
Spaceship Engine “EmDrive” Actually Works, Leaked NASA Report Reveals - tempestn
http://www.thedrive.com/news/5904/impossible-spaceship-engine-called-emdrive-actually-works-leaked-nasa-report-reveals
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gilgoomesh
This is now _two layers_ of garbage clickbait.

The article links to:

[http://www.nextbigfuture.com/2016/11/new-nasa-emdrive-
paper-...](http://www.nextbigfuture.com/2016/11/new-nasa-emdrive-paper-shows-
force-of.html)

which links to:

[https://drive.google.com/file/d/0B7kgKijo-p0ibm94VUY0TVktQlU...](https://drive.google.com/file/d/0B7kgKijo-p0ibm94VUY0TVktQlU/view)

which is a year old and basically says "more work is needed to rule out
mundane sources of error like thermal expansion".

If there was a new published paper anywhere, it would be significant but there
isn't. This is just a work in progress with any number of corrections to be
made (NOTE: in 12 months, no one has submitted this leaked paper).

Even if it _does_ work, it's less propulsion than an ion drive.

~~~
mikeash
Your final sentence puzzles me. If it works, then it's new physics. That's
tremendously exciting, no matter how little thrust it produces. Especially
since this is a device built without the slightest clue of how it actually
works, so thrust could no doubt be increased dramatically once there's a good
theoretical foundation behind it.

Of course, the fact that it represents new physics is also why the smart money
is on it being some sort of measurement error.

~~~
Ph0X
I'm confused how this was presented by someone 10 years ago, and with all the
researches out there, no one has yet replicated or refuted his work, and NASA
is the only one doing it... 10 years later?

~~~
mikeash
The supposed effect is so small that it's extremely difficult to distinguish
it from potential confounding forces, like air currents or magnetism.
Sufficiently precise experiments require sophisticated equipment, so not many
researchers can try it. Even with really good equipment, it's hard to tell if
the measured force is real. The work has been replicated and refuted many
times, but never conclusively.

------
MPSimmons
Leaked from fall of 2015. I feel like we've already discussed this since then.

The fact that it works is surprising (and I'm still not convinced until we are
actually in space testing it), but also, 1.2 newtons per megawatt is... not a
lot of thrust. But the fact that it works at all still the shock.

~~~
laurencei
"1.2 newtons per megawatt is... not a lot of thrust"

If I recall the previous conversations correctly - the amount of thrust is
irrelevant, because in space you continually apply that thrust over time, and
eventually reach ridiculously high speeds?

~~~
AnimalMuppet
The amount of thrust is relevant if something like ion drives gives you more
thrust for the same power.

Of course, with something like an ion drive, you're throwing mass out the
back, and eventually you run out of mass. (On the other hand, eventually you
run out of the ability to generate power, too...)

[Edit: The bigger picture is that, for this to work at all, there probably
needs to be some kind of new physics here. If there is, this device probably
only exploits it by accident (no matter how much the inventor may think he
knows what's going on). Once we figure out what the new physics is, newer
devices may be much more efficient.]

~~~
stouset
If you're generating multi-MW in space, you have to do something about all
that heat anyway so I'm not sure this is an improvement over an ion drive.

That said, yes, the important thing is that this potentially indicates new
science, which is exciting. When we understand it, we can likely improve the
efficiency greatly. Assuming the effect is real.

~~~
akiselev
Since there's no drag the thermal system isn't as constrained in space as it
would be for a car or aircraft. If you assemble the final spacecraft in orbit,
all that matters is mass so you can create very high surface area radiators
that are extremely efficient as long as they're a few AU from the nearest star
(or pointed in different direction). It'd probably be as big or bigger than a
solar sail but it would use the sails to emit photons instead of absorbing
them and itd work far from any star.

~~~
stouset
That's actually really clever!

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cottsak
NASA haven't validated this
[http://blogs.discovermagazine.com/outthere/2014/08/06/nasa-v...](http://blogs.discovermagazine.com/outthere/2014/08/06/nasa-
validate-imposible-space-drive-word/#.WCJ2v9WGPOU)

Everyone go back to something meaningful.. like the election :p

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advisedwang
The paper in question:
[https://drive.google.com/file/d/0B7kgKijo-p0ibm94VUY0TVktQlU...](https://drive.google.com/file/d/0B7kgKijo-p0ibm94VUY0TVktQlU/view)

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blakes
The leaked report:

[https://drive.google.com/file/d/0B7kgKijo-p0ibm94VUY0TVktQlU...](https://drive.google.com/file/d/0B7kgKijo-p0ibm94VUY0TVktQlU/view)

------
geuis
Garbage article. Just a clickbait review of the article over at
[http://www.nextbigfuture.com/2016/11/new-nasa-emdrive-
paper-...](http://www.nextbigfuture.com/2016/11/new-nasa-emdrive-paper-shows-
force-of.html).

~~~
BoringCode
Garbage article. Just a clickbait review of the paper over at
[https://drive.google.com/file/d/0B7kgKijo-p0ibm94VUY0TVktQlU...](https://drive.google.com/file/d/0B7kgKijo-p0ibm94VUY0TVktQlU/view)

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mabbo
So, someone more clever than me do the math: Can I take some solar panels, and
a few of these babies and head on over to Mars? Or is this still impractical
given the "micronewtons per kilowatt" levels we're talking about?

~~~
extrapickles
Assuming you and your ship weights 1kg, it would take 9.8 gigawatts just to
get it to hover in Earths gravity.

This is roughly half the solar output of Germany at noon or about the same
energy as the Space Shuttles boosters. Basically, if these engines prove out,
they will only be used in space.

~~~
phs318u
Its only usable outside of any serious gravity wells, e.g. for interplanetary
and possibly intersolar travel. They would replace uses currently postulated
for solar sails. Not sure, but it may also be suitable for use-cases currently
postulated by small ion-thrusters as well (especially where weight is
critical).

~~~
mikeash
It would be useful once you're in orbit, even deep in gravity wells, if you're
patient. For example, a geosynchronous satellite with a drive like this could
be launched on a rocket just big enough to get it to low-Earth orbit, and then
it could gradually take itself the rest of the way. But it won't be replacing
traditional rockets for that initial launch unless it's possible to increase
its thrust by many orders of magnitude, and that initial launch is really the
hardest part of doing space.

------
snarfy
I vaguely remember the inventor's theory on how it worked. It's an artifact of
the speed of light being constant in all reference frames. If there is a
pressure inside the chamber, intuitively the outside net force would be zero.
But with light it's different due to the constant velocity. If the pressure
was caused by little particle bouncing against the chamber walls, their
velocities would counter each other as they bounced the chamber around.
Velocities with light don't add that way.

I may have gotten some of it wrong, but that's how I recall it.

------
highd
Reported thrust to weight ratio is 360 times raw photons:

[http://www.wolframalpha.com/input/?i=(1.2+mN%2FkW)%2F(1%2F(3...](http://www.wolframalpha.com/input/?i=\(1.2+mN%2FkW\)%2F\(1%2F\(300+MW%2FN\)))

I spent a little time evaluation some form of quantum resonant enhancement of
pair production as an explanation, but not enough to make any claims. The
pilot wave / ether theories suggested in the conclusion seem highly unlikely.
I'm also still holding out for weird RF coupling - those Q factors are so
high.

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matt_wulfeck
I love this type of science. It's completely, totally impossible... until we
learn about how it works and the mechanics behind it. Maybe this type of drive
just previews a new discovery?

~~~
greglindahl
For most results like this, it turns out to be an experimental mistake. That's
how the phrase "extraordinary claims require extraordinary proof" came about.

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dnautics
I'll believe it when I see a small spacecraft propelled by it (even if the
entire spacecraft is the engine), but I think it's an experiment that should
(and could) be done soon.

~~~
nwrk
Seem like it's already in motion by USA and China

[http://www.ibtimes.co.uk/space-race-revealed-us-china-
test-f...](http://www.ibtimes.co.uk/space-race-revealed-us-china-test-
futuristic-emdrive-tiangong-2-mysterious-x-37b-plane-1590289)

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Animats
What "leak"? It's on the NASA Eagleworks Facebook page and there's a press
release.[1] NASA has an in-house fringe science operation in case something
actually works.

[1]
[https://www.facebook.com/eagleworksnasa/](https://www.facebook.com/eagleworksnasa/)

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nwrk
Technology presentation:
[https://vimeo.com/channels/Emdrive](https://vimeo.com/channels/Emdrive)

Inventor website: [http://www.emdrive.com/](http://www.emdrive.com/)

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droopybuns
I wanted to understand the context. Does my analogy correctly approximate the
claims?

The power of 100 100 watt bulbs applied towards pushing a 1 kg object 1.2
millimeters.

~~~
tempestn
It says 1.2mN of force per kW. One kW would be 10 100 watt bulbs. So for as
long as you apply that amount of power, you get that amount of force. And
because force = mass times acceleration, your 1kg object would be accelerated
at 1.2mm/s^2 - meaning its velocity would increase by 1.2 millimeters per
second, each second, for as long as the force is applied. So, run it for 10
seconds and then turn it off, and the object would be moving at 12mm per
second, for instance.

That is in absence of any counter-force, such as would be applied by friction
or air resistance. Practically those would overwhelm the tiny force from this
drive, which is why it's only really practical in space.

~~~
droopybuns
Thank you for catching my conversion mistake. Also the helpful description

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anonymousab
I recall that some group was planning to put one on a cubesat and see what
happens.

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ab5tract
Take that, physics!

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kordless
The going theory for why this works involves physics of the ether, something
science has pushed into a corner and forgotten over the last century. Louis de
Broglie would likely be disappointed it took us this long to realize what he
postulated so long ago. I would also note that Faraday was running experiments
late in life trying to dig up some experimental evidence for this hypothesized
force, albeit by dropping bismuth chunks from a tower into a pillow.

[http://www.helsinki.fi/~aannila/arto/emdrive.pdf](http://www.helsinki.fi/~aannila/arto/emdrive.pdf)

~~~
pmalynin
Sorry to crush your dreams bud:

[https://en.m.wikipedia.org/wiki/Michelson–Morley_experiment](https://en.m.wikipedia.org/wiki/Michelson–Morley_experiment)

~~~
kordless
Don't speak for my dreams. I made zero comments regarding whether I think this
is true or not and only provided as much info as I had on it. To have you
comment in this way with some lame ass link is likely a sign of conflict
within yourself.

