As I mentioned in my previous blogs on the Voyager space probes (here and here), I am talking about these envoys of humanity on live TV this Thursday (4th of October). The third and last part of my blogs about them concerns their journey beyond Neptune, the last planet Voyager 2 visited in 1989.
Prior to the Voyager space probes, NASA sent Pioneer 10 and 11 to Jupiter and Saturn and on into interstellar space in 1972 and 1973 respectively. Knowing that Pioneer could possibly travel to nearby stars one day, they were both fitted with a gold plaque showing where the probes had come from, and a cartoon of a naked man and woman to show what humans beings looked like.
When NASA’s JPL changed the flight path of Voyager 1 to take a closer look at Titan, Saturn’s largest moon, they knew the manoeuvre would take Voyager 1 out of the plane of the ecliptic. Voyager 2 continued on after Saturn to visit Uranus and Neptune. But, from the mission’s inception, scientists knew that both probes would continue on towards the outer reaches of our Solar System, and in into interstellar space, once their visit to the outer ice giant planets was complete.
To this end, Voyager 1 and Voyager 2 are carrying gold records, the idea being that any extra-terrestrial civilisations which come across them will be able to learn about Earth and the life on Earth. A committee, chaired by renowned planetary scientist Carl Sagan, was formed to decide what information the records should contain. Sagan and his fellow scientists assembled 116 images and a variety of natural sounds such as surf, wind, thunder etc. Also, the records contain the sounds of various animals (including birds), and greetings in 55 languages. There is also a selection of music from different cultures and eras.
Perhaps Voyager’s greatest legacy is the image which became known as the Pale Blue Dot. This is an image of Earth, taken by Voyager 1 in 1990, from a distance of some 6 billion kms away. It was Carl Sagan’s idea to take this picture of Earth from such a vast distance. It is the most distant image of Earth ever taken, and our home planet is just one tiny pixel in the image.
If this image of our home planet isn’t moving enough, the text that Carl Sagan put together to go with it is, in my opinion, one of the most moving pieces of prose ever written.
To quote just a part of his wonderful text
Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there-on a mote of dust suspended in a sunbeam.
As of writing this blog (2nd of October 2012), Voyager 1 is 18,304,000,000 km (18.3 billion km) from Earth, and Voyager 2 is 14,900,000,000 km (14.9 billion km) away. They really are our first interstellar messengers. Perhaps Voyager’s greatest legacy will not be the studies it made of the gas giant planets, but rather this image of our tiny world, showing how insignificant we really are in the grand scheme of things.