Classification of Interstellar Radio Messages

During the preparation and transmission of any interstellar radio messages (IRMs), some scientific and technological issues need to be addressed. The paper «Messaging to Extra-Terrestrial Intelligence» (METI) [1] lists nine of such issues. We propose to rank planned and already sent IRMs depending on how well three basic METI’s issues are resolved in them. These basic issues are the following: (1) choice of the target stars, (2) energy required per bit of the information, and (3) availability of a special digital or analog key to allow Aliens to decode our message, [2]. In order to rank IRMs, it is necessary to find out whether there are serious concerns regarding of how these three issues were addressed.

The corresponding analysis shows that to all three criteria mentioned above in the fullest measure satisfy five sent messages:

Arecibo Message 1974:
Cosmic Call 1999:
Teen Age Message 2001:
Cosmic Call 2003:
A Message From Earth 2008:

All other IRMs cannot be considered as serious METI-projects. Without going into details and excluding all futile and advertising cases of broadcasts into Space (for example, advertising of beer, chips or the new popular scientific book), we end up with only a couple of examples. In the “Deep Space Communications Network” service,, radio messages are transmitting with no definite address, low power, and without any special encoding that would allow decoding of these messages at the receiving side. The message “Across the Universe” [3] was sent to the Pole star, a supergiant whose surroundings are not suitable for any life; besides the message was compressed by “terrestrial” algorithms and transmitted with inappropriately high speed. The list of other futile radio messages can be found in [4], and a short history of the interstellar radio messages is presented in [5].

Summarizing, we would like to notice that there is a clear and undoubted distinction between serious METI-projects and idle METI profanations. This allows avoiding discredits of the METI idea, which recently have developed into a new social phenomenon.


1. Alexander Zaitsev. Messaging to Extra-Terrestrial Intelligence,
2. John Walker. Self-Decoding Messages,
3. “NASA Beams Beatles’ ‘Across the Universe’ Into Space”,
4. “List of Interstellar Radio Messages”,
5. Michael Marshall. Earth Calling: A Short History of Radio Messages to ET,


This article has been previously published at:

    • Rosaria & Antonio
    • July 1st, 2010

    Dear Alexander,
    is right, as you say, that to the basis of each message interstellar radio transmission there must be scientific and technological elements that must be addressed and resolved, as indicated by the basic issues of METI, by sending messages not by chance but by to stars with planets orbiting around them.
    Personally we do not agree with those who consider risky METI, wanting the end of the transmissions.
    Give up this would be like putting an end to that dream and to the question that always has fuelled the imagination of Humanity: we are alone in the universe?
    We realize, with the activity that we carry out, than this question, occupies and not only it has occupied the minds of great personalities of the culture, but also the simpler people, when they speak us about their experiences in the UFO field, if they placed in front of a possibility of a probable alien life in other worlds, many times and spontaneously, they have said – “In our opinion they are always existed” – as if this were for they a taken of conscience or contact with the deepest part of their human essence.
    Sure, communicating with alien civilizations – if there are – it is certainly not easy.
    From where to start when the language or culture it is not has in common?
    We don’t know what can reserve us the future in technological and scientific field, a lot of road there is to still do… new limits and new “Pillars of Hercules” by overcome.
    Therefore, Blaise Pascal we will not leave alone and frightened in front of the infinite silence of the Universe, that does really fear, because perhaps also “They” are to the search of a contact and however … is beautiful to think this!

    With best regards,
    Rosaria & Antonio

  1. Dear Rui,

    In addition to your comment:
    >It is my belief that, as we rapidly increase our
    >knowledge on exoplanets, these discoveries will
    >represent a turning point on the way we try to
    >communicate, or listen to, hypothetical alien
    >civilizations, and technology will be there to
    >help us on taking that amazing leap forward

    I would like to say that some my hopes on METI’s progress I repose on creative activity of Terrestrials, as it was stated in 2005 in “METI Art”:

  1. No trackbacks yet.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: