Page Content (OCR)
At 4 a.m. on | April, 1960, an experiment began in a lonely valley in West Virginia. The big 85-ft radio-telescope at Green Bank was trained on the star Tau-Ceti, 11.8 light years away. The young American astronomer, Dr Frank Drake, who enjoys considerable fame as a scientist and acted as leader of this project, wanted to tune in to the radio transmissions of other civilisations in order to pick up signals from unknown intelligences in outer space. The first series of experiments lasted 150 hours. They passed into history as project OZMA, although it was a failure. The experiment was broken off, not because some of the participating scientists expressed the view that there were no radio transmission in space, but rather because it was realised that at the time there was no apparatus sensitive enough to reach the desired goal. OZMA will not be the only experiment of its kind. Possibly a radio-telescope will be erected on the moon that will be able to scan the immeasurable spaces between the stars for radio signals, free from terrestrial interference. However, it must be asked whether the search for radio signals really helps our space research and whether it might not be more practical for us to do the sending of radio signals into space. Of course, we cannot expect unknown intelligences to understand Russian or Spanish or English and to be sitting There remain three possibilities by which we can make ourselves known: mathematical symbols, Laser beams and pictures. The first of these seems most likely to succeed. In order to send such symbols we shall have to discover and fix Intergalactic wavelengths that stand a good chance of being received throughout the cosmos. 1420 megahertz would provide such a frequency, for that is the radiation frequency of the neutral hydrogen that results from the collision of hydrogen atoms. Since hydrogen is an element, this radiation frequency could be known throughout the universe. Besides, 1420 megahertz lies outside the over-crowded scale of terrestrial wavelengths. The possibility of errors and interference factors would be reduced to a minimum. In this way radio impulses could be sent into space and if unknown intelligences exist they would recognise them. mirrors with them and set them up there. These mirrors—like the corner of a room— will consist of three reflecting planes standing at right angles to each other and will have the property of returning any light that strikes them back to the source of the light. ‘This mirror system will be bombarded from the earth by a Laser emitting flashes of light each lasting for a hundred millionth of a second. The Laser will be used in conjunction with a telescope with an aperture of 1-50 metres. The light reflected from the moon will be picked up by this telescope and led Chapter Eleven - The Search For Direct Communication there waiting to be contacted. In this connection a news item from Die Zeit for 22.12.67 is most interesting. Under the headline 'The moon will be bombarded by flashes' we read: 'The distance of the moon from the earth is known to the nearest few hundred yards, but astronomers refuse to be satisfied with that. So astronauts on one of the first flights to the earth's satellite will take to a photo-copier. 'The distance of the moon can then be determined to one and a half metres from the known speed of light and the time taken by a Laser beam for the journey there and back.'