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During the week of August 16, an international group of scientists took up residence at the University of California in Santa Cruz to discuss progress in the search for life in the universe. Frank Drake, symposium organizer and Professor of Astronomy at the university, summarizes the topics covered at this very exciting meeting.
Bioastronomy — the study of the origin, nature and distribution of life in the universe — continues to provoke both interest and effort. Some of the hottest research topics in science, as well as some of mankind's most dramatic experiments, mark this field.
At the Santa Cruz meeting, more than 100 astronomers, biologists, chemists, sociologists, engineers, and educators from around the world came together to report progress in diverse disciplines all bearing on bioastronomy's common theme.
Most researchers believe that life will be pandemic only if Earth-like planets are also commonplace. Therefore, the search for planets beyond our Solar System is obviously relevant to any search for extraterrestrial life.
Attempts to directly photograph planets around other stars is still a seemingly hopeless task even for the world's largest telescopes, because a planet shines only about a billionth as brightly as its nearby stellar host. No doubt space telescopes of the future will be able to find planets in this straightforward way, but meanwhile astronomers are carefully measuring the very subtle motions of nearby stars to seek out the tell-tale dance that would betray encircling worlds. This is usually done with optical telescopes, but Very Long Baseline radio interferometry may work for stars that emit more than the usual amounts of radio energy. Another scheme discussed at Santa Cruz was to look for the very slight diminution in light from a star that is eclipsed by an orbiting planet.
While full-blown planets are hard to find, protoplanetary disks — planets in the making — are turning up everywhere. It seems that such disks last for ten million years, and then either turn into planets (good for SETI) or dissipate (bad for SETI), occasionally leaving a remnant disk. To decide which of these two scenarios is correct, researchers proposed looking for emission enhanced by maser and laser processes, and there is already some very encouraging observational evidence for these effects from Australian astronomers.
Most investigators are optimistic that planets will turn out to be plentiful, but what happens next? Is life easily cooked up, even on Earth-like worlds? In particular, our understanding of the early history of our own planet is in ferment. There is some evidence that temperatures on the archaic Earth might have been much warmer than at present, but how could this be? In particular, the aging process of stars would argue that the sun should have been 25% fainter in those distant days than it is now. The oceans should have been frozen solid.
One way around this conflict between expectation and evidence is to argue that the greenhouse effect may have been stronger during our planet's youth. Another possibility is that the Earth's pole was highly inclined. Yet another suggestion is that the Sun may have been about 5% larger at the time of Earth's formation, and therefore considerably brighter. The excess mass was slowly leaked away in the solar wind. We might find evidence of the same process occurring in other, very young Sun-like stars.
Keeping ancient oceans from freezing is a problem, but so is forming them in the first place. Participants at this conference noted the importance of comets in the story of life on Earth. Our planet's natal supply of volatile elements, which comprise the atmosphere and oceans, was most likely vaporized and dissipated by early impacts. Comets later replenished these constituents of life, and it may be that the giant planets (Jupiter, in particular) played a crucial role in scattering enough of these dirty ice balls into Earth's path. It seems that both our environment and our bodies are mostly comet stuff.
The incubation of life was the subject of several symposium presentations. Crystals exhibit a tantalizing ability to "reproduce," and conditions on the early Earth may have driven such inorganic processes in the direction of protein production. Chirality, or the "right" or "left-handedness" of life's molecules, is a persistent enigma in the story of life, and it may be that this asymmetry has an astrophysical cause; the polarized radiation from pulsars. Finally, an exciting result presented at the symposium was the tentative detection of glycine — the simplest amino acid, and a molecule occurring in all terrestrial life — in a cloud near the galactic center.
SETI is only one component of the bioastronomy matrix, but offers the promise of short-circuiting speculation on the processes of life by directly finding extraterrestrial cultures. Both the Planetary Society's project META, currently being conducted in Harvard, Massachusetts and in Argentina, and Berkeley's SERENDIP project [see article, this issue] have uncovered many dozens of interesting signals, although there is no good reason at present to believe that these are anything other than random noise or terrestrial interference. The NASA High Resolution Microwave Survey, begun last year, is increasing receiver capability as well as developing schemes for more efficient follow-up of any suspicious signals. It is interesting to note that since 1960, SETI detection capability has continued to double every 250 days.
Nearly all radio SETI searches are predicated on finding narrow-band continuous or slowly pulsing signals, but attendees at this symposium pointed out that the interstellar medium is an imperfect conduit for information. Signals will fade from one hour to the next, and any civilization interested in pumping large amounts of information across thousands of light-years will be constrained to use multiple radio carrier frequencies, due to scattering of their signal. Perhaps we should be looking for multi-frequency transmissions.
Other SETI approaches discussed at the symposium included searching for signals at optical wavelengths, building all-sky radio telescopes, or putting mammoth radio instruments into space. It was pointed out that such devices would be able to detect interstellar rockets, should other societies be using them.
While astronomy, biology and chemistry comprised the bulk of the symposium contributions, sociologists joined the fray by discussing what terrestrial reaction might be expected in the face of a SETI success, and even dared to tread into the area of alien psychology. Other participants looked for clues for the common characteristics of intelligence by studying diverse species on Earth.
Despite present-day financial constraints, bioastronomy activity is increasing greatly in many areas. Its effects extend beyond scientific research: The quest for life has also proven to be a powerful magnet to attract students to science.
When we engage in bioastronomy, we are asking questions about ourselves. How did we get here? Are we an inevitable product of the universe? What might we become? What can we achieve? And, finally, are we perhaps alone? For one week in the coastal town of Santa Cruz, a hundred of the world's scientists dared to consider how close we are to the answers.
Drake is Professor of Astronomy at the University of California, Santa Cruz and President of the SETI Institute, Mountain View, California.
It is frequently pointed out that SETI is only one component of the larger effort to study life in the cosmos.
Consequently, it is not surprising that about one-third of the papers presented at the Santa Cruz bioastronomy symposium held this August were in fields other than astronomy or space science. Many of these addressed the biological and chemical requirements for initiating life. Others dealt with the by now "traditional" problems of defining intelligence in other species or improving science education in our own. A few addressed sociological topics: Is space exploration an inevitable activity for advanced cultures? What would be the human reaction to the discovery of extraterrestrial intelligence?
In our lead article, Frank Drake, whose famous equation so succinctly describes the manifold disciplines of bioastronomy, reviews the high points of this one-week symposium. There were both new ideas, and ingenious attempts to deal with problems, such as the early temperatures on Earth or the fickle properties of the interstellar medium, whose importance is now more widely recognized.
If we step back and look at the big picture, one fact stands out: The picture is, indeed, big. Searching for life elsewhere is anything but a research niche. As the Santa Cruz symposium demonstrated, bioastronomy casts a wide net.
Shostak is Public Programs Scientist for the SETI InstituteResearchers at the University of California think they've found a clever alternative to traditional SETI approaches. They attach their equipment to a radio telescope that is already in use for conventional radio astronomy research, and just tag along for the ride. Such "piggyback" SETI requires no dedicated telescope use, and yet guarantees the Berkeley group virtually unlimited, low-cost time on the world's best telescopes.
The Berkeley project has the apt but imposing acronym SERENDIP: Search for Extraterrestrial Radio Emission from Nearby Developed Intelligent Populations. Right now, SERENDIP III is in place on the largest telescope in the world, the 304-meter dish at Arecibo Observatory in Puerto Rico. The folks at Arecibo have let SERENDIP run continuous piggyback observations on their 430 MHz receiver since April, 1992. In that time, SERENDIP has probed more of the generally recognized SETI "search space" than all other previous searches combined: 40 trillion radio channels at very high sensitivity, over one-third of the entire sky.
The next generation Berkeley machine is now under development. SERENDIP IV will be installed at Arecibo in about a year, and will employ a 167-million-channel spectrum analyzer.
Work by SERENDIP researchers has had a significant impact on the SETI community in general. The Berkeley team pioneered development of mechanisms to identify radio interference and to eliminate it from data streams. The SERENDIP II system was used by the NASA SETI project to survey interference at five different observatories.
Perhaps the greatest compliment for the SERENDIP design has come from other SETI researchers who want to adopt the system hardware. At Ohio State University, Robert Dixon is about to install a SERENDIP III system for dedicated use. Russian astronomers are also seeking a SERENDIP III system, but for now lack sufficient funding. Harvard's Paul Horowitz is adopting the SERENDIP IV architecture for the Planetary Society's next generation BETA machine.
SERENDIP is funded by NASA and by The Friends of SERENDIP, a small group of private donors headed by science writer Arthur C. Clarke. New supporters of SERENDIP can join the Friends by writing Professor Stuart Bowyer, Space Sciences Laboratory, University of California, Berkeley, California 94720.
Bowyer is a Professor of Astronomy and Werthimer is a Space Science Laboratory Engineer, both at UC Berkeley.
Have you ever been surprised by how well something works out? That's exactly what happened to us in Australia last year.
At the University of Western Sydney, Macarthur, all science degree candidates must follow at least one physics, one computing science, and one mathematics course during their studies. This is intended to familiarize students with the technological flavor of their future. Unfortunately, physics has never been a "favored" discipline in Australia, so we faced an uphill battle in our efforts to address the need for better science and technology education.
How could we improve the appeal and effectiveness of a physics course? We took a risk and created Physics 1.4, a survey course having maximum breadth and minimum mathematics. This would, we hoped, become the physics course that would appeal to students if nothing else did. Our hidden agenda was to improve the critical thinking and presentation skills of the students, regardless of their major.
We started with SETI and the Drake Equation. SETI offers a challenge to confront a wide range of science disciplines. It's also a subject upon which everyone has an opinion. But on what information were such opinions based?
The Drake Equation requires informed estimates of factors drawn from our current knowledge about the solar system, the Galaxy, the conditions under which life evolves, and so forth. So we reviewed these in the course. To assess SETI in the larger context of the universe, we needed to branch out into cosmology. But cosmology entails particle physics, relativity, and quantum mechanics. So those subjects were also included.
At this point, we were deep into human and environmental issues — the costs of nuclear energy, radioactive waste disposal, etc. We considered the costs, consequences and alternatives.
But of course in so doing, we couldn't ignore issues of human safety, the pressures of the international economy on societies, and the import of diverse philosophical and cultural contexts. "Real world" issues such as AIDS, the ozone hole and greenhouse effect, overpopulation, and the right to work — all of these were presented as troublesome, but unavoidable factors in the future world that our students would inhabit. Our rationale was that it is better to face the difficult issues than avoid them.
Did it work? The answer is a resounding "yes!" The students wanted more, and some even asked for more physics.
These students really worked hard in class, gave us a lot of useful feedback, and proved that innovation could make a positive difference in improving science education. The students loved it, and so did we.
Vaile heads the Department of Physics at the University of Western Sydney, Macarthur.
Is Anyone Out There? Frank Drake and Dava Sobel, Delacorte Press
(New York), 1992.
A fascinating personal history of the subject from the father of Project
Ozma.
We Are Not Alone. Walter Sullivan, E. P. Dutton (New York), 1993
[second edition].
An updated edition of a classic work.
The Search for Life in the Universe. Donald Goldsmith and Tobias
Owen, Addison-Wesley (Reading, Massachusetts), 1992 [second edition].
Another updated masterpiece.
Third Decennial US-USSR Conference on SETI. Seth Shostak (ed.),
Astronomical Society of the Pacific (San Francisco), 1993.
Three dozen papers by American and Soviet scientists.
Frontiers of Life. J.&K. Trân Thanh Vân, J.C.
Mounolou, J. Schneider, C. McKay (eds.), Editions Frontièrs (France),
1992.
Book of proceedings for the Third "Rencontres de Blois"
conference held at the Château de Blois in France, October 14-19, 1991.
Thank you very much for sending the SETI News. It is a very informative and important journal containing a lot of useful information. Please keep us on your mailing list. Is it possible to receive the back issues? And is there any subscription cost?
Hans-Ulrich Keller
Stuttgart, Germany
SETI News receives many letters inquiring about back issues and costs. There is no subscription fee for the newsletter, and recipients are never dropped from the mailing list unless we receive a request to that effect. Although we try to comply with requests for back issues, the supply is very limited, and for some issues, non-existent. — Ed.
Gathering issues from the SETI News, I find it disturbing that the red tape continues in order to avoid the real issues in the search for extraterrestrial intelligence... legitimate research of interstellar life forms. I have conducted field investigations in Arecibo and Los Alamos, New Mexico, but regardless of these findings, the issues of confirmation are still denied and avoided by NASA and SETI. I have spent a long weekend in El Yunque, Puerto Rico observing possible ufology discoveries, and...conclude that SETI is aware of these developments, monitors this communication, but fails to release this data in SETI News. Why?
Carlos del Campo
Miami, Florida
Judging from the points made in your letter, you apparently feel that NASA and possibly SETI News have evidence indicating that extraterrestrials have visited Earth (the UFO phenomenon). Clearly, if this were true it would be the biggest scientific discovery of all time. Alas, there isn't any irrefutable physical evidence for such visitors. Are there unexplained sightings? Yes, but unfortunately that doesn't prove very much. If a ship mysteriously sinks at sea, there are a multitude of possible explanations: mechanical failure, mutiny, bad weather, interference by extraterrestrials, etc. It would be unfair and illogical to single out the "extraterrestrial" explanation when the real cause cannot be determined.
Conspiracy theories are, by their nature, impossible to disprove. But until and unless physical evidence of visitation is put forth, it seems reasonable to conclude that our best hope for uncovering extraterrestrial intelligence is to pursue the detection of artificially produced signals. — Ed.
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