Space proplusion that needs no propellant, really.

[SerScot]

Here's the article:

www.techtimes.com/articles/11977/201408 ... travel.htm

From the article:

Cannae drive technology, a way of propelling spaceships using microwave energy, has been successfully tested by NASA. Such an engine, if thoroughly developed, could shorten the time needed for a trip to Mars from months to weeks. The biggest surprise of the test was that the system worked at all -- theory said the engine would not be able to produce any amount of thrust -- even the small amounts of power seen in the test.

The experiment involved filling a specially-designed container with microwaves. The uneven shape of the canister creates a difference in radiation pressure, causing a thrust forward, toward the larger end of the vessel. Despite what most physicists predicted, the device started to produce a small amount of thrust, slightly over 0.0001 ounces.

That amount of force is not large, but just the fact that any at all was measured baffles scientists. The conservation of momentum states that no thrust at all should be produced by such a system.

A pair of Cannae drives were produced for the tests. While one was built according to its design, the other was purposely manufactured to fail. Investigators were shocked when each of the drives produced a net thrust.

This is huge. How much easier is interplanetary travel if you don't need to strap huge propellant tanks to your ship. Lower mass lower inertia. Spacebourn travel may be getting much cheaper.

Hopefully, they can do something with this in my lifetime.

[rdhopeca]

I am following this with much interest. I love the idea. As long as defying Newtonian physics doesn't come with some sort of health side effects.

[SerScot]

It will not get us out of the depths of the gravity well, but, once in orbit... very interesting things become possible.

[I'm Murrin]

If it is indeed pushing off from particles in vacuum as I've seen suggested, it might turn out to not actually be violating Newton's laws. It remains to be seen how this is actually working, though.

[Hashi Lebwohl]

I want to say that this sort of drive was proposed and tested some years ago but everyone laughed at it and called it pseudoscience and claimed that the researchers were fudging their numbers in order to attain the desired results but I doubt I will be able to recall where I read it so I could link it.

Still....once a drive like this gets built and put into orbit even if it produces only .05g that is still 0.49 m/s^2 so after only one hour you are going 176.4 m/s but after 6 hours you are cruising along at 10.58 km/sec, a decent speed. Even then, it will still take you about 3 months to reach Mars, maybe 4 months after accounting for course corrections and having to catch up to the planet...presuming you didn't launch so that Earth and Mars were aligned so that Mars is approaching you.

Of course, the current drive doesn't produce anywhere near that amount of acceleration and a feasible Mars mission needs to reach its destination in less than a year. If this drive, once tested and the design gets upgraded, can produce even 0.15g then Mars becomes an actual possibility.

[I'm Murrin]

The article I read about it mentioned that - there was a very similar engine a little while back that was tested by its inventor and then a Chinese group, but people doubted the results. This new one was the third independent test to produce a positive result from this kind of propulsion (albeit a different design), which is why it's gaining traction. There's still doubt, because the Chinese announced much bigger results than this new test.

[SerScot]

Oh, come on, have we no skeptical physicists or engineers who will decry this potentially world altering new technology?

[Vraith]

Oh, come on, have we no skeptical physicists or engineers who will decry this potentially world altering new technology?

Heh...I haven't gotten into this, but I'm a doubter.
In fact, more than that.
I think it's as true as the cold-fusion in a bottle thing. Which is why we all have cold-fusion reactors in our basements.

[SerScot]

Vraith,

I think we problably don't understand what we have yet but if we have three different tests with similar results that seems pretty promising. It may force us to revisit our underlying assumptions as Lord Kelvin did when it was shown that Atoms actually existed.

[Hashi Lebwohl]

The amount of force generated barely registered but I suspect that was because it was in a lab here on the surface of the planet. Get one of these up into micro-g and test it again. Even 1 mm/s^2 sustained for a couple of hours would be sufficient to convince me of the system's ability to produce thrust.

[SerScot]

Okay, there have been three tests that show this works. How many tests will be needed before people accept that this is a real possiblity as breakthrough technology?

[I'm Murrin]

Well, they are now saying it was probably experimental error, so...

[Hashi Lebwohl]

Which is why it should be tested in micro-g orbit. Send it up, move it into a position so that it is stationary relative to some other object (or group of objects), then turn it on. It should be clearly obvious that it is working in only a few minutes if the propulsion test begins to pull away from the other objects and anything else which could have been moving it has been ruled out.

[I'm Murrin]

Why do you think they couldn't measure the force in a lab?

[Wildling]

Why do you think they couldn't measure the force in a lab?

Gravity and/or friction too much to overcome for such a tiny repulsive force.

That's my theory.

[I'm Murrin]

They don't need the device to move, just to measure a force. I'm sure they have instruments sensitive enough for that.

[Wildling]

I'm not even close to being a scientist. Just seemed like it made some sense.

[Hashi Lebwohl]

The article quoted 0.0001 ounces of force. I am certain there are accelerometers which can measure that accurately but the room in which the measurements are being taken would have to be airtight and not have anything moving in it so that the measurement cannot be attributed to air currents.

I am not saying they didn't get a measurement or that the results aren't reproducible. What I am saying it that we should test it in an environment where we can rule out false readings due to the motion of air or fluctuations in the local gravity. Of course, in orbit you need to be able to filter out solar wind but a simple opaque barrier should suffice for that.

[SerScot]

Murrin,

They did measure force with a very sensative insturment. What Hashi is saying is that puting and object into orbit and manuvering it with this device would put to rest, once and for all, whether this device does what people are claiming it can do.

[Vraith]

It's a jabberwocky. [literally...part of the explanation is nonsense words. A cal-tech physicist: “There is no such thing as a ‘quantum vacuum virtual plasma, There is a quantum vacuum, but it is nothing like a plasma. In particular, it does not have a rest frame, so there is nothing to push against, so you can’t use it for propulsion"]

Seriously, peeps: part of the "test" was a "drive" intentionally built NOT to work, and IT WORKED ANYWAY.
Among other things, that fact itself screams that something is wrong with the test.

There are a number of other problems.