Active SETI (Active Search for Extra-Terrestrial Intelligence) is the attempt to send messages to intelligent aliens. Active SETI messages are usually in the form of radio signals, however, physical messages like that of the Pioneer plaque may also be considered an active SETI message. The Pioneer plaques are a pair of Gold anodized Aluminum plaques which were placed on board the 1972 Pioneer 10 and 1973 Active SETI is also known as METI (Messaging to Extra-Terrestrial Intelligence), or positive SETI. Active SETI is contrasted to passive SETI, which only searches for signals, without any attempt to send them. Search for Extra-Terrestrial Intelligence ( SETI) is the collective name for a number of activities to detect intelligent Extraterrestrial life.

The term METI was coined by Russian scientist Alexander Zaitsev, who denoted the clear-cut distinction between Active SETI and METI:^[1]

The science known as SETI deals with searching for messages from aliens. Aleksandr Leonidovich Zaitsev (Александр Леонидович Зайцев b METI science deals with the creation of messages to aliens. Thus, SETI and METI proponents have quite different perspectives. SETI scientists are in a position to address only the local question “does Active SETI make sense?” In other words, would it be reasonable, for SETI success, to transmit with the object of attracting ETI’s attention? In contrast to Active SETI, METI pursues not a local, but a more global purpose – to overcome the Great Silence in the Universe, bringing to our extraterrestrial neighbors the long-expected annunciation “You are not alone!”

Contents 1 Message construction 2 Realized projects 3 Perceived risk 4 Beacon proposal 5 References

Message construction

The lack of an established communications protocol is a challenge for METI. In the field of Telecommunications, a communications protocol is the set of standard rules for data representation signaling authentication and error detection required to

Also characteristics of the radio signal such as wavelength, type of polarization, and modulation have to be considered.

Realized projects

• Arecibo Message (1974)
• Cosmic Call 1 (1999)
• Teen Age Message (2001)
• Cosmic Call 2 (2003)

These projects have targeted stars between 32 and 69 light-years from the Earth. The Arecibo message was beamed via frequency modulated Radio waves into space at a ceremony to mark the remodeling of the Arecibo radio telescope The Teen Age Message (TAM was an METI message transmitted from Evpatoria Planetary Radar to 6 nearby Sun-like stars during August-September 2001 The exception is the Arecibo message, which targeted Glob cluster M13, approximately 24000 light-years away. The Arecibo message was beamed via frequency modulated Radio waves into space at a ceremony to mark the remodeling of the Arecibo radio telescope The Great Globular Cluster in Hercules (also known as the Hercules Globular Cluster, Messier Object 13, Messier 13, M13, or NGC 6205 The first message to reach its destination will be Cosmic Call 2, which should reach Hip 4872 of Cassiopeia in April 2036. Cassiopeia ( colloquially /ˌkæsiˈoʊpiə/ is a northern Constellation which Greek mythology considered to represent the vain queen Cassiopeia who boasted

Stars to which messages were sent, are the following:^[2][3]

Name	Designation	Constellation	Date sent	Arrival date	Message
Messier 13	NGC 6205	Hercules	1974-11-16November 16, 1974	approx. The Great Globular Cluster in Hercules (also known as the Hercules Globular Cluster, Messier Object 13, Messier 13, M13, or NGC 6205 Hercules (ˈhɝkjəliːz ˈhɝkjuːliːz is the fifth largest of the 88 modern Constellations It was also one of Ptolemy 's 48 constellations Events 534 - A second and final revision of the Codex Justinianus is published Year 1974 ( MCMLXXIV) was a Common year starting on Tuesday (link will display full calendar of the 1974 Gregorian calendar. 25974	Arecibo Message
16 Cyg A	HD 186408	Cygnus	1999-05-24May 24, 1999	2069-11November 2069	Cosmic Call 1
15 Sge	HD 190406	Sagitta	1999-06-30June 30, 1999	2057-02February 2057	Cosmic Call 1
	HD 178428	Sagitta	1999-06-30June 30, 1999	2067-10October 2067	Cosmic Call 1
Gl 777	HD 190360	Cygnus	1999-07-01July 1, 1999	2051-04April 2051	Cosmic Call 1
	HD 197076	Delphinus	2000-08-29August 29, 2001	2070-02February 2070	Teen Age Message
47 UMa	HD 95128	Ursa Major	2001-09-03September 3, 2001	2047-07July 2047	Teen Age Message
37 Gem	HD 50692	Gemini	2001-09-03September 3, 2001	2057-12December 2057	Teen Age Message
	HD 126053	Virgo	2001-09-03September 3, 2001	2059-12January 2059	Teen Age Message
	HD 76151	Hydra	2001-09-04September 4, 2001	2057-05May 2057	Teen Age Message
	HD 193664	Draco	2001-09-04September 4, 2001	2059-01January 2059	Teen Age Message
	HIP 4872	Cassiopeia	2003-07-06July 6, 2003	2036-04April 2036	Cosmic Call 2
	HD 245409	Orion	2003-07-06July 6, 2003	2040-08August 2040	Cosmic Call 2
55 Cnc	HD 75732	Cancer	2003-07-06July 6, 2003	2044-05May 2044	Cosmic Call 2
	HD 10307	Andromeda	2003-07-06July 6, 2003	2044-09September 2044	Cosmic Call 2
47 UMa	HD 95128	Ursa Major	2003-07-06July 6, 2003	2049-05May 2049	Cosmic Call 2

Perceived risk

Active SETI has been heavily criticized due to the perceived risk of revealing the location of the Earth to alien civilizations, without some process of prior international consultation. The Arecibo message was beamed via frequency modulated Radio waves into space at a ceremony to mark the remodeling of the Arecibo radio telescope The Henry Draper Catalogue ( HD) is an Astronomical Star catalogue published between 1918 and 1924 giving Spectroscopic classifications Cygnus (ˈsɪgnəs Swan, Κύκνος) is a northern Constellation. Events 1218 - The Fifth Crusade leaves Acre for Egypt. 1276 - Magnus Ladulås is crowned Year 1999 ( MCMXCIX) was a Common year starting on Friday (link will display full 1999 Gregorian calendar) Notable predictions and known events 2061 Expected expiration of the Singapore-Malaysia Water Agreement. The Henry Draper Catalogue ( HD) is an Astronomical Star catalogue published between 1918 and 1924 giving Spectroscopic classifications This article is about the constellation for the trigonometric function see Versine. Events 350 - Roman usurper Nepotianus, of the Constantinian dynasty, is defeated and killed by troops of the Usurper Year 1999 ( MCMXCIX) was a Common year starting on Friday (link will display full 1999 Gregorian calendar) This is an article about the year 2057 For the television show see 2057 (TV series. The Henry Draper Catalogue ( HD) is an Astronomical Star catalogue published between 1918 and 1924 giving Spectroscopic classifications This article is about the constellation for the trigonometric function see Versine. Events 350 - Roman usurper Nepotianus, of the Constantinian dynasty, is defeated and killed by troops of the Usurper Year 1999 ( MCMXCIX) was a Common year starting on Friday (link will display full 1999 Gregorian calendar) Notable predictions and known events 2061 Expected expiration of the Singapore-Malaysia Water Agreement. Gliese 777, often abbreviated as Gl 777 and or GJ 777, is a Yellow subgiant approximately 52 Light-years away in the Constellation The Henry Draper Catalogue ( HD) is an Astronomical Star catalogue published between 1918 and 1924 giving Spectroscopic classifications Cygnus (ˈsɪgnəs Swan, Κύκνος) is a northern Constellation. "July 1st" redirects here For the Ayumi Hamasaki song see H (song. Year 1999 ( MCMXCIX) was a Common year starting on Friday (link will display full 1999 Gregorian calendar) 2051 ( MMLI) will be a Common year starting on Sunday of the Gregorian calendar. The Henry Draper Catalogue ( HD) is an Astronomical Star catalogue published between 1918 and 1924 giving Spectroscopic classifications Delphinus (dɛlˈfaɪnəs Dolphin) is a rather small (ranked 69th northern Constellation very close to the Celestial equator. Events 708 - Copper coins are minted in Japan for the first time (Traditional Japanese date: August 10, 708) Year 2001 ( MMI) was a Common year starting on Monday according to the Gregorian calendar. Notable predictions and known events 2070 February - An Active SETI message called Teen Age Message sent from the 70-meter Eupatoria The Teen Age Message (TAM was an METI message transmitted from Evpatoria Planetary Radar to 6 nearby Sun-like stars during August-September 2001 47 Ursae Majoris, often abbreviated as 47 UMa, is a Solar twin, Yellow dwarf Star approximately 46 Light-years away in the Constellation The Henry Draper Catalogue ( HD) is an Astronomical Star catalogue published between 1918 and 1924 giving Spectroscopic classifications Ursa Major ( is a Constellation visible throughout the year in most of the northern hemisphere Events 36 BC - In the Battle of Naulochus, Marcus Vipsanius Agrippa, Admiral of Octavian, defeats Sextus Pompeius Year 2001 ( MMI) was a Common year starting on Monday according to the Gregorian calendar. 2047 ( MMXLVII) will be a Common year starting on Tuesday of the Gregorian calendar. The Teen Age Message (TAM was an METI message transmitted from Evpatoria Planetary Radar to 6 nearby Sun-like stars during August-September 2001 37 Geminorum is a Star located at the northwest part of the Constellation Gemini. The Henry Draper Catalogue ( HD) is an Astronomical Star catalogue published between 1918 and 1924 giving Spectroscopic classifications Gemini (ˈgɛmɪnaɪ Twins, symbol, Unicode ♊ is one of the Constellations of the Zodiac known as "the twins" Events 36 BC - In the Battle of Naulochus, Marcus Vipsanius Agrippa, Admiral of Octavian, defeats Sextus Pompeius Year 2001 ( MMI) was a Common year starting on Monday according to the Gregorian calendar. This is an article about the year 2057 For the television show see 2057 (TV series. The Teen Age Message (TAM was an METI message transmitted from Evpatoria Planetary Radar to 6 nearby Sun-like stars during August-September 2001 The Henry Draper Catalogue ( HD) is an Astronomical Star catalogue published between 1918 and 1924 giving Spectroscopic classifications Virgo ( Virgin, symbol, Unicode ♍ is a Constellation of the Zodiac. Events 36 BC - In the Battle of Naulochus, Marcus Vipsanius Agrippa, Admiral of Octavian, defeats Sextus Pompeius Year 2001 ( MMI) was a Common year starting on Monday according to the Gregorian calendar. 2059 ( MMLIX) will be a Common year starting on Wednesday of the Gregorian calendar. The Teen Age Message (TAM was an METI message transmitted from Evpatoria Planetary Radar to 6 nearby Sun-like stars during August-September 2001 The Henry Draper Catalogue ( HD) is an Astronomical Star catalogue published between 1918 and 1924 giving Spectroscopic classifications Hydra (ˈhaɪdrə is the largest of the 88 modern Constellations and was also one of the 48 constellations listed by Ptolemy. Events 476 - Romulus Augustus, last emperor of the Western Roman Empire, is deposed when Odoacer proclaims himself Year 2001 ( MMI) was a Common year starting on Monday according to the Gregorian calendar. This is an article about the year 2057 For the television show see 2057 (TV series. The Teen Age Message (TAM was an METI message transmitted from Evpatoria Planetary Radar to 6 nearby Sun-like stars during August-September 2001 The Henry Draper Catalogue ( HD) is an Astronomical Star catalogue published between 1918 and 1924 giving Spectroscopic classifications Draco (ˈdreɪkoʊ Dragon) is a far northern Constellation that is circumpolar for many Northern hemisphere observers Events 476 - Romulus Augustus, last emperor of the Western Roman Empire, is deposed when Odoacer proclaims himself Year 2001 ( MMI) was a Common year starting on Monday according to the Gregorian calendar. 2059 ( MMLIX) will be a Common year starting on Wednesday of the Gregorian calendar. The Teen Age Message (TAM was an METI message transmitted from Evpatoria Planetary Radar to 6 nearby Sun-like stars during August-September 2001 The Hipparcos and Tycho Catalogues (Tycho-1 are the primary products of the European Space Agency 's astrometric mission Hipparcos. Cassiopeia ( colloquially /ˌkæsiˈoʊpiə/ is a northern Constellation which Greek mythology considered to represent the vain queen Cassiopeia who boasted Events 1044 - The Battle of Ménfő takes place 1189 - Richard the Lionheart is crowned King of England Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. 2036 ( MMXXXVI) will be a Leap year starting on Tuesday of the Gregorian calendar. The Henry Draper Catalogue ( HD) is an Astronomical Star catalogue published between 1918 and 1924 giving Spectroscopic classifications Orion (ɒˈraɪən a Constellation often referred to as The Hunter, is a prominent constellation one of the largest and perhaps the best-known and most conspicuous Events 1044 - The Battle of Ménfő takes place 1189 - Richard the Lionheart is crowned King of England Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. 2040 ( MMXL) will be a Leap year starting on Sunday of the Gregorian calendar. 55 Cancri (ˈkæŋkraɪ or /ˈkæŋkriː/ also catalogued Rho1 Cancri or abbreviated 55 Cnc, is a Binary star approximately 41 Light-years The Henry Draper Catalogue ( HD) is an Astronomical Star catalogue published between 1918 and 1924 giving Spectroscopic classifications Cancer ( Crab, symbol, Unicode ♋ is one of the twelve Constellations of the Zodiac. Events 1044 - The Battle of Ménfő takes place 1189 - Richard the Lionheart is crowned King of England Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. 2044 ( MMXLIV) will be a Leap year starting on Friday of the Gregorian calendar. HD 10307 (aka HR 483 A) is a star similar to the sun in mass temperature and metal content situated about 41 light-years from Earth in the constellation Andromeda ( is a Constellation named for the princess Andromeda ( Greek Ανδρομέδη = guardian of the men) a character in Events 1044 - The Battle of Ménfő takes place 1189 - Richard the Lionheart is crowned King of England Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. 2044 ( MMXLIV) will be a Leap year starting on Friday of the Gregorian calendar. 47 Ursae Majoris, often abbreviated as 47 UMa, is a Solar twin, Yellow dwarf Star approximately 46 Light-years away in the Constellation The Henry Draper Catalogue ( HD) is an Astronomical Star catalogue published between 1918 and 1924 giving Spectroscopic classifications Ursa Major ( is a Constellation visible throughout the year in most of the northern hemisphere Events 1044 - The Battle of Ménfő takes place 1189 - Richard the Lionheart is crowned King of England Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. 2049 ( MMXLIX) will be a Common year starting on Friday of the Gregorian calendar.

But some consider this as panic and irrational superstition, see: Sending and Searching for Interstellar Messages

To lend a quantitative basis to discussions of the risks of transmitting deliberate messages from Earth, the SETI Permanent Study Group of the International Academy of Astronautics [1] adopted in 2007 a new analytical tool, the San Marino Scale [2]. Developed by Prof. Ivan Almar and Prof. H. Paul Shuch, the San Marino Scale evaluates the significance of transmissions from Earth as a function of signal intensity and information content. Dr H Paul Shuch ( May 23, 1946) is an American Scientist and Engineer who has coordinated Radio amateurs to help in the Its adoption suggests that not all such transmissions are created equal, thus each must be evaluated on a case-by-case basis before establishing blanket international policy regarding Active SETI.

Beacon proposal

One proposal for a 10 billion watt interstellar SETI beacon was dismissed by Robert A. Freitas Jr. to be infeasible for a pre-Type I civilization on the Kardashev scale. Robert A Freitas Jr is a Senior Research Fellow one of four researchers at the nonprofit foundation Institute for Molecular Manufacturing (IMM in Palo Alto, The Kardashev scale is a method of measuring a civilization's level of technological advancement ^[4] However, this argument, dated from 1980, assumes omni-directional beacons, which may not be the best way to proceed. As a result it has been suggested that civilizations must advance into Type I before the energy required for reliable contact with other civilizations. Advances in consumer electronics have made possible cheaper transmitters. ^[5] This can reduce the power and cost to levels that are reasonable with current (2008) earth technology.

Once civilizations have discovered each others' locations, the energy requirements for maintaining contact and exchanging information can be significantly reduced through the use of highly directional transmission technologies. In 1974, the Arecibo Observatory transmitted a message toward the M13 globular cluster about 25,000 light-years away, for example, and the use of larger antennas or shorter wavelengths would allow transmissions of the same energy to be focused on even more remote targets, such as those attempted by Active SETI. The Arecibo Observatory is a very sensitive Radio telescope located approximately south-southwest from the town of Arecibo in Puerto Rico. The Great Globular Cluster in Hercules (also known as the Hercules Globular Cluster, Messier Object 13, Messier 13, M13, or NGC 6205

References

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