- Person
- Carl Sagan
- Lived
- 1934–1996
- Field
- Astronomy, planetary science
- From
- American
The story
Pioneer 10, launched on March 2, 1972, and Pioneer 11, launched on April 5, 1973, were among the first human-made objects to reach the speed needed to escape the solar system. Eric Burgess, visiting the Jet Propulsion Laboratory during the Mariner 9 mission, suggested that they should carry a message from humanity. He took the idea to Carl Sagan, who had lectured about communicating with extraterrestrial intelligence at a conference in Crimea.
Sagan was enthusiastic. NASA agreed to the plan and gave him three weeks to prepare it. Together with the astronomer Frank Drake he designed a gold-anodised aluminium plaque, with artwork by Linda Salzman Sagan, his wife at the time. It was mounted on each spacecraft's antenna supports, where it would be shielded from interstellar dust.
The design uses science as a common language. A symbol at the top shows the hyperfine transition of hydrogen, the most common element in the universe, which provides a unit of length and a unit of time for the rest of the plaque. A man and a woman stand in front of an outline of the spacecraft, drawn to scale so that their height can be worked out, with the man's hand raised in greeting. A radial map shows the Sun's position relative to fourteen pulsars, each labelled with its period in binary code, so that a finder could locate the solar system and even estimate when the craft was launched. Along the bottom, a diagram of the solar system traces the spacecraft's path past Jupiter.
The plaque drew debate on Earth as well, from arguments about the nude figures to questions about whether an alien would understand an arrow. Sagan regretted that the figures did not look as broadly representative of humanity as he had intended. He saw the plaque as a message in a bottle, unlikely ever to be found but sent with hope.
It was the first physical message sent into space, and it set the pattern for what followed. Sagan refined his ideas for the Voyager Golden Record of 1977, which carried the same pulsar map on its cover. Both Pioneer spacecraft are now heading out of the solar system into interstellar space, carrying their greeting with them.
Why it matters
The Pioneer plaque was humanity's first message sent beyond the solar system, and its pulsar map and scientific language became the model for later messages such as the Voyager Golden Record.
About Carl Sagan
Brooklyn-born astronomer who explained the Venus greenhouse, helped send humanity’s messages on Pioneer and Voyager, and taught Cosmos viewers worldwide to look at the universe with wonder and doubt.
More about Carl Sagan
- Carl Sagan co-founded the Planetary SocietyIn 1980 Carl Sagan co-founded the Planetary Society and became its first president, building a public movement to support the exploration of space.
- Carl Sagan explained why Venus is a furnaceIn the early 1960s Carl Sagan argued from radio data that Venus's surface was about 500 °C because of a greenhouse effect, a conclusion confirmed by Mariner 2 in 1962.
- Carl Sagan inspired a generation of science communicatorsCarl Sagan invited a 17-year-old Neil deGrasse Tyson to Cornell and taught Bill Nye astronomy, inspiring a generation of scientists and science popularisers.
- Carl Sagan showed Mars's changing colours were dustMany astronomers thought seasonal colour changes on Mars were spreading vegetation. Carl Sagan showed they were shifts in surface dust driven by windstorms.
- Carl Sagan asked Voyager to photograph the Pale Blue DotAt Carl Sagan's urging, Voyager 1 turned its camera homeward on February 14, 1990, and photographed Earth from about 6 billion kilometres away as a tiny pale blue dot.
- Carl Sagan made the search for alien life respectableIn 1982 Carl Sagan published a petition in the journal Science supporting the search for extraterrestrial intelligence, signed by 70 scientists including seven Nobel laureates.
- Carl Sagan foresaw ocean worlds on Titan and EuropaCarl Sagan was among the first to suggest that Saturn's moon Titan might have surface liquids and that Jupiter's moon Europa might hide an ocean of water beneath its ice.
- Carl Sagan chaired the Voyager Golden Record committeeFor the Voyager probes launched in 1977, Carl Sagan chaired the committee that chose the Golden Record's contents, including greetings in 55 languages and 116 images of Earth.
- Carl Sagan warned Congress about climate change in 1985Drawing on his study of Venus, Carl Sagan testified to the US Congress in 1985 that the greenhouse effect would change Earth's climate.
- Kip Thorne helped Carl Sagan imagine Contact's wormholesFor his 1985 novel Contact, Carl Sagan asked his friend Kip Thorne how a wormhole might work. The book sold 1.7 million copies in two years and became a 1997 film.
- Carl Sagan's Cosmos reached 500 million peopleCosmos: A Personal Voyage, first broadcast in 1980, has been seen by at least 500 million people in 60 countries, and its companion book was the best-selling science book of its time.
- Carl Sagan won a Pulitzer Prize for The Dragons of EdenCarl Sagan's 1977 book The Dragons of Eden, on the evolution of human intelligence, won the 1978 Pulitzer Prize for General Nonfiction and introduced his Cosmic Calendar.
- Carl Sagan gave the public a baloney detection kitIn The Demon-Haunted World (1995), Carl Sagan offered readers a toolkit for critical thinking and popularised the rule that extraordinary claims require extraordinary evidence.
- Carl Sagan warned the world about nuclear winterIn 1983 Carl Sagan co-authored the TTAPS study warning that a nuclear war could cool the planet, work honoured in 2022 with the Future of Life Award.
Sources
- Pioneer plaque Wikipedia
- Carl Sagan Wikipedia
Another act of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.