Search For Extraterrestrial Intelligence Project Research Articles

Developing a Drift Rate Distribution for Technosignature Searches of Exoplanets

A stable-frequency transmitter with relative radial acceleration to a receiver will show a change in received frequency over time, known as a “drift rate.” For a transmission from an exoplanet, we must account for multiple components of drift rate: the exoplanet’s orbit and rotation, the Earth’s orbit and rotation, and other contributions. Understanding the drift rate distribution produced by exoplanets relative to Earth, can (a) help us constrain the range of drift rates to check in a Search for Extraterrestrial Intelligence project to detect radio technosignatures, and (b) help us decide validity of signals-of-interest, as we can compare drifting signals with expected drift rates from the target star. In this paper, we modeled the drift rate distribution for ∼5300 confirmed exoplanets, using parameters from the NASA Exoplanet Archive (NEA). We find that confirmed exoplanets have drift rates such that 99% of them fall within the ±53 nHz range. This implies a distribution-informed maximum drift rate ∼4 times lower than previous work. To mitigate the observational biases inherent in the NEA, we also simulated an exoplanet population built to reduce these biases. The results suggest that, for a Kepler-like target star without known exoplanets, ±0.44 nHz would be sufficient to account for 99% of signals. This reduction in recommended maximum drift rate is partially due to inclination effects and bias toward short orbital periods in the NEA. These narrowed drift rate maxima will increase the efficiency of searches and save significant computational effort in future radio technosignature searches.

Analysis of the Breakthrough Listen signal of interest blc1 with a technosignature verification framework

The aim of the search for extraterrestrial intelligence (SETI) is to find technologically capable life beyond Earth through their technosignatures. On 2019 April 29, the Breakthrough Listen SETI project observed Proxima Centauri with the Parkes ‘Murriyang’ radio telescope. These data contained a narrowband signal with characteristics broadly consistent with a technosignature near 982 MHz (‘blc1’). Here we present a procedure for the analysis of potential technosignatures, in the context of the ubiquity of human-generated radio interference, which we apply to blc1. Using this procedure, we find that blc1 is not an extraterrestrial technosignature, but rather an electronically drifting intermodulation product of local, time-varying interferers aligned with the observing cadence. We find dozens of instances of radio interference with similar morphologies to blc1 at frequencies harmonically related to common clock oscillators. These complex intermodulation products highlight the necessity for detailed follow-up of any signal of interest using a procedure such as the one outlined in this work.

Breakthrough Listen is scanning more of space than ever to try to find intelligent life

IN 1960, ASTRONOMER FRANK DRAKE turned the radio telescope at the National Radio Astronomy Observatory in Green Bank, W.Va., toward two nearby sunlike stars to search for transmissions from intelligent extraterrestrial societies. With a pair of headphones, Drake listened to Tau Ceti and Epsilon Eridani for a total of 150 hours across multiple sessions. He heard nothing, except for a single false positive that turned out to be an airplane. · Statistically speaking, Drake's pioneering project had little chance of success. Estimates from both NASA and the European Space Agency (ESA) suggest that our galaxy alone contains roughly 100 billion stars. (And there are perhaps 2 trillion galaxies in the universe.) · Nevertheless, Drake's effort, called Project Ozma, launched the modern search for extraterrestrial intelligence (SETI) efforts that continue to this day. But given the universe's size, a SETI project trying to make even the smallest dent in searching for intriguing signals needs to be much more than one astronomer with a pair of headphones. The project will need more telescopes, more data, and more computational power to find such signals. Breakthrough Listen has all three.

Choosing a Maximum Drift Rate in a SETI Search: Astrophysical Considerations

Abstract A radio transmitter that is accelerating with a non-zero radial component with respect to a receiver will produce a signal that appears to change its frequency over time. This effect, commonly produced in astrophysical situations where orbital and rotational motions are ubiquitous, is called a drift rate. In radio SETI (Search for Extraterrestrial Intelligence) research, it is unknown a priori which frequency a signal is being sent at, or even if there will be any drift rate at all besides motions within the solar system. Therefore drift rates across the potential range need to be individually searched and a maximum drift rate needs to be chosen. The middle of this range is zero, indicating no acceleration, but the absolute value for the limits remains unconstrained. A balance must be struck between computational time and the possibility of excluding a signal from an ETI. In this work, we examine physical considerations that constrain a maximum drift rate and highlight the importance of this problem in any narrowband SETI search. We determine that a normalized drift rate of 200 nHz (e.g., 200 Hz s−1 at 1 GHz) is a generous, physically motivated guideline for the maximum drift rate that should be applied to future narrowband SETI projects if computational capabilities permit.

Invasion percolation solves Fermi Paradox but challenges SETI projects

AbstractNon-homogeneous fractal-like colonization processes, where the cluster of visited sites has large voids and grows slowly, could explain the negative results of Search for Extraterrestrial Intelligence (SETI) preserving the possibility of a galactic spanning civilization. Here we present a generalized invasion percolation model to illustrate a minimal colonization process with large voids and delayed colonization. Spatial correlation between unvisited sites, in the form of large empty regions, suggests that to search civilizations in the Sun neighbourhood may be a misdirected SETI strategy. A weaker form of the Fermi Paradox also suggests this last conclusion.

Extraterrestrial contact: Creating xenolinguistic sonic messages for extraterrestrial communication – Ether Ship electronic music orchestrations in the Anza-Borrego Desert

Abstract Communication with other life forms in our universe has been an ongoing effort most notably conducted by the Search for Extraterrestrial Intelligence Project (SETI). Whereas SETI uses a network of radio telescopes to search for frequencies that may indicate intelligent design, there are also attempts to communicate with extraterrestrials by using different ways to listen for messages as well as send messages. This article outlines a phenomenological approach that includes changes in cognition due to the creation of electronic sounds mixed with stellar acoustics, radio frequencies, and natural and manmade sounds as a way of experiencing changes in cognitive states. These cognitive states may be related to a conscious contact with other life forms not from our world. In this sense it is a galactic approach to interspecies communication.

Fermi's paradox: The last challenge for copernicanism?

We review Fermi's paradox (or the 'Great Silence' problem), not only arguably the oldest and crucial problem for the Search for ExtraTerrestrial Intelligence (SETI), but also a conundrum of profound scientific, philosophical and cultural importance. By a simple analysis of observation selection effects, the correct resolution of Fermi's paradox is certain to tell us something about the future of humanity. Already more than three quarters of century old puzzle and a quarter of century since the last major review paper in the field by G. David Brin has generated many ingenious discussions and hypotheses. We analyze the often tacit methodological assumptions built in various answers to this puzzle and attempt a new classification of the numerous solutions proposed in an already huge literature on the subject. Finally, we consider the ramifications of various classes of hypotheses for the practical SETI projects. Somewhat paradoxically, it seems that the class of (neo)catastrophic hypotheses gives, on the balance, the strongest justification to optimism regarding our current and near-future SETI efforts.

Is the "Star trek" concept of aliens really naive?: A comment on Duric and Field

Several assumptions used in the recent review paper on the search for extraterrestrial intelligence (SETI) by Duric and Field (2003) are critically discussed. New astrobiological results-in particular those on the age distribution of terrestrial planets-enable relaxing of some of these assumptions, which gives further justification to optimism regarding SETI projects.

The Search for Extraterrestrial Intelligence (SETI)

▪ Abstract The search for evidence of extraterrestrial intelligence is placed in the broader astronomical context of the search for extrasolar planets and biomarkers of primitive life elsewhere in the universe. A decision tree of possible search strategies is presented as well as a brief history of the search for extraterrestrial intelligence (SETI) projects since 1960. The characteristics of 14 SETI projects currently operating on telescopes are discussed and compared using one of many possible figures of merit. Plans for SETI searches in the immediate and more distant future are outlined. Plans for success, the significance of null results, and some opinions on deliberate transmission of signals (as well as listening) are also included. SETI results to date are negative, but in reality, not much searching has yet been done.

A new approach to anticancer drug discovery

Distributed, or peer-to-peer, processing is an ingenious way of tackling really big analyses, by parcelling out small amounts of data to thousands of participating computers around the world. These data are analysed using software that runs as a screensaver, and takes up only a fraction of the spare capacity that every PC has. The idea is not a new one. Since its launch in 1999, the SETI (Search for Extraterrestrial Intelligence) project has recruited nearly 3 million computers to analyse radiowaves from outer space in a search for extraterrestrial messages. Now, however, a problem that is much closer to home is being tackled in the same way, as thousands of PCs are linking up to analyse computer-generated molecules in the hope of identifying possible new anticancer drugs.

The MCSA 2.1: A fully digital real-time spectrum analyzer developed for NASA's SETI Project

The MCSA 2.1, the Multi-Channel Spectrum Analyzer, is a fully digital spectrometer optimized for the detection of narrow-band signals. The MCSA 2.1 has a single analog input, which is fed to an analog-to-digital (A/D) converter running at 130 M samples per second, and hence covers a 65 MHz bandwidth. The MCSA 2.1 design includes a digital downconverter, which bandpasses 10 MHz, downshifts it to baseband, and outputs complex samples at 10.833 MHz. This 10 MHz “superband” is split into 144 “bands” of 69.4 kHz, then further split into 108 “subbands” of 643 Hz, then divided into “bins” of six simultaneous resolutions: 1, 2, 4, 7, 14, and 28 Hz. The data from each resolution is normalized by the estimated noise power and then output as: (1) 4-bit power for incoherent Continuous Wave (CW) detection; (2) 8-bit thresholded power for pulsed signal detection; and (3) 32-bit complex amplitude for almost non-drifting coherent CW detection and for possible future signal detectors. The MCSA 2.2 has two inputs, exactly twice the hardware, and processes two antenna polarizations which are available at radioastronomy observatories. The MSCA 2.2 includes 70 Printed Circuit Boards (PCB), including 10 custom logic board designs and two buffer board designs. The system is under development for NASA's Search for Extra-Terrestrial Intelligence (SETI) Project. Provided adequate NASA funding is available, the MCSA 2.2 will be installed and performing SETI searches in October 1992.

A self-organizing pattern retrieval system and its applications

This article is an overview of research on the design and application of a Self-Organizing Pattern Retrieval System. This system is a nontraditional form of database for several reasons: (1) the objects (patterns) stored in the database are complex data structures such as graphs, or matrices as opposed to relations, sets, lists or frames; (2) the system attempts to optimize its internal structure for retrieval efficiency by taking advantage of classificatory information (common patterns) it discovers about the patterns in the database; and (3) the system is representation-independent, allowing the user to use whatever representation scheme he desires as long as he provides a small set of I/O routines and comparison functions for the representation. This system has been applied to the organization of molecules and reactions in organic chemistry. the system is able to select valid precursors to molecules based on its knowledge of real-world reactions. It is also able to suggest new chemical reactions based on generalizations from its knowledge base. the system has also been applied to the retrieval, generalization, and classification of chess positions. Its ability to recognize the tactical similarity of positions is compared with that of a chess master. the design objectives of a system for classifying Radio Frequency Interference required by NASA's SETI (Search for ExtraTerrestrial Intelligence) project is also discussed.

Spectral-line sky surveys from the NASA-JPL SETI project

The Jet Propulsion Laboratory (California Institute of Technology) has recently begun preparations for a modest SETI (Search for Extra-Terrestrial Intelligence) project at radio wavelengths. The proposed project is two-fold: (1) to search the entire sky visible from Goldstone, California (site of one of the NASA Deep Space Network Stations), i.e. that north of δ ∼ −30°, at all frequencies between 1 and 24 GHz using a horn receiver and (2) to carry out a more sensitive sky search at a few selected frequency bands, using dedicated 26 and 10m antennas. The search will be for signals of the type unlikely to be produced by natural causes, e.g. narrow spikes in frequency space. The basic rationale behind this search is discussed by Murray, Gulkis and Edelson (1978).