A venerable spacecraft may be nearing a milestone this year.
On September 5, 1977, Voyager 1 was launched atop a Titan IIIE/Centaur rocket from Cape Canaveral, Florida. Voyager made a stunning flyby of the planets Jupiter and Saturn, performing the first close flyby of Saturn’s large moon Titan which ejected it out of the plane of the solar system.
Voyager 1 is currently the most distant object ever dispatched by mankind at over 121 astronomical units (A.U.) from the Sun (1 A.U. equals the mean distance from the Earth to the Sun, just shy of 150 million kilometres.) Voyager 1 is also currently the fastest manmade object moving in respect to the Sun at more than 17 kilometres per second.
Recently, researchers at NASA’s Jet Propulsion Laboratory announced that Voyager 1 may be on the threshold of a crucial milestone; departure from the local solar environment into interstellar space.
According to JPL’s Ed Stone, a 25 per cent increase in cosmic rays hitting the spacecraft was observed from January to June 2012. This could signal that Voyager 1 has reached the heliopause, the outer edge of the heliosphere inside of which the local solar winds prevail. Beyond this boundary, the galactic environment dominates.
This will be the first time a spacecraft has penetrated beyond this bubble around our solar system. To date, five spacecraft are on escape trajectories departing our solar system; Pioneers 10 & 11, Voyager 1 & 2, and New Horizons launched in 2005 set to fly past Pluto in July 2015.
Voyager 1 is moving in the direction of the constellation Ophiuchus. One of the reasons it’s passing the outer heliopause first is that it’s moving forward into our motion around the galaxy, the direction known as the solar apex on the Lyra-Hercules border.
Our solar system moves 16.5 kilometres per second, and takes about 250 million years to complete one revolution about the galactic center. Although Voyager 1 isn’t headed in the direction of any nearby stars, it is carrying the famous Golden Record, a phonograph record with instructions complete with images and sounds from Earth.
The record cover is even coated with an isotope of uranium-238, which may give any discoverers clues to its age by using its radioactive half-life decay. Though intended for the stars, these “messages in a bottle” aboard the Voyager & Pioneer spacecrafts speak volumes about what humanity thinks of itself. These were designed in part by the late planetary scientist Carl Sagan.
Voyager has a plutonium powered generator that continues to drive its 20-watt transmitter. If all goes well, researchers hope to keep monitoring Voyager 1 as it departs the outer environs of the solar system until 2025 as a means to characterize and study interstellar space. That will mean the entire project will have spanned nearly 50 years and generations of researchers.
Voyager 1 is the most distant object tracked by NASA’s Deep Space Network, and has provided a fabulous science return at a modest price. As Voyager 1 departs the tear-dropped shaped bubble around our solar system, it serves as a small note to say that “humanity was here” as it continues to probe the cosmos beyond our solar system.
Read more posts by David Dickinson at AstroGuyz.com.