Timeline
Messages humanity has sent to space.
Since the 1960s humanity has sent a small number of deliberate messages beyond Earth: radio messages aimed at planets and stars, and engraved plaques and Golden Records on spacecraft. This timeline lists the best known, each with a source. None has received a reply.
The timeline.
- 1962Morse message
In November 1962 the Soviet planetary radar at Yevpatoria sent three words in Morse code toward Venus: Mir, which means both peace and world, then Lenin and USSR. It was a radar test: the signal bounced off Venus and was received back on Earth. The institute that sent it calls it a forerunner of interstellar messages, not a true one.
- 1972Pioneer plaques
Pioneer 10 launched on 2 March 1972 carrying a gold-anodized plaque with drawings of a man and a woman, the solar system and the Sun's position relative to 14 pulsars, with the hydrogen transition as its unit. Pioneer 11 followed on 5 April 1973 with the same plaque. Designed by Carl Sagan and Frank Drake, artwork by Linda Salzman Sagan.
- 1974Arecibo message
On 16 November 1974 the Arecibo telescope sent 1,679 bits at 2380 MHz toward the globular cluster M13, about 25,000 light-years away, once, in about three minutes.
- 1977Voyager Golden Records
Voyager 2 (20 August 1977) and Voyager 1 (5 September 1977) each carry a record with 115 images, greetings in 55 languages and music from many cultures and eras, plus printed messages from President Jimmy Carter and UN Secretary-General Kurt Waldheim.
- 1999Cosmic Call 1
Sent on 24 May and 30 June 1999 from the RT-70 radio telescope at Yevpatoria, Ukraine. Organized by the Texas company Team Encounter, with much of the money from small donations; its scientific primer was written by Yvan Dutil and Stéphane Dumas, and Alexander Zaitsev oversaw the transmission.
- 2003Cosmic Call 2
Sent on 6 July 2003 from the same telescope in Yevpatoria, to five more stars.
- 2008Across the Universe
On 4 February 2008 NASA beamed the Beatles song Across the Universe toward the star Polaris from a Deep Space Network antenna near Madrid, Spain, to mark NASA's 50th anniversary.
- 2008A Message from Earth
On 9 October 2008, 501 messages chosen in a competition on the social network Bebo were sent from Yevpatoria to the planet Gliese 581c, about 20 light-years away.
- 2009Hello from Earth
On 28 August 2009, 25,880 messages from the public were sent from the Canberra Deep Space Communication Complex in Australia to Gliese 581d, a National Science Week initiative of COSMOS magazine with the support of NASA and CSIRO.
- 2013Lone Signal
Launched on 17 June 2013 from the Jamesburg Earth Station in California, beaming public messages toward Gliese 526, about 18 light-years away. The first message was free, further ones were paid.
- 2017Sónar Calling GJ 273b
Sent on 16 to 18 October 2017 from the EISCAT antenna in Tromsø, Norway, to the planet GJ 273b at Luyten's Star, 12.4 light-years away, with music commissioned as a tribute to the Sónar festival. Organized by Sónar, the Institute of Space Studies of Catalonia and METI International.
- 2022Beacon in the Galaxy (proposal)
A team led by Jonathan Jiang of NASA's Jet Propulsion Laboratory proposed a new binary message for a possible future transmission. As far as published sources show, it has not been sent.
Who decides what we send?
No one, formally. Most messages so far were sent by scientists, companies or festivals. The rules scientists have agreed for replying to a detection, and the case against sending at all, are on the page How to contact aliens.
Why a letter, not a beam.
Every radio message on this list is a shout toward one point in the sky. Most will travel for decades or millennia before anyone could hear them. A letter on the web is closer: it is already where people look and where machines read.
Questions you may have.
What was the first message sent to aliens?
The first message made for other civilizations was the plaque on Pioneer 10, launched in 1972, and the first deliberate radio message was the Arecibo message of 16 November 1974. A Soviet radar test in November 1962 had already sent the Morse words Mir, Lenin and USSR toward Venus; its makers call it a forerunner, not a true interstellar message.
What did the Arecibo message say?
Its 1,679 bits form a picture 23 bits wide and 73 high. It shows the numbers one to ten, the elements that make up DNA, the formulas of its building blocks and its double helix, a human figure, the solar system and the Arecibo telescope. It was sent toward the star cluster M13.
What is on the Voyager Golden Record?
115 images, spoken greetings in 55 languages, music from many cultures and eras, and printed messages from President Jimmy Carter and UN Secretary-General Kurt Waldheim.
Has any message to space received a reply?
No. None of the messages listed here has received a confirmed reply.
When will the messages arrive?
Radio travels at the speed of light, so a message reaches its target after as many years as the target is light-years away. A message to a planet 20 light-years away arrives after 20 years. The Arecibo message reaches the distance of M13 after about 25,000 years, by which time the cluster will have moved out of its path.