Subject: HRMS Update - January 1993 NASA HIGH RESOLUTION MICROWAVE SURVEY (HRMS) TARGETED

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Subject: HRMS Update - January 1993 NASA HIGH RESOLUTION MICROWAVE SURVEY (HRMS) TARGETED SEARCH AND SKY SURVEY STATUS INAUGURATION + 60 DAYS BACKGROUND The High Resolution Microwave Survey (HRMS) is part of the Toward Other Planetary Systems (TOPS) program in NASA's Solar System Exploration Division. The HRMS looks for evidence of planets orbiting other stars through radio emissions that may be produced by technological civilizations on any such planets. The HRMS has two search modes, a Sky Survey and a Targeted Search. The Sky Survey, managed by the Jet Propulsion Laboratory, uses 34-meter antennas in NASA's Deep Space Network to sweep the entire sky over a wide range of frequencies for the presence of strong signals. The Targeted Search uses the largest available radio telescopes to observe nearby sun-like stars over a narrower range of frequencies for weak signals. The Targeted Search is managed by NASA's Ames Research Center which is also the lead center for the HRMS. The combination of the two search modes is millions of times more comprehensive than the sum of all previous search programs. The observational phase of the HRMS was inaugurated at 1900 hours Universal Time on 12 October 1992, Columbus Day, at the NASA Goldstone Deep Space Communications Complex in California and the Arecibo Observatory in Puerto Rico. The Arecibo Observatory is part of the National Astronomy and Ionosphere Center, operated by Cornell University for the National Science Foundation. In a coordinated program, the Arecibo antenna pointed at the star GL615.1A and the Goldstone antenna began to scan a small area of sky that included the position of the target star. The beginning of the search generated world-wide interest in the media. This report presents an overview of the observations and results to date. INAUGURAL OBSERVATIONS Sky Survey Initial observations began with the new 34-meter antenna at the Venus Development Station at Goldstone. The project is using the available X-Band receiver which can be tuned from 8200 to 8600 MHz, and the Sky Survey Prototype System (SSPS). The SSPS divides 40 MHz of the spectrum into two million 20JHz channels and automatically looks for Continuous Wave signals as the search progresses. Each observation involves driving the antenna rapidly in a "sliding racetrack" pattern programmed to cover a "sky frame," a rectangular area of sky approximately 1 degree high and 30 degrees in length. While observing, the SSPS temporarily stores data from channels with power above a specified threshold level and excises data from channels affected by terrestrial signals. The scan pattern is designed so that each point in the frame will be scanned by the antenna at least twice (with slightly different offsets) at times separated by about 10 minutes. Candidate signals drawn from the temporary buffer are selected for verification tests at the completion of the sky frame. A total of 17 sky frames, including 4 repeat frames, have been observed at X-Band. To date, no candidates have passed the verification tests and the results are entirely consistent with the expected thermal noise statistics. Through January 1993, the SSPS will continue to observe about one day per week on the 34-meter antenna at Goldstone with an increase in allocated time later in the year. A special set of three sky frames covering parts of the galactic plane were observed repeatedly in the frequency bands 1600-1750 MHz and 1380-1430 MHz. These observations, using the available L-Band receiver on the 26-meter antenna at the Venus site, are designed to optimize radio astronomy data and improve interference excision algorithms. Targeted Search The Targeted Search System (TSS) used the 305-meter antenna of the Arecibo Observatory, the world's largest, for its initial observations. The TSS processed a 10 MHz bandwidth into more than 14 million channels simultaneously, producing parallel channel resolutions ranging from 1 Hz to 28 Hz. Data were analyzed in real-time for the presence of Continuous Wave (CW) and Pulsed signals that may drift in frequency by as much as 1 Hz per second. Observations focused on a list of 25 stars within 100 light years. Receivers provided by the observatory allowed observations in four frequency bands covering a total of about 300 MHz within the range from 1300 MHz to 2400 MHz. Each "observation" of a star in a particular frequency band consisted of three steps with the antenna first pointed at the star, then away from the star, and then back at the star. Each observing step lasted either 92 seconds or 299 seconds. Signals that were present only when the telescope was pointed at the star were considered potentially of extraterrestrial origin and were subjected to further tests. Signals that were present both "on" and "off" the star were deemed to be terrestrial interference signals. A total of 436 observations were conducted during the 200 hours of assigned telescope time. A large number of interference signals were detected and cataloged. Fifteen signals required further verification tests but all proved to be intermittent terrestrial signals. Since returning from Arecibo, the TSS is being reassembled in the TS development lab at NASA Ames. As expected, operational experience has indicated the need for modifications to several circuit boards and improvements to the control software. Over the next year the capability of the system will also be doubled to cover 20 MHz. This work is in preparation for observations of nearby sun-like stars in the Southern Hemisphere, scheduled to begin in 1994 at the 64-meter antenna of the Parkes Observatory in Australia. Parkes is part of the Australian Telescope National Facility operated by the Commonwealth Scientific Industrial Research Organization. Analysis of the data collected at Arecibo is now under way with the goal of developing better techniques for quickly identifying, classifying, and perhaps even avoiding interference signals. RESULTS No signals from beyond our Solar System have been detected yet. Although many signals have been detected, none appear to originate from a point on the sky as determined by our observation and verification strategies. Most of the signals were recognized immediately as terrestrial interference by the software. A few observations and sky frames detected signals that required verification tests. Nearly all verification tests have been performed at the site within minutes of the original detection. A few tests had to be performed on the following day. No signal passed this level of testing. The HRMS has successfully inaugurated its observational phase. Both the Targeted Search and the Sky Survey are using the lessons learned in the initial observations to improve the hardware, software, and observation techniques of the HRMS project. For more information, please contact: SETI Office NASA Ames Research Center M.S. 244-11 Moffett Field, CA 94035-1000 ##### ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Every once in a while, /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | try pushing your luck. |_____|/ |_|/ |_____|/ | ** End of article **

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