Over half of the almost seven billion people living today were not even born in 1977. In that year, NASA launched Voyager I and sent her out to explore our solar system. She weighed about as much as the Volkswagen Bug of that year. Today, at 34 years of age, she has lost some weight (burned up the hydrazine fuel), and is moving along at a steady 38,000 mph. On this, our 4th of July, she, and her sister ship, Voyager II, mark a freedom never before encountered in the history of mankind. They are leaving our solar system.
The original plan was to take advantage of a rare arrangement of the outer planets during the 1980’s and send these satellites to tour Jupiter (1979) and Saturn (1980). They happened to visit Jupiter’s moon, Io, just as a volcano was exploding, and they caught the event on camera. They discovered that Jupiter also has rings. They mapped details of the rings of Saturn, first observed by Galileo Galilei in 1610. Skillful navigation allowed the two spacecraft to add a tour of Uranus (1986) and Neptune (1989). Then, they headed for the great beyond.
Each Voyager carries a gold-plated audio-visual disc in the imagined event that the spacecraft is found by intelligent life-forms (a standard PR ploy of NASA). A Star Trek movie ran with this notion and, in the projected year 2273, had a Voyager 6 evolve into the intelligent, but errant, V’Ger life-form. The disc contains recorded greetings from earth VIPs (now scarcely remembered) and a medley of sounds that includes a whale, a baby crying, waves breaking on the shore, and music far better remembered than the VIPs. It would be interesting to know how many garage sales you would have to visit to find a player for that 34-year old disc.
Now, the Voyagers are poised at the edge of our solar system, 116 times farther from the sun than our mere 93 million miles. This is the farthest any man-made object has ever traveled, but that distance is not even a nanonanonano-dot in God’s vast universe.
The spacecraft’s power systems should live a few years longer and the girls will continue to talk to us, notwithstanding a 16-hour time delay from transmission to reception. (It’s a long ways out there and light only travels at 186,000 miles per second). When their power systems finally fail, we will not be able to communicate, but obeying Newton’s First Law, (a body in motion or at rest will continue in linear motion or at rest unless acted upon by a force), they will continue traveling at the same speed, forever.
Oh, they might encounter a random star and be burned up, but the stars on the average are about 6 trillion miles apart (a nominal light year), although the nearest star to our sun is over 4 light years distant. One would have to be either very unlucky or a very poor driver to have that happen. In the year 40,272 AD, the Voyagers will careen within 1.7 light years of the star Ophiuchus in the Little Dipper constellation, their first “close encounter.”
There are molecules in space (it’s not a complete vacuum), so the Voyager sisters will slow down a little running into those molecules and exchanging momentum. However, at a rarefied density of only a few molecules per cubic meter, it will be eons before that will be noticed. There is some warmth for those two girls. (They’re only 34-years old and they will live thousands of years, so they could hardly be called women.) It is not absolute zero in outer space. The left-over heat from the Big Bang keeps outer space at about 3 degrees (Kelvin) above absolute zero (thus, -270 OC, -454 OF).
So, smooth sailing and happy 4th of July to the Voyagers from all their friends here the United States of America, the greatest country in the solar system.