction mass hiding in those gaps. Nobody's found one yet, though.

 

[beesonthewhatnow]

That's not a watertight argument. There are gaps in our knowledge, and it's possible that there truly is a method for accelerating an object without reaction mass hiding in those gaps. Nobody's found one yet, though.

Never say never, obviously. But it's likely that certain unbreakable foundations must exist and this seems to be as good a candidate as any.

 

[Santino]

Fairly sure that Guido Fetta is a character in the new Star Wars film.

 

[Lord Hugh]

That's not a watertight argument. There are gaps in our knowledge, and it's possible that there truly is a method for accelerating an object without reaction mass hiding in those gaps. Nobody's found one yet, though.

Solar sails? Do the photons exerting pressure in those constitute reaction mass?

 

[Crispy]

Solar sails? Do the photons exerting pressure in those constitute reaction mass?

Solar sails don't use photons, they use the solar wind, which is a stream of plasma from the sun (it also blows the tails of comets into their shapes). They are a "propellentless" propulsion system with two major drawbacks: You can only gain thrust in one direction - away from the sun - and the available thrust decreases with the square of your distance from the sun.

The EM drive, if it exists, is practically magical. All you need is a source of constant power (a nuclear reactor, say) and you can accelerate to any speed, limited only by the friction of the interplanetary/interstellar medium. The thrust is miniscule, but it all adds up.

 

[Lord Hugh]

Solar sails don't use photons, they use the solar wind, which is a stream of plasma from the sun (it also blows the tails of comets into their shapes).

You seem to be thinking of magnetic sails, rather than solar sails: https://en.wikipedia.org/wiki/Magnetic_sail

Solar sails do use photons, the blue body impacting in the diagram here is a photon:

Same principal as magsail though, it's just a different particle impacting.

Let's hope something comes out of the EM drive anyway! (but I think it won't, these sorts of magical things always seem to be marred by some experimental flaw which induces the amazing effect being touted)

 

[Crispy]

Thanks for putting me right

Speaking of magnetic sails, I came across a very intriguing re-entry concept that's being tested right now: http://www.nasa.gov/offices/oct/early_stage_innovation/niac/2012_phase_I_fellows_kirtley.html

Basically you use a (moderate, easily generated with regular spacecraft power supplies) magnetic field to trap a bubble of diffuse plasma, 10x the radius of your spacecraft. Then you use that bubble of plasma as a "brake" against the diffuse upper atmosphere. All the absorbed kinetic energy goes into the plasma, not the spacecraft. Someone on the nasaspaceflight forums did the sums and reckons you'll be able to slow down to subsonic speeds before the atmosphere gets thick enough for frictional heating. It would entirely remove the need for thermal protection systems, which is great for re-usable spacecraft, but even better for interplanetary probes, which could double the mass of useful payload.