Aliens More Likely to Pick Up Our NEO Radar Transmissions than Radio

Radar emissions - lighting up the night sky (Ian O'Neill)

When you stop to think about it, sending transmissions via radio into space in the hope to contact aliens is a bit silly. The intention behind the 16 transmission we have directed into space is to a) make contact with extraterrestrials, b) advertise our presence in the cosmos, and c) tell ET something useful about mankind. We know we are leaking transmissions into space all the time (i.e. radio and TV), but we assume they don’t travel that far or are too weak for aliens to detect. But wait one second… We are constantly blasting radar into space, tracking near earth asteroids; will aliens pick up those transmissions? Well, these radar transmissions have covered 2000 times more sky than radio and last 500 times longer. And since the 1960’s we’ve sent 1400 radar transmissions into space. So, what’s the verdict? Aliens are one million times more likely to receive the tracking signal from NEO tracking radar than radar intended for aliens…

I don’t usually cover stories like this on astroengine, but it interested me, so I thought I’d share. In a paper recently published, Dr Alexander Zaitsev points out there are three large, high powered instruments on the planet used to analyse asteroids, comets and planets in our solar system. The Arecibo Radar Telescope (ART), Goldstone Solar System Radar (GSSR) and the Evpatoria Planetary Radar (EPR) are also used to message extraterrestrial civilizations as the signal from these huge dishes are thought to be powerful enough to be deciphered anywhere within the Milky Way. But dishes such as these have also been used in radar tracking exercises, observing NEOs or bouncing off other Solar System planets, and for much longer than any alien communication attempt.

Zaitsev calculates the proportion of sky illuminated by these 1400 radar transmissions to be approximately 2×10-3 (that’s a respectable 0.2%). The 16 ET transmissions covered only 0.001% of the sky. Add to this the total time of the radar tracking transmissions were 500 times longer, it seems probable that aliens would have picked up the radar tracking signals way before they receive our communication attempts.

It kinda makes one of my articles on the Universe Today, Are we sending a bit too much information into the cosmos?, a bit void. Why worry about sending messages into space when were doing it by default anyway? This is the main point of this paper – to overcome “METI-phobia“, or the fear of messaging intellegent civilizations. As pointed out by Dr Zaitsev in response to this article, if we have a next-to-zero METI (Messaging Extra-Terrestrial Intelegence), when compared to SETI (Search for Extra-Terrestrial Intelegence), and if we assume other civilizations will have a low METI:SETI ratio, the universe will remain a very quiet place, we’ll all be listening out, but nobody will be transmitting. Why assume alien races will be so noisy?

Still, if aliens are looking for us, our NEO radars might be making enough noise…

Sources: arXiv, arXivblog

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