Thursday, 12 September 2013, the Voyager 1 spacecraft became the first man-made object to leave the solar system and enter interplanetary space, according to the National Aeronautics and Space Administration (NASA) and the Jet Propulsion Laboratory in Pasadena, California. Voyager 1 was launched 36 years ago this month (5 September), weeks after the 20 August 1977 launch of its twin, Voyager 2.
Exploration has always been about going where no one has gone before.
Voyager’s original mission was to explore the largest gas giants in our solar system, Jupiter and Saturn. Now that it has entered interstellar space, and since it is still able to take measurements and send back signals to Earth, its new mission is the exploration of the environment between our solar system, and the next star closest to earth, Alpha Centauri. It will be able to do so until 2025 unless it collides with something else “out there” before then.
Voyager is traveling at about 17 miles per second. It travels about 4 times the distance from Sun to Earth (four astronomical units) per year. That is close to 400 million miles per year.
The spacecraft was launched in 1977 with technology developed during the 1960s and early 70’s, but exploration is far more reliant on innovation than technology. Technology, is “the branch of knowledge that deals with the creation and use of technical means and their interrelation with life, society, and the environment, drawing upon such subjects as industrial arts, engineering, applied science, and pure science.” Merriam-Webster’s definition is, “the branch of knowledge that deals with the creation and use of technical means and their interrelation with life, society, and the environment, drawing upon such subjects as industrial arts, engineering, applied science, and pure science.”
Technology also draws upon the skills of people around the world like those at Sacramento California’s Aerojet, who made the thrusters on the interstellar spacecraft.
Voyager 2, Voyager 1’s twin, was originally slated to visit Saturn’s planetary system. NASA scientists had wanted to visit all the gas giants: Jupiter, Saturn, Uranus, and Neptune but it would cost too much in resources and hardware to send separate missions to each of those planets with what was available in the early 1970’s.
So, the two Voyagers were built and sent on their projected missions: Voyager 1 just to Jupiter and Voyager 2 just to Saturn. However, a scientist looked into the physics (science) of using Saturn’s gravitation well as a “gravitational sling shot” to build up enough velocity to “shoot” Voyager 2 to Uranus, and again to Neptune, and used similar techniques to get Voyager 1 from Jupiter to Saturn. The science was successfully applied to provide the technical means to allow the spacecraft to visit those planets. That is technology. The same technique was used to propel the Voyagers from the gas giants into interstellar space.
Space is far from empty. There is dust, gas, and objects in space, even interstellar space, but the concentration of matter is sparse relative to the environment people are familiar with.
Going into interstellar space first involves crossing the termination shock “layer.” Voyager 1 passed through this in 2004 and Voyager 2 three years ago. To visualize the termination shock, think of a boat sailing on a lake. That boat builds up a ridge of water in front of it. This ridge is analogous to the termination shock. Another example is the build-up of air in front of a flying aircraft. When the aircraft is able to fly faster than that build-up of air, a sonic boom occurs.
Scientists believe there is a boundary beyond the termination shock wave that separates the solar wind from interstellar wind. This is the heliopause. Determining the heliopause’s exact location and exploring the matter in actual interstellar space is the ultimate mission
NASA calls the new mission the Voyager Interstellar Mission (VIM). The mission objective is “to extend the NASA exploration of the solar system beyond the neighborhood of the outer planets to the outer limits of the Sun's sphere of influence, and possibly beyond….” NASA is using old equipment and modern technology to make new science, because scientists really do not know what is out there.
There is an artifact on each of the Voyagers that hopefully will let people “out there” that there are humans here. The “plaque” (actually a phonograph record) contains graphic images of humans, photos of our world, music, sound recordings, directions on how to play the record, and symbolic representations designed to show where Earth’s location to someone who might find the Voyager.
Since the Voyagers are meant to represent us humans as well as explore the galaxy, ”As the Voyager goes, so go we.”