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Sunday, September 11, 2016
Current Affairs ... Science ...

I’m in the mood for another science post right now, so . . . what to talk about? OK, maybe space exploration. NASA had a good rocket launch this past Thursday of the OSIRIS-REx spaceprobe, which hopes to fly out to a big asteroid called Bennu and grab a small sample of rock or dust or whatever from its surface. If all goes well, OSIRIS-REx will return this sample to earth in 7 years. It will take OSIRIS-REx about 2 years to reach the asteroid, which orbits the Sun in the space between the Earth and Mars.

It takes a long time for spaceprobes to get anywhere in the Solar System. We don’t have rockets big enough to launch a probe with all the heavy-weight scientific do-dads that you want it to have, and at the same time give it enough fuel to keep on accelerating towards its intended destination. Most long-distance probes, including OSIRIS-REx, have to loop back towards the Earth over the first few months of its flight so as to get a “fly-by” boost from the Earth’s own gravity. This is in ingenious way to get the speed needed to sling a spacecraft out of the Earth’s neighborhood, but it sure makes the flight take a long time.

NASA and other nations and organizations concerned with sending space missions across the Solar System would love to have a light-weight method of continually accelerating a spacecraft after we launch it into space, so long as it doesn’t use much power and thus won’t take up a lot of room and weight for extra fuel or batteries. Even if the thrust amount was tiny, so long as it was continual it would gradually build up speed in the probe, faster than a loopy fly-by could do. You could cut off a number of months, maybe even more than a year, from a mission like OSIRIS-REx, if you could tack such a device on it (again, so long as it didn’t significantly add to the size and weight of the spaceprobe).

That’s why there has been so much buzz in the last few weeks amidst the space-heads and with interested physicists in general, regarding a possible way of doing exactly what I just described. The new “device” is generally know as “EM Drive“. The more precise name is “radio frequency resonant cavity thruster“. I’m not going to try to explain precisely what this is and how it supposedly works, but it has to do with microwave generation, using the same kind of “magnetron” that’s inside the microwave oven right there in your kitchen.

Your own microwave oven creates and shoots microwave photons (which are really just a higher-frequency, higher-energy form of light, akin to radio waves or x-rays) into a cavity . . . i.e., the inside of the oven. But you couldn’t just attach a Samsung or GE oven on the back of a spaceprobe and turn it on high. The cavity in question has to have a special design, which looks surprisingly like the cone-shaped thruster bells on the bottom of most rockets including the Space Shuttle. Unlike a thruster on an Atlas or Delta (or a SpaceX Falcon 9; sorry to hear about that explosion that wrecked a Falcon 9 and some communication satellites the other day, including a satellite meant to help Facebook spread its message to the deepest corners of Africa, sort of like the Christian missionaries of days past), the EM drive cone has a metal plate at the bottom of it. Thus, the EM drive is not shooting anything out the bottom to create thrust; there’s no burning rocket fuel nor even energy pulses streaming out (the microwaves get bounced back into the inside of the drive by the bottom plate).

So, how the heck does this device push anything forward, while it’s out in space? Good old Newtonian physics say that for every action, there’s an equal and opposite reaction. For the usual rocket, the action is that the burning fuel shoots out the back of the thruster; and the equal and opposite reaction is that the thruster, along with the rocket that it is attached to, goes forward. But this darn thing isn’t shooting anything out the back, not even some kind of radiation or magnetic fields. It’s similar to the way that you are safe when standing next to your microwave oven when it’s running (so long as the door is in good shape and is properly closed). So how the heck does this fancy version of a cone-shaped microwave oven start pushing anything forward?

A lot of scientists have been skeptical about the EM drive. They say that it DOESN’T push anything. They whole thing, they say, is just some snake-oil from a handful of engineers and money people who allegedly put something together to make a fast buck. The whole idea actually started in 2001 with a British aerospace engineer named Roger Shawyer. Most scientists dismissed him right away, but some didn’t, and the British government gave him a small grant to build a prototype. The idea was never completely verified, but it wasn’t disproven either. Different tests kept coming up with interesting results that hinted that actual thrust was being developed. Before long, various universities, speculative investors, and the Chinese got interested (despite the ongoing criticism and disbelief of the scientific mainstream).

Shawyer stayed involved and has formed a corporation (SPR Ltd) to develop the EM Drive. And not just for NASA space missions; he’s talking about really visionary stuff right here on earth, including flying cars!! But a lot of technical people remain skeptical, especially of flying cars.

Personally, I don’t think that my next car is going to be microwave powered. BUT, as far as space exploration goes, EM Drive did get a boost recently from the rumor that NASA scientists from its “Eagleworks” cutting-edge laboratory are about to have a peer-reviewed article published in a respected scientific journal reporting that their careful tests show that an EM Drive can create thrust. The article is not out yet, but if the rumor holds up, this would be the first peer-reviewed scientific acknowledgement that the EM Drive seems to work. However, the NASA tests supposedly don’t show very much thrust effect. So don’t hold your breath waiting for flying cars. But if this technology does turn out to be legit, then in a few years NASA might be able to speed up its long-range Solar System probes.

Most importantly, if EM Drive is developed and optimized, it might play a big role in the eventual manned mission to Mars, which could happen in the 2030’s (probably after I’m gone). One of the biggest challenges for such a mission is that you have to pack enough water, air, food and energy sources to keep a handful of people alive for several years. If an EM Drive could cut the transit time each way from 9 months to 3 months or less, you knock a whole year off the mission — a huge savings. The whole thing becomes a good bit more do-able (although I still probably won’t live to see it, given how long the idea of going to Mars has been around, and all the political and technical issues that have delayed it).

So, it’s no wonder that NASA is willing to ignore the nay-sayers and keep working on the EM Drive idea. There is an interesting footnote to this, however; supposedly NASA will NOT be the first to actually test an EM Drive in space. Another engineer, Guido Fetta, is the CEO of Cannae Inc. and the inventor of the Cannae Drive, a copy-cat of Shawyer’s EM Drive (i.e., it also qualifies as an “RF Resonant Cavity Thruster”), is about to do it. Mr. Fetta recently announced that he has built a miniature “cube satellite” which contains his Cannae Drive. His company has formed a partnership with other investors, who hope to pay for a commercial launch of his cube satellite in 2017 (cube satellites are becoming very popular, and the cost of launching a briefcase-sized satellite is now coming down under $100,000). If the microwave closed-cavity drive actually works on Fetta’s mini-satellite, it will stay up in orbit longer than otherwise expected. That will be the test. Supposedly Shawyer and the Chinese are also planning satellite tests within the next year or so. NASA will be watching closely, no doubt.

I personally think this is pretty exciting. But before I close here, let me mention that if the EM Drive really does work, physicists right now aren’t quite sure why it does. A physicist named Michael McCulloch from Plymouth University recently published a paper speculating that the EM might work based upon an admixture of Einstein relativity effects and quantum physics effects, known as Unruh radiation.

Very simply (overly simply), Unruh radiation is an effect on any massive thing undergoing acceleration, i.e. being pushed by a force, such that the thing gets a little bit hotter than it otherwise should by general mechanical forces (e.g., if you floor your car’s gas pedal and start screaming down the highway, you and your car will heat up from the engine working, from tire friction, and from air resistance; but due to Unruh radiation, you will heat up just a tiny, tiny bit more because of some quantum and relativity effects). Recall that quantum effects are ultimately digital; they happen in a set amount or not at all, no in-between. That’s what quantum physics is ultimately all about.

Somehow, don’t ask me to explain, in a properly designed EM Drive with just the right amount of microwave energy and with just the right amount of external acceleration (an initial push from something other than the microwaves), the quantum effects on the microwaves will will line up in the drive mechanism such that they all “happen” in one spot, as opposed to the usual mix of happening and not-happening all over the place. This supposedly gives the microwave photons a bit more energy and momentum at one end of the device versus the other. And this quantum-caused energy imbalance then becomes an accelerating force, i.e. “thrust”. It doesn’t really create energy out of nothing; that’s still not allowed. You still need to have a battery or something to power the magnetron that creates the microwaves. But you could then use these fancy quantum tricks to start moving the microwave device, as if putting some aluminum foil in the right places inside your microwave oven could get the thing to hover in mid-air when you start it with the “high” setting.

This would be a nice little trick on Mother Nature, if the EM Drive actually works!! Stay tuned, we may soon know. But as to a hovering microwave oven, or a flying car, or even the speeded-up manned trip to Mars . . . ain’t happening anytime soon.

◊   posted by Jim G @ 8:05 am      
 
 


  1. Jim, This comment is even worse than the last chemistry one was, as far as I’m concerned. I just don’t understand any of it. And I mean ANY of it. So this comment will probably be about all the things I just don’t get that you talk about here­­or maybe the one or two things I don’t get. The rest are REALLY over my head.

    One thing that is always a “strange thing” to me is this point about scientists using the “earth’s gravity” to get a boost for something to move farther out into space. (I think I’ve got that right.) It seems to me that the earth’s gravity pulls “stuff” into/toward the earth; so how it is used as a boost to get something to move farther out into space makes no sense to me. So obviously, I’m a total failure at even a simple idea when it comes to how things move in space.

    As to all the “microwave” stuff and using microwaves to generate thrust (again, I’m not sure I got this right; but I think I might have it). One thing I’m VERY suspicious of is: I’m almost sure that thyroid cancer I had back in the 1980s and that returned some 15 or 20 years later to be “zapped” by radiation was caused by radiation from the microwave I had in my kitchen. I’m not sure I see microwaves as totally benign. (I was also told the radiation treatment for the 2nd-time-around cancer could cause leukemia, which my sister died from.) Sooooo, I am wary of microwave radiation and what that may cause used as a way to increase thrust in a space probe of some kind containing humans on their way to Mars. (Again, I’m not sure I’ve got that idea straight, but I think I have.)

    Specifically: What are the possibilities of thyroid cancer-causing radiation from this “EM Drive” thingee? Will everybody on board and/or the “robot” sent out come down with cancer or be cancer-causing on its return to earth? As I said: This microwave idea tends to make me a bit wary (even tho I do have a microwave in my kitchen; I tend to stay away from it when it’s being used.).

    Another tho’t: Haven’t we already put an unmanned something or other on Mars? Don’t we know already that Mars, as interesting as it might be to some people, is uninhabitable for humans? I’d say glean every single thing we can know about Mars from the unmanned probes before we start thinking in terms of sending a human (or any other earth-living creature) there. What might humans learn that an unmanned robot would not be able to find out?

    And one last thing that I am woefully lacking in any knowledge of: I’ve never HEARD of “Unruh radiation”; so can’t even ask a question about it that reveals the lack of knowledge I have regarding anything so named.

    And to be sure that I cap my “weird tho’ts” off with a REALLY “weird tho’t”: I also find myself wondering if it might not be possible for beings from some other dimension to be have Mars as their planet of choice. (Well, they could be inhabiting the earth with us already, who is to say?, say I.) What unknown life might we “interrupt” or interfere with should we just decide to go “live” there and “scope out” the place.

    Thus, this comment obviously shows how over my head your post is. I just don’t understand any of this stuff, altho it raises questions in my mind; questions that may make no sense, I admit. But then I wonder: Maybe they do make some sense. It may just be in one’s point of view.

    And you say the “EM Drive” could be developed by 2030 (again, if I understand this correctly); that’s only about 15 years from now; I’d say there’s a big chance you might see it. You might be surprised at what will interest you in 15 years!

    I’m definitely out of my element and over my head with your post. Sorry. MCS

    Comment by Mary S. — September 12, 2016 @ 1:42 pm

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