The Arecibo message to aliens was the first, and best known, interstellar broadcast. But it's far from being the only one.

On February 4, 2008, NASA cast off its sometimes stuffy image and employed its Deep Space Network of radio antennae – used to communicate with spaceprobes – to transmit the Beatles' song Across the Universe towards the Pole Star. Sir Paul McCartney was quoted as saying "Send my love to the aliens"; while John Lennon's widow Yoko Ono saw it as "the beginning of a new age in which we will communicate with billions of planets across the Universe."

But the focal point for interstellar relays has been the former Soviet Union's equivalent of the Deep Space Network, the huge radio telescope at Evpatoria in Ukraine (left). Russian radio astronomer Alexander Zaitsev switched on his extraterrestrial transmitter ten years ago. His "Cosmic Call" messages of 1999 and 2003 repeated the Arecibo message, with extra images and lessons that should help the aliens to understand what we're saying. Zaitsev sent the messages to nine nearby stars that have may have planets like the Earth.

Also, in 2001, Zaitsev transmitted the "Teen-Age Message" to six stars near the Sun. As it says on the can, a group of teenagers was involved in creating this message. They composed special music to get the aliens' feet (or tentacles) tapping, played on a Russian electronic synthesizer called the Theremin.

And now comes the invitation from Bebo...

Should we be worried about people extending the Earth’s social networks to space? England’s Astronomer Royal in the 1970s, Sir Martin Ryle, was certainly concerned about deliberate contact. He wrote to Frank Drake, after the Arecibo message was sent, saying it was "very hazardous to reveal our existence and location to the Galaxy; for all we know, any creatures out there might be malevolent - or hungry."

And anthropologist Jared Diamond points out that, on Earth, primitive societies have always been destroyed when they've come into contact with more advanced civilizations – as we’d expect space-faring aliens to be. "I'd create a society called SOOT – Switch Off Our Transmitters – to make sure that the most dangerous practice on Earth was stopped."

But it's already too late. Powerful TV signals have been blasting out from our planet for decades. If the aliens on planet Gliese 581c are tuning into our wavelengths, they've already seen the assassination of President Kennedy and the Moon-landings, and they’re about to witness the fall of the Berlin Wall.

If I'm in a cynical mood, I could suggest that our TV broadcasts will give the aliens a clearer message of what humans are about than the disingenuous messages from Bebo.

On the other hand, perhaps these personal messages will strike a chord in an alien's breast. Maybe the first flying saucer to land will carry a lovelorn lady extraterrestrial, seeking the guy who wrote: "Come and drop by Planet Earth someday, we would be happy to have you over, well ... I would anyway!"

For more information

The Bebo messages to Gliese 581c
http://apps.bebo.com/amfe/view

SETI researchers' reactions to messages from Earth
http://seedmagazine.com/news/2007/12/who_speaks_for_earth.php4

The Cosmic Call messages from Evpatoria
http://www.cplire.ru/html/ra&sr/irm/CosmicCall-2003/index.html