Skip to main content Accessibility help
Hostname: page-component-cf9d5c678-r9vz2 Total loading time: 0.226 Render date: 2021-08-04T01:07:13.501Z Has data issue: true Feature Flags: { "shouldUseShareProductTool": true, "shouldUseHypothesis": true, "isUnsiloEnabled": true, "metricsAbstractViews": false, "figures": true, "newCiteModal": false, "newCitedByModal": true, "newEcommerce": true, "newUsageEvents": true }

Intermittent signals and planetary days in SETI

Published online by Cambridge University Press:  01 April 2020

Robert H. Gray
Gray Consulting, 3071 Palmer Square, Chicago, IL60647, USA


Interstellar signals might be intermittent for many reasons, such as targeted sequential transmissions, isotropic broadcasts that are not 'on' continuously or many other reasons. The time interval between such signals would be important, because searchers would need to observe for long enough to achieve an initial detection and possibly determine a period. This article suggests that: (1) the power requirements of interstellar transmissions could be reduced by orders of magnitude by strategies that would result in intermittent signals, (2) planetary rotation might constrain some transmissions to be intermittent and in some cases to have the period of the source planet, and (3) signals constrained by planetary rotation might often have a cadence in the range of 10–25 h, if the majority of planets in our Solar system are taken as a guide. Extended observations might be needed to detect intermittent signals and are rarely used in SETI but are feasible, and seem appropriate when observing large concentrations of stars or following up on good candidate signals.

Research Article
Copyright © The Author(s) 2020. Published by Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)


Backus, PRand Project Phoenix Team (2004) Project phoenix: a summary of SETI observations and results 1995–2004, American Astronomical Society Meeting 204 #75.04. Bulletin of the American Astronomical Society 36, 805.Google Scholar
Benford, G, Benford, J and Benford, D (2010) Searching for cost-optimized interstellar beacons. Astrobiology 10, 491498.CrossRefGoogle ScholarPubMed
Campbell, DB, Hudson, RS and Margot, J-L (2002) Advances in planetary radar astronomy. In Stone WR (ed.), Review of Radio Science 1999–2002. John Wiley & Sons, pp. 869899. Available at Scholar
Castellano, T, Doyle, L and McIntosh, D (2004) Visibility of Earth transits. In Penny, A, Artymowicz, P, Lagrange, A and Russell, S (eds), Planetary Systems in the Universe – Observation, Formation and Evolution, IAU Symposium No. 202, Astronomical Society of the Pacific, San Francisco, pp. 445–447.Google Scholar
Chatterjee, S, Law, CJ, Wharton, RS, Burke-Spolaor, S, Hessels, JWT, Bower, GC, Cordes, JM, Tendulkar, SP, Bassa, CG, Demorest, P, Butler, BJ, Seymour, A, Scholz, P, Abruzzo, MW, Bogdanov, S, Kaspi, VM, Keimpema, A, Lazio, TJW, Marcote, B, McLaughlin, MA, Paragi, Z, Ransom, SM, Rupen, M, Spitler, LG and van Langevelde, HJ (2017) The direct localization of a fast radio burst and its host. Nature 541, 5861.CrossRefGoogle ScholarPubMed
Chennamangalam, J, MacMahon, D, Cobb, J, Karastergiou, A and Siemion, APV (2017) SETIBURST: a robotic, commensal, realtime multi-science backend for the Arecibo telescope. Astrophysical Journal Supplement Series 228, 2129.CrossRefGoogle Scholar
Coddington, O, Lean, JL, Pilewskie, P, Snow, M and Lindholm, D (2016) A solar irradiance climate data record. Bulletin of the American Meteorological Society 97, 12651282.CrossRefGoogle Scholar
Colomb, FR, Hurrell, E, Lemarchand, GA and Olald, JC (1995) Results of two years of SETI observations with META II. In Shostak, GS (ed.), Progress in the Search for Extraterrestrial Life, vol. 74, ASP Conf. Series, Astronomical Society of the Pacific, San Francisco, pp. 345352.Google Scholar
Corbet, RH (2003) Synchronized SETI – the case for ‘Opposition’. Astrobiology 3, 305315.CrossRefGoogle Scholar
Cordes, JM and Lazio, TJW (1991) Interstellar scattering effects on the detection of narrow-band signals. Astrophysical Journal 376, 123.CrossRefGoogle Scholar
Cordes, JM, Lazio, TJW and Sagan, C (1997) Scintillation-induced Intermittency in SETI. Astrophysical Journal 487, 782.CrossRefGoogle Scholar
Correia, ACM and Laskar, J (2003) Long term evolution of the spin of Venus – II. Numerical simulations. Icarus 163, 24.CrossRefGoogle Scholar
Cullers, K (2000) Project phoenix and beyond. In Lemarchand, G and Meech, K (eds), Bioastronomy '99: A New Era in Bioastronomy, vol. 213, ASP Conf. Series, Astronomical Society of the Pacific, San Francisco, pp. 345–352.Google Scholar
Dixon, RS (1973) A search strategy for finding extraterrestrial radio beacons. Icarus 20, 187.CrossRefGoogle Scholar
Dixon, RS (1985) The Ohio SETI program – the first decade. In Papagiannis, MD (ed.), The Search for Extraterrestrial Life: Recent Developments, IAU Symposium 112. Dordrecht: D. Reidel Publishing, pp. 305314.CrossRefGoogle Scholar
Dodson, R, Lewis, D and McCulloch, P (2007) Two decades of pulsar timing of Vela. Astrophysics and Space Science 308, 585.CrossRefGoogle Scholar
Drake, F (1980) N is neither very large nor very small. In Papagiannis, MD (ed.), Strategies for the Search for Life in the Universe. Dordrecht: D. Reidel Publishing, pp. 2734.CrossRefGoogle Scholar
Drake, F (1985) Project Ozma. In Kellermann, KI and Seielstad, GA (eds), The Search for Extraterrestrial Intelligence, Proceedings of the NRAO Workshop, Green Bank: National Radio Astronomy Observatory, pp. 1726.Google Scholar
Drake, F, Wolfe, JH and Seeger, CL (eds) (1984) SETI Science Working Group Report, NASA TP-2244, Ames Research Center, Moffett Field, CA, p. 5.Google Scholar
Ekers, RD, Cullers, KC, Billingham, J and Scheffer, LK (eds) (2002) SETI 2020: A Roadmap for the Search for Extraterrestrial Intelligence. Mountain View, CA: SETI Press.Google Scholar
Ellingson, SW, Hampson, GA and Childers, RK (2008) Argus: an L-band all-sky astronomical surveillance system. IEEE Transactions on Antennas and Propagation 56, 294.CrossRefGoogle Scholar
Enriquez, JE, Siemion, A, Foster, G, Gajja, V, Hellbourg, G, Hickish, J, Isaacson, H, Price, DC, Croft, S, DeBoer, D, Lebofsky, M, MacMahon, D and Werthimer, D (2018) The breakthrough listen search for intelligent life: 1.1–1.9 GHz observations of 692 nearby stars. Astrophysical Journal 849, 104. Available at Scholar
Garrett, M, Siemion, A and van Cappellen, W (2017) All-Sky SETI, presentation at MeerKAT Science: on the pathway to the SKA, 25–27 May, 2016, Stellenbosch, South Africa. Available at Scholar
Gray, RH (1994) A search of the wow locale for intermittent radio signals. Icarus 112, 485.CrossRefGoogle Scholar
Gray, RH and Ellingsen, S (2002) A search for periodic emissions at the wow locale. Astrophysical Journal 578, 967. Available at Scholar
Gray, RH and Marvel, KB (2001) A VLA search for the Ohio State Wow. Astrophysical Journal 546, 1171. Available at Scholar
Gray, RH and Mooley, K (2017) A VLA search for radio signals from M31 and M33. Astronomical Journal 153, 110. Available at Scholar
Han, E, Wang, SX, Wright, JT, Feng, YK, Zhao, M, Fakhouri, O, Brown, JI and Hancock, C (2014) Exoplanet orbit database. II. Updates to Publications of the Astronomical Society of the Pacific 126, 827.CrossRefGoogle Scholar
Harp, GR, Richards, J, Tarter, J, Dreher, J, Jordan, J, Shostak, S, Smolek, K, Kilsdonk, T, Wilcox, BR, Wimberly, MKR, Ross, J, Barcott, WC, Ackermann, RF and Blair, S (2016) SETI observations of exoplanets with the Allen telescope array. Astronomical Journal 152, 181.CrossRefGoogle Scholar
Harp, GR, Gray, RH, Richards, J, Tarter, J and Shostak, S (2019) An ATA search for a repetition of the wow signal, AJ submitted.Google Scholar
Heller, R and Pudritz, RE (2016) The search for extraterrestrial intelligence in Earth's solar transit zone. Astrobiology 16, 259.CrossRefGoogle ScholarPubMed
Horowitz, P and Sagan, C (1993) Five years of project META: an all-sky narrow-band radio search for extraterrestrial signals. Astrophysical Journal 415, 218.CrossRefGoogle Scholar
Howard, AW, Horowitz, P, Wilkinson, DT, Coldwell, CM, Groth, EJ, Jarosik, N, Latham, DW, Stefanik, RP, Willman, AJ Jr, Wolff, J and Zajac, JM (2004) Search for nanosecond optical pulses from nearby solar-type stars. Astrophysical Journal 613, 1270.CrossRefGoogle Scholar
JPL (2000) DSN Telecommunications Link Design Handbook. Available at Scholar
Kardashev, NS (1964) Transmission of information by extraterrestrial civilizations. Soviet Astronomy 8, 217.Google Scholar
Kardashev, NS (1967) Transmission of information by extraterrestrial civilizations. In Tovmasyan, GM (ed.), Extraterrestrial Civilizations, NASA TTF–438, 19. Springfield, VA: NASA Scientific and Technical Information Facility translation, pp. 1929.Google Scholar
Kasting, JF, Whitmire, DP and Reynolds, RT (1993) Habitable zones around main sequence stars. Icarus 101, 108.CrossRefGoogle ScholarPubMed
Kipping, DM and Teachey, A (2016) A cloaking device for transiting planets. Monthly Notices of the Royal Astronomical Society 459, 1233.CrossRefGoogle Scholar
Kopparapu, RK, Ramirez, R, Kasting, JF, Eymet, V, Robinson, TD, Mahadevan, S, Terrien, RC, Domagal-Goldman, S, Meadows, V and Desphande, R (2013) Habitable zones around main-sequence stars: new estimates. Astrophysical Journal 765, 131.CrossRefGoogle Scholar
Korpela, E, Cobb, J, Werthimer, D and Lebofsky, M (2004) SETI@home Reobservation Report. Available at (Accessed 26 October 2016).Google Scholar
Korpela, E, Anderson, DP, Cobb, J, Howard, A, Lebofsky, M, Siemion, APV, von Korff, J and Werthimer, D (2011) Status of the UC-Berkeley SETI efforts. In Hoover, RB, Davies, PCW, Levin, GV and Rozanov, AY (eds). Instruments, Methods, and Missions for Astrobiology XIV, vol. 8152, Proc. of SPIE, pp. 316324.CrossRefGoogle Scholar
Kraus, JD (1994) The Tantalizing Wow Signal, NRAO Kraus Archive Range 6A Box 4 1994-01-30. Available at (Accessed 1 April 2017).Google Scholar
Lazio, TJW, Tarter, J and Backus, PR (2002) Megachannel extraterrestrial assay candidates: no transmissions from intrinsically steady sources. Astronomical Journal 124, 560.CrossRefGoogle Scholar
Leigh, D and Horowitz, P (2000) Strategies, implementation and results of BETA. In Guillermo Lemarchand, G and Meech, K (eds), Bioastronomy 99: A New Era in the Search for Life in the Universe, vol. 213, ASP Conference Series, San Francisco: Astronomical Society of the Pacific, pp. 459465.Google Scholar
Lightman, AP (1984) A fundamental determination of the planetary day and year. American Journal of Physics 52, 211.CrossRefGoogle Scholar
Maccone, C (2019) Moon farside protection, Moon Village and PAC (Protected Antipode Circle). Acta Astronautica 154, 233.CrossRefGoogle Scholar
Makovetskii, PV (1980) Mutual strategy of search for CETI call signals. Icarus 41(2), 178192. Scholar
Miguel, Y and Brunini, A (2010) Planet formation: statistics of spin rates and obliquities of extrasolar planets. Monthly Notices of the Royal Astronomical Society 406, 1935.Google Scholar
Nishino, Y and Seto, N (2018) The search for extra-galactic intelligence signals synchronized with binary neutron star mergers. Astrophysical Journal Letters 862, L21.CrossRefGoogle Scholar
Noyelles, B, Frouard, J, Makarov, V and Efroimsky, M (2014) Spin–orbit evolution of Mercury revisited. Icarus 241, 26.CrossRefGoogle Scholar
Oliver, BM (1993) Symmetry in SETI. In Shostak, S (ed.), Third Decennial US-USSR Conference on SETI, vol. 47, ASP Conf. Series, San Francisco: Astronomical Society of the Pacific, pp. 6772.Google Scholar
Oliver, BM and Billingham, J (1971) Project Cyclops: A Design Study for a System for Detecting Extraterrestrial Life, prepared under Stanford/NASA/Ames Research Center 1971 Summer Faculty Fellowship Program in Engineering Systems Design, NASA CR 114445, National Aeronautics and Space Administration, p. 31.Google Scholar
Pfleiderer, J (1988) Galactic communication with small duty cycles. In Shahrokhi, F, Chao, CC and Harwell, KE (eds), Commercial Opportunities in Space, AIAA Progress in Astronautics and Aeronautics, Reston VA:American Institute of Aeronautics and Astronautics, pp. 305318.Google Scholar
Price, DC, Enriquez, JE, Brzycki, B, Croft, S, Czech, D, DeBoer, D, DeMarines, J, Foster, G, Gajjar, V, Gizani, N, Hellbourg, G, Isaacson, H, Lacki, B, Lebofsky, M, MacMahon, DHE, de Pater, I, Siemion, APV, Werthimer, D, Green, JA, Kaczmarek, JF, Maddalena, RJ, Mader, S, Drew, J and Worden, SP (2020) The breakthrough listen search for intelligent life: observations of 1327 nearby stars over 1.10–3.45 GHz. Astrophysical Journal 159, 86.Google Scholar
Rebane, KK (1993) The search for extraterrestrial intelligence and ecological problems. In Shostak, S (ed.), Third Decennial US-USSR Conference on SETI ASP Conf. Series 47, San Francisco: Astronomical Society of the Pacific, pp. 219228.Google Scholar
Ross, M (2000) Search strategy for detection of SETI short pulse laser signals. In Lemarchand, G and Meech, K (eds), Bioastronomy '99: A New Era in Bioastronomy ASP Conf. Series 213, San Francisco: Astronomical Society of the Pacific, pp. 541557.Google Scholar
Sheikh, SZ, Wright, JT, Siemion, A and Enriquez, JE (2019) Choosing a maximum drift rate in a SETI search: astrophysical considerations. Astrophysical Journal 884, 14.CrossRefGoogle Scholar
Shostak, S (2009) New strategies for SETI. In Meech, KJ, Keane, JV, Mumma, MJ, Siefert, JL and Werthimer, DJ (eds). Bioastronomy 2007: Molecules, Microbes, and Extraterrestrial Life, ASP Conf. Series 420, San Francisco: Astronomical Society of the Pacific, pp. 403408.Google Scholar
Shostak, S (2011 a) Short-pulse SETI. Acta Astronautica 68, 362.CrossRefGoogle Scholar
Shostak, S (2011 b) Efficiency in SETI. Acta Astronautica 68, 347.CrossRefGoogle Scholar
Shostak, S and Villard, R (2002) A scheme for targeting optical SETI observations. In Norris, RP and Stootman, FH (eds), Bioastronomy 2002: Life Among the Stars, IAU Symposium 213, San Francisco: Astronomical Society of the Pacific, pp. 409413.Google Scholar
Siemion, APV, Bower, GC, Foster, G, McMahon, PL, Wagner, MI, Werthimer, D, Backer, D, Cordes, J and van Leeuwen, J (2012) The Allen telescope array fly's eye survey for fast radio transients. Astrophysical Journal 744, 109.CrossRefGoogle Scholar
Siemion, APV, Demorest, P, Korpella, E, Maddalena, RJ, Wertheimer, D, Cobb, J, Howard, AW, Langston, G, Lebofsky, M, Marcy, GW and Tarter, J (2013) A 1.1–1.9 GHz SETI survey of the Kepler field. I. A search for narrow-band emission from select targets. Astrophysical Journal 767, 94.CrossRefGoogle Scholar
Siemion, APV, Benford, J, Cheng-Jin, J, Chennamangalam, J, Cordes, J, DeBoer, DR, Falcke, H, Garrett, M, Garrington, S, Gurvits, L, Hoare, M, Korpela, EJ, Lazio, J, Messerschmitt, D, Morrison, IS, O’Brien, T, Paragi, Z, Penny, A, Spitler, L, Tarter, J and Werthimer, D (2014) Searching for extraterrestrial intelligence with the square kilometre array. Proceedings of Science, Advancing Astrophysics with the Square Kilometre Array, AASKA 14, 116.Google Scholar
Snellen, IAG, Brandl, BR, de Kok, RJ, Brogi, M, Birkby, J and Schwartz, H (2014) Fast spin of the young extrasolar planet β Pictoris b. Nature 509, 63.CrossRefGoogle Scholar
Sonett, CP, Kvale, EP, Zakharian, A, Chan, MA and Demko, TM (1996) Late proterozoic and paleozoic tides, retreat of the Moon, and rotation of the Earth, Science 273, 100104.CrossRefGoogle Scholar
Spitler, LG, Scholz, P, Hessels, JWT, Bogdanov, S, Brazier, A, Camilo, F, Chatterjee, S, Cordes, JM, Crawford, F, Deneva, J, Ferdman, RD, Freire, PCC, Kaspi, VM, Lazarus, P, Lynch, R, Madsen, EC, McLaughlin, MA, Patel, C, Ransom, SM, Seymour, A, Stairs, IH, Stappers, BW, van Leeuwen, J and Zhu, WW (2016) A repeating fast radio burst. Nature 531, 202.CrossRefGoogle ScholarPubMed
Sullivan, W (1991) Pan-galactic pulse periods and the pulse window for SETI. In Heidmann, J and Klein, MJ (eds). Bioastronomy: The Search for Extraterrestrial Life. Berlin: Springer-Verlag, pp. 259268.CrossRefGoogle Scholar
Sullivan, WT, Brown, C and Wetherill, C (1978) Eavesdropping: the radio signature of the Earth. Science (New York, NY) 199, 377.CrossRefGoogle Scholar
Tarter, J (1995) Summary of SETI Observing Programs. Mountain View, CA: SETI Institute. Available at (Accessed 29 July 2016).Google Scholar
Tarter, J (2001) The Search for Extraterrestrial Intelligence (SETI). Annual Review of Astronomy and Astrophysics 39, 511.CrossRefGoogle Scholar
Tarter, J (2011) ATA: a cyclops for the 21st century. In Shuch, HP (ed). Searching for Extraterrestrial Intelligence: Past, Present, and Future. Chichester UK: Springer Praxis, pp. 131145.CrossRefGoogle Scholar
Thornton, D, Stappers, B, Bailes, M, Barsdell, B, Bates, S, Bhat, NDR, Burgay, M, Burke-Spolaor, S, Champion, DJ, Coster, P, D'Amico, N, Jameson, A, Johnston, S, Keith, M, Kramer, M, Levin, L, Milia, S, Ng, C, Possenti, A and van Straten, W (2013) A population of fast radio bursts at cosmological distances. Science (New York, NY) 341, 53.CrossRefGoogle ScholarPubMed
Tingay, SJ, Tremblay, C, Walsh, A and Urquhart, R (2016) An opportunistic Search for Extraterrestrial Intelligence (SETI) with the Murchison Widefield Array. Astrophysical Journal Letters 827, L22.CrossRefGoogle Scholar
Welch, J, Backer, D, Blitz, L, Bock, D, Bower, GC, Cheng, C, Croft, S, Dexter, M, Engargiola, G, Fields, E, Forster, J, Gutierrez-Kraybill, C, Heiles, C, Helfer, T, Jorgensen, S, Keating, G, Lugten, J, MacMahon, D, Milgrome, O, Thornton, D, Urry, L, van Leeuwen, J, Werthimer, D, Williams, PH, Wright, M, Tarter, J, Ackermann, R, Atkinson, S, Backus, P, Barott, W, Bradford, T, Davis, M, DeBoer, D, Dreher, J, Harp, G, Jordan, J, Kilsdonk, T, Pierson, T, Randall, K, Ross, J, Shostak, S, Fleming, M, Cork, C, Vitouchkine, A, Wadefalk, N and Weinreb, S (2009) The Allen telescope array: the first widefield, panchromatic, snapshot radio camera for radio astronomy and SETI. Proceedings of the IEEE 97, 1438.CrossRefGoogle Scholar
Williams, GE (2000) Geological constraints on the Precambrian history of Earth's rotation and the Moon's orbit. Reviews of Geophysics 38, 37. Available at Scholar
Wright, JT (2017) Exoplanets and SETI. In Deeg, H and Belmonte, J (eds). Handbook of Exoplanets. Cham: Springer, pp. 34053412.Google Scholar
Zombeck, MV (2007) Handbook of Space Astronomy & Astrophysics, 3rd Edn.Cambridge University Press.Google Scholar
Cited by

Send article to Kindle

To send this article to your Kindle, first ensure is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

Note you can select to send to either the or variations. ‘’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Intermittent signals and planetary days in SETI
Available formats

Send article to Dropbox

To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

Intermittent signals and planetary days in SETI
Available formats

Send article to Google Drive

To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

Intermittent signals and planetary days in SETI
Available formats

Reply to: Submit a response

Please enter your response.

Your details

Please enter a valid email address.

Conflicting interests

Do you have any conflicting interests? *