Voyagers 1 and 2
Twenty-five years of Voyagers 1 and 2
In the late summer of 1977, two identical spacecraft (Voyagers 1 and 2) took off on missions of exploration deep into the outer parts of our solar system. In a departure from an earlier practice, the spacecraft were not given fanciful names from mythology, like Mercury or Gemini or Apollo. They were called simply the Voyagers. Both spacecraft visited Jupiter and Saturn, and Voyager 2 kept going on to Uranus and Neptune. Among many other things, they discovered that Uranian and Neptunian magnetospheres, both of them highly inclined and offset from the planets rotational axes, suggested that their sources are significantly different from other magnetospheres.
The Voyagers found twenty-two new satellites: three at Jupiter, three at Saturn, ten at Uranus, and six at Neptune. Nothing was more surprising than the moon Io, one of Jupiters moons, alive with the most active volcanoes in the solar system, the only solar system body other than the Earth to be so confirmed. Scientists had expected a dead, cratered surface like Earths moon. Triton, a Neptune moon, was found to have active geyser-like structures and an atmosphere. Auroral zones were discovered at Jupiter, Saturn, and Neptune. Jupiter was found to have rings. Saturns rings were found to contain spokes in the B-ring and a braided structure in the F-ring. Two new rings were discovered at Uranus and Neptunes rings, originally thought to be only ring arcs, were found to be complete, albeit composed of fine material. At Neptune, originally thought to be too cold to support such atmospheric disturbances, large-scale storms (notably the Great Dark Spot) were discovered.
Now the wonderous part of the expedition is that both spacecraft are still cruising on, transmitting data far beyond the Suns outermost planets and closer to the true edge of the solar system, where interstellar space begins. The two one-ton spacecraft are pulling away from the Suns gravitational grip and, will just keep going on far into interstellar space. As of March 2012, Voyager 1 was 17.9 billion km away from the Sun, and Voyager 2 was 14.7 billion km away from the Sun. Flight controllers at NASAs Jet Propulsion Laboratory reported that the Voyagers show every sign of being able to function long enough for one more significant discovery: the heliopause, where the solar system ends and the rest of space begins. No one is sure where that is. The heliosphere extends far beyond the orbit of the outermost planet (usually Pluto, but sometimes Neptune) to the farthest reach of the suns magnetic field. In all likelihood, scientists say, the heliospheres boundary fluctuates with the varying strength of the solar wind over the eleven-year cycle of the Suns maximum and minimum atmospheric flux.
The successes of the Voyagers were seen in the volume and clarity of the photography and the steady flow of data on planetary magnetic forces, radiations, and other phenomena. There were the spectacular vistas of the broad pastel bands circling Jupiters atmosphere, like Easter egg decorations, and the bold storm swirls in the style of a Van Gough. Ringed Saturn, beautiful from afar, was even more stunning up close. More thin rings of orbiting debris were discovered and, as hypothesized, tiny moons were found shepherding icy and rocky matter into the rings. Flying by Neptune, the spacecraft revealed the planet to be a pale blue object glowing with auroras and crackling from the radio noise of charged particles trapped by magnetic fields. Icy volcanoes burst through the frozen surfaces of Neptunes moon Triton, to the total surprise of scientists. The Voyagers are expected to survive millions of years of interstellar travel, steadfast as ever; however, they will do it in silence. Their computers and radios will be dead and the Sun will be receding into cosmic insignificance, the two spacecraft will have long since lost touch with their makers and the home on Earth that they left behind in 1977.
Source of Synopsis
Wilford, John Noble. After 25 years, Voyagers seek solar systems end, The New York Times via International Herald Tribune, Wednesday, August 14, 2002, pp. 1 and 5.