SETI meets a social intelligence: Dolphins as a model for real-time interaction and communication with a sentient species

In the past SETI has focused on the reception and deciphering of radio signals from potential remote civilizations. It is conceivable that real-time contact and interaction with a social intelligence may occur in the future. A serious look at the development of relationship, and deciphering of communication signals within and between a non-terrestrial, non-primate sentient species is relevant. Since 1985 a resident community of free-ranging Atlantic spotted dolphins has been observed regularly in the Bahamas. Life history, relationships, regular interspecific interactions with bottlenose dolphins, and multi-modal underwater communication signals have been documented. Dolphins display social communication signals modified for water, their body types, and sensory systems. Like anthropologists, human researchers engage in benign observation in the water and interact with these dolphins to develop rapport and trust. Many individual dolphins have been known for over 20 years. Learning the culturally appropriate etiquette has been important in the relationship with this alien society. To engage humans in interaction the dolphins often initiate spontaneous displays, mimicry, imitation, and synchrony. These elements may be emergent/universal features of one intelligent species contacting another for the intention of initiating interaction. This should be a consideration for real-time contact and interaction for future SETI work.     

Frequency management and SETI: threats to SETI observations in the 1–3 GHz band

The nature of a SETI search makes observations uniquely vulnerable to radio frequency interference because the frequency of a possible ETI signal is unknown. Sensitive radio telescopes, sophisticated software and enhanced signal detection equipment are employed to detect faint signals in the 1–3 GHz frequency range. Frequency management at SETI occurs within a policy environment of the ITU spectrum allocation process. Increased demand by commercial satellite services for access to spectrum adjacent to bandwidth allocated to radio astronomy creates severe international and domestic pressures on SETI observations. Strategies for addressing the RFI problem at the international level will be discussed that include a contingency ITU allocation plan for exclusive use of a particular frequency range by SETI in the event a signal is detected. The lunar farside is, by international agreement, a radio quiet zone for use by radio astronomers. Protected from most human-generated emissions, a SETI radio telescope array on the lunar farside would provide reliable data with minimum interference.     

Analysis of a crossed Bragg cell acousto-optical spectrometer for SETI

The search for radio signals from extraterrestrial intelligent beings (SETI) requires the use of large instantaneous bandwidth (500 MHz) and high resolution (20 Hz) spectrometers. Digital systems with a high degree of modularity can be used to provide this capability, and this method has been widely discussed. Another technique for meeting the SETI requirement is to use a crossed Bragg cell spectrometer as described by Psaltis and Casasent. This technique makes use of the Folded Spectrum concept, introduced by Thomas. The Folded Spectrum is a 2-D Fourier Transform of a raster scanned 1-D signal. It is directly related to the long 1-D spectrum of the original signal and is ideally suited for optical signal processing. The folded spectrum technique has received little attention to date, primarily because early systems made use of photographic film which are unsuitable for the real time data analysis and voluminous data requirements of SETI. An analysis of the crossed Bragg cell spectrometer is presented as a method to achieve the spectral processing requirements for SETI. Systematic noise contributions unique to the Bragg cell system will be discussed.     

Project Phoenix and beyond. Pesek Lecture

Although there are no federally funded projects at this time, SETI (the search for extraterrestrial intelligence) is a vigorous exploratory science. There are currently eight observational programs on telescopes around the world, of which the Phoenix Project is the most comprehensive. Most of these projects are rooted in the conclusions of the pioneering studies of the early 1970's that are summarized in the Cyclops Report. Technology has experienced an exponential growth over the past two and a half decades. It is reasonable to reassess the Cyclops conclusions as SETI enters the next century. Listening for radio signals is still the preferred method of searching, however new technologies are making searches at other wavelengths possible and are modifying the ways in which the radio searches can and should be conducted. It may be economically feasible to undertake the construction of very large telescopes that can simultaneously provide multiple beams on the sky for use by SETI and the radioastronomy community.     

Short-pulse SETI

While most optical SETI experiments are configured to detect nanosecond pulses, the majority of their counterpart radio searches integrate for seconds to minutes, looking for unchanging narrow-band carriers or slowly pulsed modulation. The former approach is suggested as an effective way to stand out against stellar photon noise, while the latter approach is dictated by the dispersive effects of the interstellar medium as well as the high visibility of narrow-band signal components.In this paper, we consider effective signal strategies for those that produce, rather than simply search for, optical and radio beacons—signals that are designed to elicit responses from technological civilizations. By considering the communication problem from the point of view of the transmitters, rather than the receivers, we deduce some likely signal characteristics for beacons, and concommitant new strategies for SETI.     

Toward understanding the active SETI debate: Insights from risk communication and perception

Insights from the robust field of risk communication and perception have to date been almost totally absent from the policy debate regarding the relative risks and merits of Active SETI or Messaging to Extraterrestrial Intelligence (METI). For many years, the practice (or proposed practice) of Active SETI has generated a vigorous and sometimes heated policy debate within the scientific community. There have also been some negative reactions in the media toward the activities of those engaged in Active SETI. Risk communication is a scientific approach to communication regarding situations involving potentially sensitive or controversial situations in which there may be high public concern and low public trust. The discipline has found wide acceptance and utility in fields such as public health, industrial regulation and environmental protection. Insights from the scientific field of risk communication (such as omission bias, loss aversion, the availability heuristic, probability neglect, and the general human preference for voluntary over involuntary risks) may help those who have participated in either side of the debate over Active SETI to better understand why the debate has taken on this posture. Principles of risk communication and risk perception may also help those engaged in Active SETI to communicate more effectively with other scientists, the public, with the media, and with policy makers regarding their activities and to better understand and respond to concerns expressed regarding the activity.     

VLSI processors for signal detection in SETI

The objective of the Search for Extraterrestrial Intelligence (SETI) is to locate an artificially created signal coming from a distant star. This is done in two steps: (1) spectral analysis of an incoming radio frequency band, and (2) pattern detection for narrow-band signals. Both steps are computationally expensive and require the development of specially designed computer architectures. To reduce the size and cost of the SETI signal detection machine, two custom VLSI chips are under development. The first chip, the SETI DSP Engine, is used in the spectrum analyzer and is specially designed to compute Discrete Fourier Transforms (DFTs). It is a high-speed arithmetic processor that has two adders, one multiplier-accumulator, and three four-port memories. The second chip is a new type of Content-Addressable Memory. It is the heart of an associative processor that is used for pattern detection. Both chips incorporate many innovative circuits and architectural features.     

Limits on interstellar messages

Despite the fact that major efforts have been expended on passive searches for extraterrestrial signals, few deliberate “transmissions” to potential alien recipients have occurred. These have generally taken the form of simple graphics depicting such things as our appearance, location, and biological construction. In this paper, we consider (a) the fundamental technical and astronomical limitations to interstellar messaging—in other words, how many “bits” could any society reasonably send, and (b) what might be a likely transmission strategy. These considerations suggest approaches for SETI programs, as well as giving insight into the types of messages we might construct for eventual replies to received signals.     

The SERENDIP SETI project: new instrumentation for SETI and results of recent observations

Over the past 30 years research into the existence of extraterrestrial life has focused on attempts to detect stable narrowband radio signals emitted in the microwave portion of the radio frequency (RF) spectrum. The SERENDIP SETI group is currently conducting search operations on the world’s largest radio telescope at the Arecibo Observatory in Puerto Rico.The third generation SERENDIP system, SERENDIP III, is a 4 million channel FFT-based spectrum analyzer with 0.6 Hz frequency resolution. In this paper, we will discuss the results of our recent 3.5 year sky survey. SERENDIP looked at 95% of the sky visible from Arecibo in the 424–436 MHz range, analyzed 10¹⁴ spectral bins, and logged information on over 2.5×10⁸ signals.The fourth generation SERENDIP system expands on the SERENDIP III design. SERENDIP IV computes 2×10¹¹ operations each second, providing spectral analysis on 160 million channels in 1.7 s. We will discuss the design and use of the SERENDIP IV system and future observing plans.     

A symbiotic approach to SETI observations: use of maps from the Westerbork Synthesis Radio Telescope

High spatial resolution continuum radio maps produced by the Westerbork Synthesis Radio Telescope (WSRT) of The Netherlands at frequencies near the 21 cm HI line have been examined for anomalous sources of emmission coincident with the locations of nearby bright stars. From a total of 542 stellar positions investigated, no candidates for radio stars or ETI signals were discovered to formal limits on the minimum detectable signal ranging from 7.7 x 10(-22) W/m2 to 6.4 x 10(-24) W/m2. This preliminary study has verified that data collected by radio astronomers at large synthesis arrays can profitably be analysed for SETI signals (in a non-interfering manner) provided only that the data are available in the form of a more or less standard two dimensional map format.     

Positive consequences of SETI before detection

Even before a signal is detected, six positive consequences will result from the scientific search for extraterrestrial intelligence, usually called SETI. (1) Humanity’s self-image: SETI has enlarged our view of ourselves and enhanced our sense of meaning. Increasingly, we feel a kinship with the civilizations whose signals we are trying to detect. (2) A fresh perspective: SETI forces us to think about how extraterrestrials might perceive us. This gives us a fresh perspective on our society’s values, priorities, laws and foibles. (3) Questions: SETI is stimulating thought and discussion about several fundamental questions. (4) Education: some broad-gage educational programs have already been centered around SETI. (5) Tangible spin-offs: in addition to providing jobs for some people, SETI provides various spin-offs, such as search methods, computer software, data, and international scientific cooperation. (6) Future scenarios: SETI will increasingly stimulate us to think carefully about possible detection scenarios and their consequences, about our reply, and generally about the role of extraterrestrial communication in our long-term future. Such thinking leads, in turn, to fresh perspectives on the SETI enterprise itself.     

A novel SETI strategy targeting the solar focal regions of the most nearby stars

Many hypotheses have been raised to explain the famous Fermi paradox. One of them is that self-replicating probes could have explored the whole Galaxy, including our Solar System, and that they are still to be detected. In this scenario, it is proposed here that probes from neighboring stellar systems could use the stars they orbit as gravitational lenses to communicate efficiently with each other. Under this hypothesis, a novel SETI approach would be to monitor the solar focal regions of the most nearby stars to search for communication devices. The envisioned devices are probably not detectable by imagery or stellar occultation, but an intensive multi-spectral monitoring campaign could possibly detect some communication leakages. Another and more direct option would be to message the focal regions of nearby stars in an attempt to initiate a reaction.     

The first SETI observations with the Allen telescope array

The Search for ExtraTerrestrial Intelligence (SETI) finally has its own full-time telescope. The Allen telescope array (ATA) in Northern California was dedicated on October 11, 2007. This array, which will eventually be composed of 350 small radio antennas, each 6.1 m in diameter, is being built as a partnership between the SETI Institute and the University of California Radio Astronomy Laboratory. Last October, Paul G. Allen (who provided the funds for the technology development and the first phase of array construction) pushed a silver button and all 42 antennas of the current ATA-42 slewed to point in the direction of the distant galaxy M81. Specialized electronic backend detectors attached to the ATA began making a radio map of that galaxy and simultaneously began SETI observations of HIP48573, a G5V star near M81 on the sky and a distance of 264 light years from Earth. The Allen telescope array will greatly improve the speed of conducting SETI searches over the next few decades, and it will allow a suite of different search strategies to be undertaken. This paper summarizes some of the earliest SETI observations from the array, and describes the search strategies currently being planned.     

Invited Pesek lecture: Exploration rather than speculation–assembling the puzzle of potential life beyond Earth

Speculations about the existence of life beyond Earth are probably as old as mankind itself, but still there is no evidence – neither for its presence nor for its absence. Moreover, we neither know the necessary nor the sufficient conditions for life to emerge, sustain or evolve. The Drake equation famously quantifies our ignorance by writing the number of detectable civilizations as product of factors that get increasingly uncertain the further one goes to the right. As a result, the predictive power is poor, and it ultimately depends on the most uncertain factor. However, if we were able to derive a reasonable estimate, we would not need SETI experiments to tell us whether we are alone or not. What has changed substantially over human history is our ability to explore the Universe. Most significantly, radio transmission technology gives us the opportunity to communicate over interstellar distances, and we are now able to not only determine the population statistics of planets within the Milky Way, but even in principle to find biosignatures in their atmospheres. By finding life beyond Earth, we will learn how frequently it emerges. By finding signals from intelligent extra-terrestrial civilizations, we will get unprecedented insight into our biological, technological, and societal evolution. The Drake equation is not such a useful means for assessing the chances of success of SETI, but instead it provides the framework for using observational data in advancing towards understanding the origins of our existence and our role in the cosmos, and maybe to get a glimpse of our future.     

Space missions for SETI.

Radio Telescopes for SETI searches are less demanding than general purpose astronomical radio telescopes. This provides an opportunity to exploit economical approaches in designing SETI systems. Radio Telescopes in low Earth orbit offer no discernible advantages to SETI; indeed, they probably would perform more poorly than a telescope in any other location. Telescopes in geosynchronous orbits would be sufficiently far from Earth to mitigate greatly the deleterious effect of human radio transmissions. Telescopes on the far side of the moon would be superb both from a radio interference standpoint, and from a civil engineering standpoint. Single-reflector telescopes as large as 50 kilometers in diameter could be constructed with conventional materials. However, their costs appear prohibitive. The asteroid belt and the outer solar system are unpromising places to place a large radio telescope. Perhaps the ultimate radio telescope would utilize the sun as a gravitational lens, focusing radiation on free-flying 10-meter class or possibly larger radio telescopes located at distances of the order of 1000 A.U. from the sun. Such a combination has an energy collecting area at 10 centimeters wavelength equivalent to that of a radio telescope about 11 kilometers in diameter, or of the order of 3000 Arecibo radio telescopes. Such a system could detect transmitters with EIRP of the order of a gigawatt at a distance of the order of the distance to the galactic center.     

Search for high-proper motion objects with infrared excess

The possibility of interstellar migration has been theorized during the past thirty years in the form of “Dysonships” that, using non-relativistic propulsion systems, are able to colonize the Galaxy in a relatively short time compared to the age of the Galaxy and consequently penetrate inside our solar system too. Observational evidence of this can be potentially obtained using the present state of the art of telescopes and related sensors, by following aimed searches and an expanded SETI protocol. Some transient and unrepeated radio signals recorded during standard SETI observations might be due to the transit of high-proper motion artificial sources of extraterrestrial origin, which are expected to show a very weak optical emission, a strong infrared excess and occasional high-energy bursts in the X and Gamma-ray wavelength ranges. Such artificial sources might show an interest to Earth by sending probes to visit it: such a possibility can be investigated scientifically as well.     

基于Huffman最优二叉树支持向量机的舱音记录器背景信号识别

飞行器舱音记录器(CVR)记录的舱音信号,通常是语音声、警告声、开关按钮声和背景噪声等混合而成.目前国内对该类信号的分析和辨别主要是计算机译码后利用人耳进行辨听,存在不易准确分辨各种独立声音信号的缺点.针对舱音信号是一种非平稳性的时频信号,提出了基于多尺度最优小波包基的CVR背景信号特征提取算法,将10种典型信号进行小波包分解,以分解得到的子带能量作为信号初始特征,再根据类间最大距离准则选取最优小波包基,从而确定待识别信号最具有代表性的特征向量,最后基于Huffman最优二叉树支持向量机进行CVR背景信号分类.仿真实验结果表明,该方法的平均识别率为94.62%,可以应用于CVR背景声音信号的自动识别.     

SETI at the Nancay radiotelescope

The Nancay (France) radiotelescope has been used in June, 1981, to search for artificial monochromatic signals from 102 nearby stars, without success. A different approach to SETI is also considered based on the properties of wide band signals. A detection procedure, through Karhunen-Loeve analysis, is suggested.     

Recent progress on the lunar farside crater Saha proposal

The aim of this review, whose title might as well be “Toward a dedicated lunar farside radio observatory”, is to provide information for potential interested workers whom we invite to contribute to this multidisciplinary effort.First point: in view of the dramatic increase of radio interference due to the development of satellite-based human telecommunications, it will soon become impossible to conduct valuable high-sensitivity SETI observations from the terrestrial ground. It is why a few years ago I started an interdisciplinary and international endeavor to protect for the next 20/30 years a well specified lunar farside crater (Saha) which no Earth- or geostationary orbit-based radio emission could reach.After raising technical, programmatic, legal, astronautical, industrial, political, ethical issues at a number of conferences of international learned institutions, this enterprise is now of interest for the wider field of next generation high-sensitivity radioastronomy at large, from decametric to sub-millimetric waves.This last year, positive results were the creation of an IAA Sub-committee for “A Lunar SETI Study”, the presentation of a Resolution to the IAU for the protection of a potential lunar radio observatory site, discussions at the IAA/IISL Scientific-Legal Roundtable on SETI & Society at IAF Congress in Torino, the organization of a half-day Scientific Event at next COSPAR Assembly in Nagoya and the initiation of an IAA Cosmic Study on the subject.We shall conclude by outlining the next efforts to be initiated up to a real Moon radio observatory.