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Solar System Exploration at 50
Exploration Stories: Favorite Historical Moments

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Twin Rovers
Ashley Stroupe
Robotics Software Engineer / Mars Rover Driver, Jet Propulsion Laboratory
Spirit's Panoramic Camera captured the rover's Instrument Deployment Device above as it moved to get a closer look at an outcrop of rocks named Hillary.
Spirit's Panoramic Camera captured the rover's Instrument Deployment Device above as it moved to get a closer look at an outcrop of rocks named Hillary.

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

I think that the greatest leap forward in scientific discovery and exploration by robots on another planet is the work done by the twin Mars Exploration Rovers (MER), Spirit and Opportunity. Their discoveries have revolutionized our view of the Red Planet by providing ground-scale details of mineralogy and geological processes.

This color view of a mineral vein (likely gypsum, which forms in water) called "Homestake" comes from the panoramic camera (Pancam) on NASA's Mars Exploration Rover Opportunity.

Their greatest discovery to date was finding the first mineralogical evidence of many different water-related processes on Mars, which supported the physical indications of past rivers, lakes and oceans.

The panoramic camera on NASA's Mars Exploration Rover Opportunity produced this approximate true-color mosaic image from a position at the edge of "Endurance Crater."

This is an image of the meteorite that NASA's Mars Exploration Rover Opportunity found and examined in September 2010.

These two rovers together have taught us more about Mars than all the previous missions combined.

This full-circle scene, the Greeley Panorama from Opportunity's most recent winter on Mars, combines 817 separate images to show the view into Endeavour crater and the surrounding terrain. At the far left is Morris Hill, and beyond is Matijevic Hill (Opportunity's current location as of October 2012).

This image mosaic taken by the panoramic camera onboard the Mars Exploration Rover Spirit shows the rover's landing site, the Columbia Memorial Station, at Gusev Crater, Mars.

Though we lost Spirit in 2010, Opportunity is continuing to make scientific discoveries to this day.

Mars crater: Everest.
"This picture is still my favorite of Mars, as it really demonstrates the spirit of exploration." -- Ashley Stroupe

Secondly, the most important first step forward in robotic planetary exploration is the Viking landers on Mars.

This is an image from the Viking 1 Lander of Chryse Planitia.

"This picture, and pictures like it, set my view of Mars and drove me to want to go there." -- Ashley Stroup

Viking 1 landed on Mars on 20 July 1976 and Viking 2 landed on Mars shortly thereafter on 3 September 1976.

Bright Summer Afternoon on the Mars Utopian Planitia
In this image we see Viking 2 looking south. The orange-red surface is strewn with rocks as large as three feet across.

Viking was the first truly robotic spacecraft sent from Earth to another planetary body -- a spacecraft that that was not directly controlled by humans. Viking was also the first autonomous landing on another surface. In this way, Viking set the precedent for -- and proved our capability of -- sending autonomous robotic spacecraft out into the solar system.

Big Joe in the Chryse Planitia
Near the Viking 1 Lander on the Chryse Plains of Mars, "Big Joe" stands a silent vigil. This large dark rock has a topping of reddish fine-grained silt that spills down its sides.

A close third is the Voyager mission, which continues to prove that we can send spacecraft far beyond our reach, and indeed out of our solar system.

Voyager Tour Montage
This montage of images of the planets visited by Voyager 2 was prepared from an assemblage of images taken by the two Voyager spacecraft.

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