by Alexander L. Zaitsev, IRE RAS, RussiaIn 2001, a group of Russian teens from Moscow, Kaluga, Voronezh, and Zheleznogorsk participated directly and via the Internet in composing a Teen-Age Message (TAM) to extraterrestrial intelligence, and in the selection of target stars. Their message was transmitted in the Autumn of that year, from the Evpatoria Deep Space Center. This brief paper describes the composition of that Message.
Two previous interstellar radio messages (IRM), one transmitted from Arecibo in 1974 and the one from Evpatoria in 1999, had digital format and represented binary scans of one (Are) or 23 (Evp) black-and-white stylized images. But one might suppose that transmission of analog IRMs is also possible. So, before composing the message's content (as well as trying to decode future signals from ETI), let us try to determine such a message's possible format and structure.
We can think of three kinds of information which our IRMs can deliver to the proposed addressee: (1) astrophysical characteristics of interstellar medium, (2) our feelings and (3) our thoughts. Thus, section (1) of our IRM has to be a coherent- sounding radio signal, which will give to aliens an opportunity to investigate the interstellar medium by examination of small variations in phase/amplitude/polarization of the received wave. Section (2) of our message has to carry analog information about our internal emotional world. It may be music and other possible displays of Art. Section (3) is well-known digital information as a sum of knowledge and understanding about ourselves and nature.
The spectral approach is a universal tool of both astronomical observations and SETI. Besides, it has a clear physical meaning -- spectrometers find the energy distribution of photons; in human sensing and art, spectra represent color and pitch. Under the hypothesis that physical laws are identical throughout the Universe, it may be proposed that spectrometry is also using by those aliens who know radio and conduct their own SETI activities. Also, in order for them to easily conceive our spectral information, it will be best to present it as a single-valued function of time. An additional argument for such a function is that a transmitter's energy be concentrated in a narrow band, solving for the aliens some of their own SETI problems.
We conceive three types of single-valued functions -- constant, continuous, and discrete. A radio signal with constant frequency and so, with zero initial information content, uses the "language of nature" to report to Them some useful astrophysical data about the interstellar medium. A message with discrete variations can be used to convey the "language of logic", and a continuous one may be used as an instrument to convey the "language of emotions" in order to inform extraterrestrials about our unique inward experiences. Examples of these three signal types appear in this graphic.
We used the idea of such a three-section structure to design of what we've called a Teen-Age Message to ETI. Section 1 of the TAM had a duration of ten minutes and represented a monochromatic radio wave with Doppler correction of the Earth's rotation and motion around the Sun, in order that They would receive the signal with a "constant" frequency. Analog information selected for Section 2 consisted of a 15-min concert, performed on a Theremin musical instrument, which generates optimal waves with minimal levels of overtones, i.e. a single-valued continuous frequency function. There were seven musical melodies selected for this 1st Theremin Concert for Aliens. Digital information in Section 3 contained the binary scans of TAM's Logotype, texts of Greeting to ETI, written both in Russian and English, and an Image Glossary of basic terrestrial concepts.
There were 6 sessions of TAM transmission, on August 29, September 3 and 4, 2001 from 70-m dish of the Evpatoria Deep Space Center, to 6 nearby Sun-like stars, some of which have own planet or planetary system (47Uma). More info about the TAM may be found at these links:
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this page last updated 28 December 2002
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