Alien Universe (32 page)

Drake long had an interest in searching the heavens for extraterrestrial radio signals. During some earlier astronomical research, he had picked up a transient signal that was never explained. While he was not prone to outlandish claims, the thought crossed his mind that perhaps the signal was not emitted from any transmitter on Earth. He tabled this idea while he pursued a more traditional research career. The quality of his research was what smoothed his way to a position at the newest and biggest radio facility around.

NRAO was a lively place, with groundbreaking in 1957 and construction on the 140 foot telescope beginning in 1958. A handful of physicists and buckets of money were tasked with building a breathtaking new radio astronomy laboratory. The big antenna was much bigger than earlier antennas, and its construction was plagued with more than the usual problems that come from building something never built before. Thus, in the meantime, NRAO decided to construct an 85 foot telescope, as this was much less of a technical challenge and would get the facility off and running. The 85 foot telescope started operations in early 1959.

It was the summer of 1959 before Drake could turn to his idea of using the NRAO facility to search for extraterrestrial signals. By consensus, the scientific staff agreed that (1) first priority had to go toward more traditional radio astronomy research and (2), given the potentially sensational nature of the extraterrestrial search, they should keep their efforts quiet. The idea was to do a simple search and to see what they could see without fear of interference that might accompany a negative newspaper story.

However, the world of high end scientific research was no less cutthroat in 1959 than it is today. There is a large degree to which it is true that in high stakes science, there is first and there is not-first. There is no second. In September 1959, a paper was published by two theoretically inclined physicists, Philip Morrison and Giuseppe Cocconi, which discussed how one might go about doing a radio search for extraterrestrials. Worried about losing credit for what was undoubtedly an important bit of research, Otto Struve, director of the Green Bank facility, announced the effort in a series of lectures given in November at Massachusetts Institute of Technology—just a mere two months after the theoretical paper came out. The lectures brought with them instant attention in the press. Articles in
Time
magazine, the
New York Times
, and the
Saturday Review
told the public that astronomers were going to try to listen for Alien broadcasts. The
Saturday Review
reported on Struve’s presentation: “He was struggling against going too far without falling too short of expressing what many astronomers have come to believe—that other intelligent beings
share our occupancy of the cosmos, that some of them are very probably superior to us, culturally, and that our existence is suspected by if not definitely known to them.”

The response in the press was typically positive. The exposure brought with it donations of cutting-edge amplifiers, which would enhance the performance of the equipment. The era of modern searches for extraterrestrial broadcasts had begun.

The term SETI (Searches for Extraterrestrial Intelligence) was not coined until the mid-1970s, but that is exactly what Drake and colleagues were doing. Drake named the 1960 effort “Ozma” after Princess Ozma in L. Frank Baum’s sequels to
The Wizard of Oz
. Baum claimed to be in radio contact with Oz, which is how he learned of his stories. Drake and company were attempting to contact a land far weirder than Baum’s fictional kingdom.

On April 8, 1960, Operation Ozma began operations. The team looked at two stars, Tau Ceti and Epsilon Eridani. Both were thought to be sufficiently like our sun to be interesting. Subsequent analysis has tempered somewhat the enthusiasm for these stars, but they remain targets for modern planet-hunting attempts. While observing these stars, there appeared to have been a transient signal from Epsilon Eridani, although this signal turned out to have a terrestrial origin. The study was a first try and therefore covered a limited amount of the radio spectrum. No extraterrestrial signal was observed.

This brings up an important point. The radio spectrum is quite broad and artificial broadcasts are quite narrow. The Federal Communications Commission has allocated the range from 9 kHz to 275 GHz for use. Translated to wavelength, these radio frequencies range from a fraction of an inch to a few miles in length. Although we shouldn’t expect extraterrestrials to comply with human choices, a single AM radio station can occupy about 20 kHz of that range, while an FM station can occupy 200 kHz. So, in the semi-arbitrary range used by humans, one can fit about 13 million AM stations and over a million FM ones. In order to see the technical details of a broadcast, the spectrum must be split even finer still. As we will see below, SETI searchers generally concentrate on a fraction of the possible radio spectrum, but still end up needing to simultaneously search hundreds of millions of radio channels.

While the radio spectrum is broad, the range of frequencies scientists use for SETI studies has historically been narrower. The particular range that is used has been selected to avoid frequency ranges that are noisy from naturally occurring sources. For instance, the Earth’s atmosphere radiates copiously for wavelengths below about an inch, while the galaxy radiates for wavelengths
above about a foot. Although these thresholds aren’t perfectly sharp, SETI scientists listening outside this wavelength range will have to contend with a much louder “radio hiss.” Further, we should remember that NRAO was really a radio astronomy facility and not a SETI one. This is not unusual and, even today, when a new facility is built, SETI is almost always a secondary consideration. Luckily the limitations imposed by unwanted radio noise affect radio astronomers and SETI researchers equally, allowing the same equipment to be used for both goals. NRAO was funded to study astronomical phenomena and so the equipment was optimized for a radio wavelength of about 8 inches, as this would allow researchers to study interstellar hydrogen to look for magnetic fields.

As we have seen, Ozma failed to observe any SETI signal, but it generated great excitement, culminating in the November 1961 conference at which the Drake equation was unveiled. A new era in exploratory science had begun.

In the intervening 50 years, there have been many SETI efforts, although there have certainly been gaps during which no observations were attempted. One telescope was built in Delaware, Ohio, and began operations in 1963. Funded by the National Science Foundation and operated by the Ohio State University, the facility was called Big Ear. From about 1963 to 1971, the facility was used for traditional radio astronomy research, mapping extrasolar radio sources. However, after NSF funding was cut, the facility turned to SETI research, operating from 1973 to 1995. In 1977, the so-called Wow! signal was reported, named for a prominent “Wow!” written on the printout where the signal was first observed (
figure 7.3
). It is still considered to be the most interesting extrasolar candidate radio transmission recorded so far (which doesn’t mean it was really extrasolar in origin). From the telescope’s orientation at the time, the signal appears to have originated in the constellation Sagittarius, near the Chi Sagittarii star group. Despite many additional attempts to observe this region of the sky, no similar signals have ever been observed.

As discussed above, in order to find radio transmissions over a very narrow wavelength range, it is important to be able to split up the radio spectrum very finely. The 1980s ushered in an era where it was possible to simultaneously study a million radio channels, followed by the billion-channel era of the 1990s. Because of these technical improvements, the rate of progress has increased rapidly, much like computer technology grows by leaps and bounds. Originally SETI searches were funded by the U.S. government, but they were always vulnerable to ridicule by budget-conscious politicians who could make some political hay by denigrating searches for “little green men.” In 1983, government funding was finally cut. SETI advocates persevered even without that source of money and in 1984, the SETI Institute began operations as a nonprofit, backed by private funding. First observations began in 1992.

FIGURE 7.3
.
The “Wow!” signal was recorded by a SETI researcher at the Big Ear radio astronomy facility.
The Ohio State University Radio Observatory and the North American AstroPhysical Observatory (NAAPO)
.

Current SETI searches are dominated by the Allen Telescope Array, named after Paul Allen, the project’s benefactor and cofounder of Microsoft. The technical effort was initially helmed as a collaborative effort between the SETI Institute and the University of California, Berkeley, although Berkeley has since pulled out and transferred the facility to SRI International. Even with Allen’s generous donations, the facility requires additional funding to successfully operate. Budgetary shortfalls forced the facility to go into mothballs in April 2011, although sufficient monies were procured to resume operations in December 2011. As of this writing, continuing operations remain in doubt. Given the inarguable consequences of a successful measurement of detection of a SETI signal, and the very modest needs, it seems to me that this is an unconscionable lapse in research priorities. The costs are small, and the potential payoff is incalculably huge.

So, what is the status of SETI searches in 2012? Well, so far, we haven’t found a radio signal originating from extraterrestrial intelligence or, if we have, we haven’t recognized it. We should also dispense with the conspiracy theories suggesting that the government is in contact with Aliens and just hasn’t told us. The big SETI efforts are civilian-run and further run by people with a lifelong passion for searching for our interstellar neighbors. In a world of blogs and leaks and rumors, I find it utterly inconceivable that a secret of
this magnitude could successfully be hidden. No ET signal is being covered up by the government.

But what do we know that we didn’t know 50 years ago? Well, the first thing we know is that there aren’t many radio-emitting civilizations similar to ours currently living in our local stellar community. The hopes of a universe filled with neighbors much like us have not proven to be true. As much as it makes me unspeakably sad, we don’t live in the
Star Trek
universe.

However, no matter how easy it is for SETI opponents to point at the failure after half a century of effort, SETI advocates can point at many possible explanations of why we’ve not yet succeeded. We have restricted the bulk of our studies to a limited range of radio space. Perhaps the Aliens have elected to broadcast in a different range. Perhaps the Alien’s signals haven’t reached us yet. Indeed, in the movie
Contact
, Aliens located near the star Vega first learned about Earth when the 1932 broadcast of the Olympics reached them. The Aliens recorded the broadcast and sent it back to us, amplified greatly. In their transmission, they interspersed their own message.

While we have no idea how we will one day encounter an extraterrestrial radio broadcast (if ever), under that plausible scenario, maybe the broadcast just hasn’t arrived yet. If Aliens living under the sun of Aldeberan (65 light-years away) received the 1932 broadcast and replied instantly, we wouldn’t hear their response until 2062. (Aldeberan, being a red giant, is an unlikely place to find an indigenous extraterrestrial civilization, although it is obviously possible that Aliens could have travelled there, so it could host a broadcasting antenna.)

While SETI advocates quite rightfully remind us that there are many perfectly reasonable reasons why we have not heard a radio broadcast by Aliens and we should continue looking, it is safe to say that the data taken thus far can rule out a nearby Kardashev level II or III civilization. It also seems equally safe to say that we probably don’t have a neighbor in our stellar neighborhood who has been broadcasting radio for hundreds of years. Nearby intelligent life, at least of the radio-broadcasting variety, seems to be rare. But the galaxy is big, and there is no reason to give up just yet.

Where Could Aliens Be?

If nearby intelligent and technologically advanced life is rare, why is that so? The Drake equation, for all its imperfections, tells us what parameters are the most important. We know that the universe makes stars and further we know it makes planets. As of this writing (spring 2012), NASA’s Kepler spacecraft
has observed 2,321 planets orbiting distant stars. In December 2011, NASA announced the first observation of a planet that circles a distant star in the “habitable zone,” which means that the planet could contain liquid water. That planet is called “Kepler-22b” and is the first of no doubt many such observations. By the time you read this, these numbers will be terribly out of date. Already, the Kepler team has announced another fifty candidates of potentially habitable extrasolar planets that need further study to be sure that they’re real.