Voyager 1, a spindly object half the weight of the average family car has become the fastest machine ever made by man and has extended human reach for the first time beyond the boundaries of the solar system. It makes history every day by recording details of the interstellar environment and radioing them back to Earth.
NASA announced last month that Voyager 1 has entered interstellar space, passing beyond the reach of the energy radiated by the sun, known as the “solar wind.” Beyond the boundary known as the “heliopause,” Voyager 1 came into contact with the energy that flows between stars, known as the interstellar wind. The announcement was followed by release of a photograph of a “pale blue dot” representing Voyager 1’s radio signal detected by NASA radio-telescopes on Earth from the distance of 11.5 billion miles.
The photograph was reminiscent of, and the compliment to, a photograph taken by Voyager 1 in 1990, known as the “portrait of the solar system” in which Earth famously appears as a “pale blue dot.”
The public hadn’t heard much about Voyager 1 and its sister ship, Voyager 2, since that photograph, taken when they passed beyond the orbit of Pluto 23 years ago. That is because of the huge distances between the “milestones” of their journey. Both were launched in 1977 to explore Jupiter and Saturn, a mission they completed in 1980. Then they went on to look at the most distant planet, Neptune, in 1990 and have continued their outward journey at current speeds of more than 38,000 miles an hour. (At that speed it would take about 2 hours to go three times around the Earth.)
In crossing the “heliopause” Voyager 1 sent back the first data on the dimensions of the solar system inside that boundary. When Voyager 2 reaches the heliopause, it will add further data.
But beyond the heliopause the sun’s gravitational influence extends out to and beyond the “Oort cloud” of comets, and NASA estimates it will take Voyager another 200 to 300 years to reach the nearer edge of the Oort cloud and 30,000 years to pass beyond it. At that time it will be only halfway to Proxima Centauri, the nearest star to the sun.
Voyager’s ability to communicate with earth will be long gone by then; the fuel to run its radio is estimated to last only until 2025. But both editions of the spacecraft carry a gold-plated “audio-visual disc” for communicating with extraterrestrial life forms. It includes a mixed bag of somewhat dated messages including greetings from Jimmy Carter and recordings ranging from Australian aboriginal and African pygmy songs to blues, Bach, Beethoven and “Johnny B. Goode” by Chuck Berry.
Maybe some day we will hear back. Even so, there might be some communication problems.
Can you imagine an E.T. holding up a picture of Jimmy Carter and saying, “Take me to your leader”?