SP-419 SETI: The Search for
Extraterrestrial Intelligence
[ii-iii] A portion of the
star field taken from the same photographic plate as shown on the
cover is reproduced on the right with the addition of designations of
stellar type for some of the stars. The letter designation (e.g., A)
indicates the spectral type of the star. The conventional spectral
types are 0, B, A, F, G, K, and M, with O-stars being the hottest
(effective surface temperatures in excess of 30,000 K) and M-stars
being the coolest (effective surface temperatures of 3,000 to 4,000
K; the effective surface temperature of the Sun is about 5,800 K).
The prefix ''g'' indicates that a star is a giant star, a star that
has moved away from the main sequence. Stars indicated only with the
spectral designation are main sequence stars, deriving their energy
primarily from the conversion of hydrogen into helium. The two
important aspects of the figure are first that stars like the Sun,
spectral type G, are very numerous in the Galaxy, and second, in any
typical group of stars, most stars are of spectral types G, K, and M.
These types of stars are long lived (10 billion years or greater).
The figure shows that viewed from the perspective afforded by
interstellar distances, the Sun would be a rather common and
ubiquitous type of object. This suggests that the Sun's retinue of
planetary companions, and perhaps the intelligent life forms existing
on one of these planets, may also be common and ubiquitous
phenomena.
[xi] TABLE OF
CONTENTS
- Foreword.
- Workshop
Members.
- Preface, Philip Morrison, Chairman.
-
- I. CONSENSUS.
- Introduction.
- The Impact of SETI.
- Conclusions.
- 1. It is both timely and feasible to
begin a serious search for extraterrestrial
intelligence.
- 2. A significant SETI program with
substantial potential secondary benefits can be undertaken
with only modest resources.
- 3. Large systems of great capability
can be built if needed.
- 4. SETI is intrinsically an
international endeavor in which the United States can take a
lead.
-
- II. COLLOQUIES.
-
- 1. Cosmic Evolution.
- Ichtiaque S. Rasool, Donald L. De
Vincenzi, and John Billingham
- 2. Cultural
Evolution.
- Mark A. Stull
- 3. Detection of Other Planetary
Systems.
- Jesse L. Greenstein and David C.
Black,
- 4. The Rationale for a Preferred
Frequency Band: The Water Hole.
- Bernard M. Oliver
- 5. Search Strategies.
- Charles L. Seeger
- 6. The Science of
SETI.
- David C. Black and Mark A. A
[xii] III. COMPLEMENTARY DOCUMENTS
-
- 1. Alternative Methods of
Communication.
- John H. Wolfe
- 2. Notes on Search
Space.
- Charles L. Seeger
- 3. Parametric Relations in a Whole
Sky Search.
- Bernard M. Oliver
- 4. Stellar Census.
- Charles L. Seeger
- 5. Summary of Possible Uses of an
Interstellar Search System for Radio Astronomy.
- Jeffrey N. Cuzzi and Samuel
Culkis
- 6. SETI Related Scientific and
Technological Advances.
- David C Black and Mark A. Stull
- 7. A Preliminary Parametric Analysis
of Search Systems.
- Roy Basler
- 8. Radio Frequency
Interference.
- Mark A. Stull and Charles L.
Seeger
- 9. Protection of a Preferred Radio
Frequency Band.
- Mark A. Stull
- 10. Responses to a Questionnaire
Sent to Leading Radio Observatories.
- Philip Morrison
- 11. The Soviet CETI
Report.
- 12. Searches to Date.
- 13. The Maintenance of
Archives.
- Charles L. Seeger
- 14. Selected Annotated
Bibliography.
- 15. Workshop Members, Biographical
Information, Workshop Meetings.
-
- [xiii] BRIEF TITLES FOR ILLUSTRATIONS
-
- Annotated Star
Field.
- View of Arecibo Observatory
in Puerto Rico.
- Frequency scan of a
[alpha]-Ophinchi.
- The Orion
Nebula.
- Arecibo search for
ETI in M33.
- Antennas at NASA
Mohave R & D site.
- Westerbork
synthesis map of M51.
- Concept of 300-m
space SETI system.
-
- BRIEF TITLES FOR FIGURES
-
- SECTION II-4
- Figure
1 - Free space microwave
window.
- Figure
2 - Terrestrial microwave
window.
- Figure
3 - Free space temperature
bandwidth index.
- Figure
4 - Terrestrial temperature
bandwidth index.
-
- SECTION II-5
- Figure
1 - Some frequency allocations
in the microwave window.
- Figure
2 - Major parameters of signal
detection.
-
- SECTION III-2
- Figure
1 - Pulsar signature.
-
- SECTION III-3
- Figure
1 - Off-axis signal detection
scheme.
- Figure
2 - System sensitivity
relations.
- Figure
3 - Antenna size
requirements.
-
- SECTION III-8
- Figure
1 - Bi-static radar range for
ISS receiver.
- Figure
2 - Peak side lobe levels of
radiation patterns for large antennae.
-
- [xiv] BRIEF TITLES FOR TABLES
-
- SECTION II-5
- Table
1 - High power terrestrial
radiations.
-
- SECTION III-1
- Table
1 - Mass ratios for two-way trip
to a[alpha]-Centauri.
-
- SECTION III-2
- Table
1 - Typical antenna
gains.
- Table
2 - Origin of system
noise.
- Table
3 - Powerful radars.
-
- SECTION III-3
- Table
1 - System parameters.
- Table
2 - Detection sensitivity and
cost.
-
- SECTION III-5
- Chart
1 - Capabilities of large SETI
systems.
-
[xv]
View of Arecibo Observatory in Puerto
Rico with its 300 m dish- the world's largest. A small fraction of
its observation time is devoted to ETI searches.
Cover and frontispiece kindly provided
by Prof. Jesse L. Greenstein, California Institute of Technology,
Hale Observatory, Pasadena, California.
