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Theory

Added: March 5, 2007

You're doing what?

Yes, we are building a 32 foot microwave dish with a 1000 watt transmitter that will send a signal that will be detectable against the background noise of space for over 100 light years. Yes, we have concocted a message format that will be comprehensible to a wide variety of audiences. Yes, we have studied our local region of space and picked out 10 local stars systems with at least one planet to shoot at. Yes, although the inspiration for the project is 99.9% for fun, there is solid science behind it and there is, actually, a microscopic chance of success.

Yes, yes, yes...all this is true.

Why should I care? you might ask.

Since my own motivations are pretty vague on this, I don't really have a good answer for that one. I guess the temporary answer is that you probably will only care if on some vague level you think that its cool. If the idea of some jokers in Oregon building a giant space transmitter in the middle of a field out of 2x4's and a microwave oven and then sending messages to outer space seems interesting, well, then read on. If the above idea just seems silly, or weird or criminal, well then you are free to go, no questions asked. Seriously.

If you are still reading this, I will assume you are intereted, so lets get to the meat of it.

On the surface, the project has several gigantic flaws. Anything to do with deep space takes nation-grade resources, dollar amounts with 9 zeros and large rooms full of engineers. Period. The reasons for this are pretty obvious: 1. The earth is really big, and is surrounded by a massive gravity well that is extremely reluctant to let anything out of its grasp. 2. This pea-soup atmosphere of ours causes an enormous amount friction when anything gets moving at a decent speed. 3. Space is huge, individuals are puny and ridiculous and most of the time can't get the money together for new tires or a haircut, much less a space communications dish.

This is mostly true. Getting anything with any kind of physical mass out of Earth's orbit is impossible without a ton of money. This will likely never change. Nobody is every going to launch a rocket from their yard that will put a satellite in orbit, or take pretty pictures of the earth or go poking around on another planet. Ever. Reasons 1, 2 and 3 above most certainly will put a stop to that type of tom-foolery for the indefinite future.

Luckily for us backyard deep space interstellar microwave communications dish builders, however, electromagnetism and its quirks are in a position to salvage the situation from complete disaster.

Electromagetism: More Forgiving than You Might Think

Microwave radiation is a great thing. Really. It has the double bonus of being immune to both gravity and atmospheric friction. A terrestrial signal with very modest power will shoot out of orbit at full speed after only losing a bit of energy to the suspended water vapor and airborne pollutants. Better yet, once it gets out of Earth's grasp it will be smooth sailing in the frictionless vacuum of space. This makes the task of sending a message 40 trillion miles across the galactic disk muuuuuuch easier. All we have to do is get a signal out of our atmosphere with a decent amount of power and direction (easy, since gravity isn't a problem) and it will zip off happily traveling for decades all by itself.

Signal to Noise

So we know we can get a signal out of the atmosphere and on its way to wherever we point it. Great. The next problem is an issue of power, as in lack of it. The most power that we can put behind this signal in our privately funded glory is a teensy weensy little 1000 watts. Its just not that much. 10,000 watts would be better, 100,000 would be awesome, 1,000,000 would be phenomenal. Unfortunately, reason number 3 above puts the limit at 1000 watts, and that is not going to change anytime soon (see below for the explanation of how even this much juice is a complete miracle).

As our message travels through space it will decay (from micro-imperfections in the calibration of the dish) and slowly fade into the background noise of space. Background noise is not trivial. Despite its peaceful appearance, there is an enormous amount of ruckus out there among the stars. Things are blowing up, or getting ripped apart by black holes or imploding or spinning to fast or undergoing gravity collapse or whatever pretty much 24/7. All this activity really tends clog up the airwaves with non-sentient racket, and the chance of our little signal getting swallowed up in among the general frackas is a serious matter to consider.

To increase our chances as much as possible, we will be broadcasting on the relatively "silent" section of the electromagnetic spectrum residing right around 2.6Ghz in the microwave range. This frequency contains a low amount of background noise from all the galactic goings-on, and our own earthly geeks have concluded that this frequency is the most likely one that the aliens will use if they try to communicate with us. They have calibrated all the earthbound SETI hardware to scan this range looking for intelligent signals. It is also the frequency used for the historic Arecibo transmission in 1974 that sent a 20 trillion watt signal to the M13 star cluster 25,000 light years away. Even at 1000 watts, our signal will be detectable, albeit faintly, against the backdrop of space noise on this frequency, forever.

Yes, forever.

$15,000?

The last problem involved the expense and difficulty in getting a microwave transmission unit that operated even at this utterly minimal level. Initial forays into this world were very discouraging, as the units available were extremely expensive and difficult to obtain.

In the end, Wall-Mart came through with an answer. I was talking with a friend about the project and my difficulties in finding a suitable transmitter, and he said "what about just a regular old microwave from Wal-Mart, those things a frickin powerful. Its true, they are very powerful- emitting a radio signal strong enough to heat up the drink next to you while you are listening. We purchased an oven and after cutting it in half with a sawzall to liberate the microwave unit, did some testing to see what it transmitted. Yes folks, its true: A regular old cheap-crap microwave from Wal-Mart just so happens to transmit on the intergalactic hotline frequency of 2.6Ghz right out of the box. The Wal-Mart solution was also about $15,000 cheaper than a military grade commercial transmission unit, so we are
going with it.

So, there you have it: The basic theory of the project and the main challenges that we had to deal with. Take a look at the sections on The Message: What to Send?, and Choosing Target Stars to get more info on other aspects of the project and what we plan on doing with this thing.

Next: What to Send?


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