Radio Telescopes

Radio Telescopes

The great radio telescopes of the world are constructed in remote locations for the same reason Paul Gauguin sailed to Tahiti: For them to work well, they must be far from civilization. As civilian and military radio traffic has increased, radio telescopes have had to hide – sequestered in an obscure valley in Puerto Rico, say, or exiled to a vast scrub desert inn New Mexico or Kazakhstan.

As radio interference continues to grow, it makes increasing sense to build the telescopes off the Earth altogether. The scientists who work at these isolated observatories tend to be dogged and determined. Spouses abandon them, children leave home at the first opportunity, but the astronomers stick it out. Rarely do they think of themselves as dreamers. The permanent scientific staff in remote observatories tend to be the practical ones, the experimentalists, the experts who know a great deal about antenna design and data analysis, and much less about quasars or pulsars. Generally speaking, they had not longed for the stars in childhood; they had been too busy repairing the carburetor in the family car.

The word “quasar” is an acronym for “quasi-stellar radio source”. In the search for extraterrestrial intelligence, what could be done was so far ahead of what had been done (Carl Sagan and Megan Jorgensen). Image: © Elena

After receiving her doctorate, Ellie accepted an appointment as research associate at the Arecibo Observatory, a great bowl 305 meters across, fixed to the floor of a karst valley inn the foothills of northwestern Puerto Rico. With the largest radio telescope on Earth, she was eager to employ her maser detector to look at as many different astronomical objects as she could – nearby planets and stars, the center of the Galaxy, pulsars and quasars.

She also hoped to examine a few nearby stars for possible signals of intelligent origin. With her detector system it would be possible to hear the radio leakage from a planet like earth even if it was a few light-years away. And an advanced society, intending to communicate with us, would doubtless be capable of much greater power transmissions than we are.

If Arecibo, used as a radar telescope, was capable of transmitting one megawatt of power to a specific locale in space, then a civilisation only a little bit in advance of ours might, she thought, be capable of transmitting to the Earth with a telescope as large as Arecibo but with a hundred-megawatt transmitter, Arecibo should be able to detect them virtually anywhere in the Milky Way Galaxy.

When Ellie thought carefully about it, she was surprised that, in the search for extraterrestrial intelligence, what could be done was so far ahead of what had been done. The resources that had been devoted to this question were trifling, she thought. She was hard pressed to name a more important scientific problem.