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NASA, Space Exploration

30 Years and Still Going Strong

By Joshua S. Hill

Wednesday, August 22, 2007

1977 saw the launch of two of NASA's now venerable space workhorses, Voyager 1 and 2. And more than being a landmark for space exploration, it is a simple reminder of a fact that seems to have been lost to manufacturers of our own age; they built them to last back in the old days.

Launched in reverse, with Voyager 2 launched on August 20 and Voyager 1 launched on September 5 Alan Stern, associate administrator for NASA's Science Mission Directorate describes the Voyager mission as "…a legend in the annals of space exploration."

The first couple of decades saw them undertake detailed scans of Jupiter, Saturn, and their respective moons, before moving on to the first explorations of Uranus and Neptune. Prior to their arrival, these two were unknown worlds, and only visible through our telescopes as something "out there". They revealed the turbulent atmosphere and dozens of interacting hurricane-like storm systems that plague Jupiter's surface, and showed us the waves and icy rings of Saturn.

But it all started out as a four year mission to Jupiter and Saturn, somewhat like Mr. Kirk and Spock. However after the success that Star Trek never showed on its first outing, the Voyager mission was extended to cover a four planet mission, rather than just the two. Upon the completion of that mission though, there was only one direction to go, and for the past 19 years the Voyager mission has been probing the sun's outer heliosphere and its boundaries with interstellar space.

"The Voyager mission has opened up our solar system in a way not possible before the Space Age," said Edward Stone, Voyager project scientist at the California Institute of Technology, Pasadena, Calif. "It revealed our neighbors in the outer solar system and showed us how much there is to learn and how diverse the bodies are that share the solar system with our own planet Earth."

Still going strong at 30 years of age, Voyager 1 is in the process of crossing the final frontier of our little solar system at 9.7 billion miles from the sun, with Voyager 2 at 7.8 billion miles. The heliosphere is where the solar winds slow as they encounter the thin gas that fills space between stars. Any commands sent to the twins take 14 and 12 hours respectively, and with their long-lived radioisotope thermoelectric generators providing power, they're not showing any signs of stopping.

With the New Horizons mission due to reach its destination Pluto sometime in 2015, the Voyager mission is still the premiere deep space exploratory vessels, and will continue to relay data back to earth, as it clocks up some 1 million miles per day.

As the mission continues further away, the Voyager craft are going to encounter, the unknown. Physicists are unsure of exactly what lays at the edge of our solar system, knowing only that the solar rays that ripple outwards will eventually clash with that of another star. At what distance this happens though, they are unsure.

"Does a great dragon, in the form of a cosmic-ray accelerator, lurk within the turbulent boundary of our solar system to breathe out the fire of cosmic rays, or do these rays arise from even more powerful dragons somewhere in deep space?" asks Dr. John Cooper of NASA's Goddard Space Flight Center in Greenbelt, Md

What lays at the edge is what Dr. Cooper is investigating, and with the help of the Voyager vessels he is hoping to confirm or deny his theories. When Voyager 1 reached the termination shock -- the invisible boundary around our solar system -- on December 16, 2004, most space plasma scientists had expected that it would encounter the primary energy source for suprathermal cosmic rays; however nothing was found.

According to Cooper, he suggests that the suprathermal cosmic rays lay further out. "I believe that the suprathermal cosmic rays we see within our solar system instead arise from even more powerful 'dragons' somewhere in interstellar space," he said, continuing the dragon theme. And, with continued reports making their way back from Voyager 1, he says that evidence is beginning to point in his direction.

With Voyager 1 continuing its outward journey, it is up to Voyager 2 to present further details as to whether the termination shock is a point of encounter for these fires of the dragon. "If Voyager 2 also finds no evidence of local cosmic ray acceleration as it crosses the termination shock, it will strengthen the case for more remote dragons in interstellar space, perhaps very far beyond in the galaxy, as the source of suprathermal cosmic rays," Cooper added.

So Happy Birthday to Voyager 1 and 2, and may we continue to hear from you well in to the future!

Other articles by Joshua Hill

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