You know, while the evidence is compelling that UFOs are something unknown and unusual, the evidence that they are extraterrestrial craft isn't quite as compelling. So, some nights when I go out and look up at the sky, with all the multitude of stars spread across the blackness of space, I don't look for UFOs at all.
Instead, I let my mind drift out, feeling the immenseness of space tugging at me, and I wonder if we're alone after all. Sometimes, the answer that comes to my mind is that we are alone, that we are the result of a unique set of circumstances that has not occurred anywhere else in the universe and that may never occur again. But at other times, the thought comes to me that life must infest the universe as thoroughly it does the Earth. Sometimes it even seems that I can feel the presence of life out there calling to us, whispering in the dark.
Mankind has always felt this call, I think. Before we knew that there were other worlds out there, we attributed this call to the gods. Sometimes we tried to respond. The Nazca lines and figures may be an example. Maybe the Nazca Indians tried to signal the presence that they felt in the sky by duplicating the constellations they saw there in the dust of the Nazca Plains, reflecting them back at the heavens.
More recently, we have thought that there might be intelligent beings on nearby planets, and we tried to think of ways to signal them. In "Intelligence in the Universe" [Prentice-Hall, 1966], MacGowan and Ordway recall some of the schemes proposed for signaling other worlds:
One early experimenter who wanted to make a bold move to contact other worlds was Nikola Tesla, the brilliant, but eccentric, electrical pioneer. He set up equipment in his laboratory near Pikes Peak, Colorado in 1899 to "talk to the planets", as he expressed it. He sent powerful alternating surges of electricity into the ground, believing that the magnetic field of the Earth would increase the power of the signal. He made light bulbs glow miles away, but he was unable to detect any extraterrestrial response.
After the invention of radio, the emphasis shifted from that of trying to send a signal to that of trying to receive a signal from space. The hope was that other intelligences had radio too, and were trying to signal us.
David Peck Todd, Professor of Astronomy at Amherst College and friend of Percival Lowell, proposed operating a radio set from a dirigible 3000 meters above the ground for communicating with Martians in the belief they were capable of tuning in on our broadcast stations. Todd asked the U.S. Government to turn off its high-powered transmitters for five minutes before each hour to give him "silent periods" in which to listen for signals during the close transit with Mars from August 21 to August 23rd. The military responded by ordering all military stations to monitor and report any unusual signals, but didn't cutback normal transmissions. Professor Todd also requested that all radio stations maintain a five minute silence each hour over a two day period, but only WRC in Washington, DC cooperated. During these "silent periods" Todd used a receiver tuned to a wavelength between 5 and 6 kilometers to record any signals coming through. After sorting out the practical jokers, all he and listeners throughout the country could pick up was a potpourri of jumbled dots, dashes, and code groups, nothing that could be ascribed to an extraterrestrial source. We know today that such very long wavelengths as 5 or 6 kilometers are reflected back into space and could not have penetrated to the ground.
In August, 1924, the idea of communicating with Mars reached fever proportions because on August 23rd Mars and Earth would come to within 55.7 million kilometers of each other, their closest approach since 1804. No attempt was made to transmit signals to Mars because transmitters were still too weak, and the newly discovered ionosphere would absorb and scatter any signals sent from Earth on the frequencies then in use. Instead, it was hoped that the Martians had more powerful transmitters that would be able to bridge the gap. The task on Earth would be to try to intercept those transmissions.
|
The jumbled dots, dashes, and code groups that Todd did receive were recorded on photographic film, and in 1924 the New York newspapers for August of that year reported the following:
MYSTERY DOTS AND DASHES WAS MARS SIGNALLING? WHAT THE PHOTOGRAPHIC FILM REVEALED.
|
|
A giant step in the search for extraterrestrial intelligence came in 1932, when Karl Jansky, a radio engineer at the Bell Telephone Laboratories in New Jersey, built the first radio telescope. Another huge step was taken in 1937 when Grote Reber constructed a 10 meter parabolic dish antenna and began to make a radio map of the sky.
After World War II, the field of radio astronomy began to come into its own with the construction of ever larger radio telescopes. With this growth, some scientists began to speculate about the possibility of detecting intelligent signals from space. An article in the September 19, 1959, issue of Nature by Giuseppe Cocconi and Philip Morrison gave the idea some respectability. They recommended that a search for intelligent signals from beyond the solar system should be instituted with existing large radio telescopes in the microwave region around the 21 centimeter wavelength(1420 MHz), which is that of hydrogen. The idea caught the attention of a young radio astronomer named Frank D. Drake, and in 1960, when he was at the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia, he carried out humanity's first serious attempt to detect interstellar radio transmissions. He called it Project Ozma after the queen of L. Frank Baum's imaginary land of Oz -- a place "very far away, difficult to reach, and populated by strange and exotic beings." The stars he chose for the first SETI search were Tau Ceti in the Constellation Cetus the Whale and Epsilon Eridani in the Constellation Eridanus the River. Both stars are about eleven light years (66 trillion miles) away, are about the same age as our sun and seem reasonably likely to have inhabited planets. For six hours a day, from April to July 1960, the 85-foot Green Bank radio telescope was tuned to the 21-centimeter radio emission coming from hydrogen gas in interstellar space. The idea was that this frequency might be a kind of universal standard to anyone attempting interstellar radio communication. There's so much hydrogen in the universe that this frequency is a sort of marker in the radio spectrum. Drake's single 100 Hz channel receiver scanned 400 kHz of bandwidth. He and his associates scanned the tapes for a repeated series of uniformly patterned pulses that would indicate an intelligent message or a series of prime numbers such as 1, 2, 3, 5 or 7. Except for a false alarm caused by a secret military experiment, the only sound that came from the loudspeaker was static. But it was a milestone in that, after Project Ozma's first tentative steps, systematic searches for radio signals from intelligence on the planets of other stars became a scientifically feasible objective.
The Soviet Union dominated the search for extraterrestrial intelligence during the sixties, using a different strategy. Instead of searching only for signals from nearby stars, they scanned large chunks of sky using nearly-omnidirectional antennas. They were betting on the existence of at least a few highly advanced civilizations with extremely powerful transmitters. If they found anything, they didn't say. From 1973 to 1976, the U.S. got back into the act with Project Ozma II, also conducted at Green Bank by Benjamin Zuckerman and Patrick Palmer, who intermittently monitored more than 650 nearby stars. There were also other efforts that began in the 1970's, notably the Planetary Society's Project META, the University of California's SERENDIP project, and an observing program at Ohio State University's Big Ear radio telescope. In the late 1970's NASA began studying the problems involved in searching for extraterrestrial intelligence, and groups at the Ames Research Center and at the Jet Propulsion Laboratory (JPL) in Pasadena, California arrived at a two-pronged strategy for a large-scale SETI (Search for Extraterrestrial Intelligence) project. In 1988, after a decade of development, NASA funded the program and adopted a strategy whereby the Ames Center would examine 1,000 Sun-like stars in a Targeted Search, capable of detecting weak or sporadic signals, while the Jet Propulsion Laboratory would systematically sweep all directions in a Sky Survey. In 1992, on the 500th anniversary of Columbus' arrival in the New World, the listening began. However, the listening only lasted a year because a budget-conscious Congress terminated funding. Those who feel that call from the sky have not given up, however. NASA provided SETI with 15 million channels in 1992 using about 1/10 of 1% of its budget. Since then, the Planetary Society (formerly headed by Dr. Carl Sagan, author of Contact), the SETI League, and the SETI Institute have attempted to support the project with private funding. Project Phoenix is the privately funded continuation of the Targeted Search portion of NASA's terminated High Resolution Microwave Survey (HRMS). The Planetary Society has financed a dedicated search using the 84 foot radio dish at Harvard, Ma., an 8.4 million channel spectrometer and 400 kHz of bandwidth - Paul Horowitz's Project Meta II. Also continuing with private funding is the University of California's SERENDIP Project. The long-standing listening program using Ohio State University's Big Ear ended in 1997 and the Big Ear was torn down in early 1998. The SETI League is attempting to enlist amateur astronomers to perform an all sky survey in addition to targeted systems being surveyed by the Planetary Society. SETI continues in Australia as well.
Critics point out that years of listening have not produced any significant results and point to this overwhelming lack of results as a basis for discontinuing SETI. However, the search may provide benefits to society regardless of the results. Technological advancement is the most obvious contribution. The 8.4 million channel spectrometer that was developed for the Harvard project is an example of real technological advancement. Other projects continue. For the listeners, though, the motivation lies not in technological "fallout", but in answering the call, in the feeling that, as is said in the movie Contact, ... if it's just us, it seems like an awful waste of space. This article was previously published in 2000. It has been edited slightly.
|
