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Solar System Exploration at 50
Exploration Stories: Favorite Historical Moments

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Progression of Knowledge
Dave Doody
Realtime Flight Operations Lead Engineer, Jet Propulsion Laboratory
This gold aluminum cover was designed to protect the Voyager 1 and 2 "Sounds of Earth" gold-plated records from micrometeorite bombardment, but also serves a double purpose in providing the finder a key to playing the record. The explanatory diagram appears on both the inner and outer surfaces of the cover, as the outer diagram will erode over time. Credit: NASA

What do you think are the most significant events that have occurred in the past fifty years of robotic planetary exploration? Why?

Most significant event in the past 50 years? It was the successful creation and launch of the Voyager Mission.

The progression of knowledge through history accelerated when the likes of Tsiolkovsky, Oberth, Hohmann, Goddard, Von Karman, et al, developed the understanding about the key to interplanetary flight being, for the most part, a problem of achieving high velocity, and they mapped out how to do it with real vehicles. Then as the space age dawned, the Jet Propulsion Laboratory (JPL) learned how to do gravity assist in order to tour the solar system -- and right about then learned that the planets were aligning for a 1977 best-launch opportunity that occurs once every 176 years. The Voyagers were then negotiated, planned, approved, built, tested, launched, and navigated to take full advantage of this wonderful opportunity. The Voyagers' enormous scientific successes put JPL securely on the interplanetary map and they continue to push the limits today.

This view (by Voyager 1) is of the region just to the east of the Red Spot and is seen in greatly exaggerated color.

Layers of haze covering Saturn's satellite Titan are seen in this image taken by Voyager 1 on 12 November 1980 at a range of 22,000 km (13,700 miles). The colors are false and are used to show details of the haze that covers Titan.

Jupiter's faint ring system is shown in this color composite as two light orange lines protruding from the left toward Jupiter's limb. The Voyager 2 spacecraft was at a range of 1,450,000 km (900,000 miles) and about two degrees below the plane of the ring when it took this image.

This Voyager 2 high resolution color image, taken two hours before closest approach, provides obvious evidence of vertical relief in Neptune's bright cloud streaks.

Due to Io's volcanic activity, impact craters have disappeared on its surface. This image was taken by the Voyager 1 spacecraft.

We see here Voyager 2's farewell shot of crescent Uranus as it departed on 25 January 1986.

In this view by Voyager, the color variations indicate different chemical compositions in Saturn's rings.

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