Thu, Oct 25, 2012 - Page 9 News List

Voyagers carry on legacy of the human race

Thirty-five years after leaving Earth, Voyagers 1 and 2 have reached the very edge of the solar system. The two antiquated probes are likely to outlive us, and perhaps even the Earth itself; the only record of our existence, circling the galaxy forever

By Dallas Campbell and Christopher Riley  /  The Guardian

With these signatures and their golden records on board, the twin spacecraft were launched in late summer of 1977 from Cape Canaveral, Florida, and placed on a “grand tour” trajectory that would carry them on fleeting, but historic, fly-bys of Jupiter and its moons, and then on to Saturn and its rings. Deflected towards Saturn’s moon Titan, Voyager 1 would head out of the plane of the solar system and off in the direction of the northern constellation of Camelopardalis.

Voyager 2 would carry on towards an encounter with Uranus in 1986 and Neptune in 1989, which would accelerate it to more than 80,470kph and hurl it in the direction of the brightest star in our sky, Sirius.

On the course of this journey past the giant planets, the craft returned more than 67,000 photographs to Earth — among them stunning images of worlds we had not even dreamt of.

As Voyager chief scientist Ed Stone put it as they flew past Saturn: “Our imaginations were not nearly up to what nature provided.”

The pictures have challenged our understanding of meteorology and geology — redefining our understanding of the solar system and of planetary science as a discipline.

These were places that we had only known as fuzzy pinpricks of light seen through telescopes from Earth before Voyager. These two spacecraft on the grandest of grand tours have taught us more about the outer solar system in the last 35 years than in all of human history. It was, and still is, mankind’s greatest voyage of discovery. However, it is perhaps appropriate that the final image captured by Voyager, the image for which the mission is best remembered, was of ourselves.

On Valentine’s Day 1990 Voyager 1 was instructed to turn its cameras around to snap a final family portrait of as many of the planets as possible, seen uniquely from 6 billion kilometers above the solar system. The imaging team knew that, from this distance, each planet would occupy less than a pixel.

It would be the farthest picture ever taken of home, capturing us as a single speck — an almost invisible point in the black ocean of space. When the photograph was first printed, Earth was mistaken as a speck of dust which Voyager scientists initially tried to brush off the glossy print. Yet this visually underwhelming image of Earth — a “pale blue dot” as Sagan described it — was as profound as the spectacular whole Earth images captured by the Apollo astronauts about 20 years before.

Not long after taking this final picture, Voyager 1 passed the orbit of Pluto, and by the end of 2004 had entered the realm of the Kuiper Belt — a band of dark, Pluto-like worlds of rock and ice orbiting the Sun, almost imperceptibly far away. Voyager 2 reached this domain shortly afterward. Today the two spacecraft still continue to hurtle away from us at 16km per second.

Thirty-five years after leaving Earth, and now 18 billion kilometers from home, Voyager 1 is entering the “bow shock” — a region of space marking the boundary between the solar and the galactic winds — the edge of the Sun’s influence. Voyager 2 has also encountered this frontier, as each craft prepares to enter the region astronomers call “interstellar space.”

Five instruments on each craft are still functioning, reporting back the nature of this new environment into which we have extended our senses; characterizing the new magnetic fields and galactic particles they are now in contact with.

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