SearchLites - Vol 04 No 2

Magazine Overview

SearchLites, Volume 4, Number 2, Spring 1998, is the quarterly newsletter of The SETI League, Inc. It is a membership-supported, nonprofit organization dedicated to the electromagnetic Search for Extra-Terrestrial Intelligence. The issue is 6 pages long and covers various topics related to SETI, amateur radio, and astronomy.

A Travel Report from our Executive Director

The Executive Director recounts a busy period of travel and engagement. In September 1997, he attended the first European Radio Astronomy Congress in Heppheim, Germany, hosted by Peter Wright, the SETI League coordinator for Germany. He expresses gratitude for the hospitality and regrets his limited time for sightseeing. In October, he was a banquet speaker at the Mid-Atlantic VHF Conference near Philadelphia and subsequently attended the AMSAT Space Symposium in Toronto and Microwave Update in Ohio. November involved meetings with SETI Institute colleagues near San Francisco, followed by a trip to Cambridge, MA, and Philcon in Philadelphia. December 1997 was quiet. In January 1998, he represented The SETI League at the International Conference on SETI in the 21st Century in Sydney, Australia, sponsored by the SETI Australia Centre. He enjoyed side trips to Brisbane and New Zealand, hosted by regional coordinators Noel Welstead and Wayne Thresher, where he addressed local clubs. The Director emphasizes that his technical conference presentations are posted online to establish credibility and that meeting local groups stimulates growth in Project Argus. He expresses encouragement from the enthusiasm of SETI League members and thanks his wife, Muriel Hykes, for her understanding of his prolonged absences.

SETI Advisor Knighted

Dr. Arthur C. Clarke, a distinguished author, futurist, and SETI League technical advisor, has been named a Knight Bachelor by Queen Elizabeth II. The article includes humorous instructions for visiting Americans on proper protocol when meeting royalty, with a specific exemption for SETI League members.

Ask Dr. SETI

This section addresses reader questions. The "Doctor" is identified as a Ph.D. who works for a living, not a medical doctor. Readers are encouraged to send questions to the provided PO Box or email address.

Dicke-switching

A reader from Norway asks about Dicke-switching for eliminating system noise. The Doctor explains that Dicke switches are primarily used to eliminate receiver gain fluctuations during measurements, not noise itself. The technique involves rapidly switching the receiver input between an antenna and a constant-temperature load resistor and measuring the difference in output. While not commonly used in amateur SETI, which relies on techniques like Fast Fourier Transform analysis, Dicke switches are popular in astrophysical observation. Radio Astronomy Supplies offers a Dickey switch kit.

The Drake Equation

Jan from Denmark questions the predictive power of the Drake Equation, viewing it as a matter of belief. The Doctor clarifies that the equation's importance lies in contemplation, not quantification. It was formulated as an agenda for the first SETI meeting in 1961 to summarize factors scientists consider when looking for extraterrestrial life. Initially, only stellar formation rate was well-estimated. Now, progress has been made in estimating extra-solar planets and habitable zones. The Doctor considers the Drake Equation a tool for quantifying ignorance.

Arecibo Message

RS from Switzerland inquires about a picture of a signal depicting human morphology, the solar system, and DNA. The Doctor confirms this refers to the Arecibo Interstellar Message transmitted on November 16, 1974, toward M13. The message, consisting of 1679 bits, graphically described a binary sequence, hydrocarbon chemistry, DNA, human morphology, the solar system, and the Arecibo dish. A detailed image can be found in Carl Sagan's 1980 book "Cosmos." The transmission was somewhat controversial due to concerns about transmitting from Earth.

Project ARGUS and the "Water Hole"

Monty G. from an unspecified location asks why the "Water Hole" frequency is associated with water and chosen for Project ARGUS. The Doctor explains that the "water hole" is a poetic description for the radiation lines of interstellar hydrogen and hydroxyl, which form water. These lines are in the quietest part of the microwave spectrum, visible from anywhere, and serve as signposts for civilizations. Since the region is already of interest for astrophysical phenomena and well-suited for interstellar propagation, it's a logical choice for SETI.

Identifying Intelligent Signals

Kirk from California is interested in objective standards for recognizing intelligent signals, specifically excluding noise filtering. The Doctor states that the current thinking is that narrow bandwidth is the hallmark of artificiality. Natural radiation spectra are hundreds of kiloHertz wide, whereas a stable signal occupying only a few Hz would be considered artificial. Doppler signatures viewed from multiple locations are used to eliminate terrestrial interference and hoaxes. The technique is discussed in an editorial on the SETI League's website. The Doctor also notes that SETI might stumble upon a narrow-band natural phenomenon, which would also be an exciting discovery.

Technical Feature: Testing the Operation of a SETI System by Using a Sun Traverse

By Ian Drummond, VE6IXD, a Project Argus Pioneer.

This article describes a method for testing the sensitivity of a SETI receiving system by measuring the change in power output when pointing towards and away from the sun. The method is based on articles by David Shaffer and Bob Atkins. The author used a 2.4 m dish, a helical feed, a Downeast Microwave SETI-LNA preamplifier, an ICOM R-7100 receiver, and a datalogger.

The procedure involved measuring the peak voltage (Vp) during the sun's traverse and the base voltage (Vb) when the dish was not pointed at the sun. The solar flux was obtained from WWV reports. Calculations were performed to determine the antenna temperature (Ta), receiver noise temperature (Trcvr), and the system's overall noise temperature (Tsun).

The author calculated Ta to be 750 K and Trcvr to be 140 K. He notes that the method used to position the feed horn might not have yielded the optimal signal-to-noise ratio. He also expresses a desire for a simpler way to calculate solar flux at SETI frequencies, as current methods rely on conversions to amateur bands.

Press Release: 100-Year-Old Hobby Takes On New Life

This press release from January 17, 1998, highlights how amateur radio, a century-old hobby, is being revitalized by its members applying their skills to SETI research. Dr. H. Paul Shuch, Executive Director of The SETI League, observes that as society matures, ham radio's role shifts towards skills like antenna design and signal analysis, essential for SETI. The SETI League aims to grow its global network to 5000 stations. The release mentions that since Congress terminated NASA's SETI funding in 1993, The SETI League and other groups are working to privatize the research. It provides contact information for those interested in participating or supporting the search.

Guest Editorial: ET Detection of Earth TV Unlikely

By Dale Lamm.

This editorial discusses the possibility of extraterrestrial intelligence (ETI) detecting Earth's television broadcasts. The author argues that while the idea has been discussed, it's unlikely that ETI would detect standard UHF TV signals from interstellar distances. The reasons cited include the high power required, the inefficiency of amplifiers, and the fact that TV broadcasters aim signals towards terrestrial receivers, not space. Energy radiated above the horizon is considered wasted, and side lobes are reduced in amplitude. The author suggests that military radars, such as SPASUR or other defense radars, might be better candidates for unintentional beacons. He also mentions Project Blackbeard, a satellite that observed Earth's TV and FM broadcasts from orbit. The author believes that ETI detection of Earth transmissions is still possible, perhaps through robot probes sent by long-lived civilizations, but not necessarily from interstellar distances via TV signals.

Recurring Themes and Editorial Stance

The SETI League, as presented in this newsletter, is actively engaged in promoting and facilitating the Search for Extra-Terrestrial Intelligence. The organization emphasizes the role of amateur radio operators and technical expertise in this endeavor. There is a clear stance on the importance of scientific rigor, even while acknowledging the speculative nature of SETI. The newsletter encourages participation, provides technical information, and addresses common questions and misconceptions about SETI. The editorial tone is informative, encouraging, and forward-looking, with a focus on privatizing SETI research and leveraging the skills of the amateur radio community. The magazine also highlights the international reach and collaborative nature of SETI efforts.