Today is the 35th anniversary of the launching of Voyager 1, which is on the verge of becoming the first man-made object to leave our solar system. Its twin, Voyager 2, also celebrated its anniversary two weeks ago.
Their original missions were to tour Jupiter and Saturn. Both gathered information and sent back startling photos of erupting volcanoes on Io, signs of methane rain on Titan, and the possibility of an ocean below the surface of Europa.
Following their Jupiter/Saturn missions, Voyager 1 used Saturn as a gravitational slingshot and launched itself towards the edge of our solar system. It is currently 11 billion miles from our sun, while Voyager 2 continued on to Uranus and Neptune and is now around 9 billion miles from our sun.
Back in 1977, no one had any idea how long the spacecrafts would continue to transmit a signal. Both are still utilizing 1977 technology, and has only 68 kilobytes of computer memory and an eight-track tape recorder at its disposal. By comparison, the smallest iPod (an 8-gigabyte Nano) is 100,000 times more powerful.
Although neither spacecraft still beams photographs back to Earth, a handful of engineers still tend to them from a satellite campus near the NASA Jet Propulsion Laboratory. Twenty part-time scientists also analyze the data that streams back (a 17-hour trip for the radio signal from Voyager 1, and a 13 hour trip for Voyager 2).
Each spacecraft contains five working instruments that study magnetic fields, cosmic rays, and solar wind particles. Each also carries multi-lingual greetings, pictures and music on a disc – Greetings From Earth, just in case some distant neighbor stumbles across it.
Each spacecraft has enough fuel to last until about 2020, at which point Voyager 1 will have escaped our galaxy and given us a glimpse of what lies between us and our neighbors.