Before 1962, most of the planets in our solar system were hardly more than blurry dots in some astronomer’s telescope.
The most the scientists knew about Mercury, Venus, or Jupiter was their size, surface temperature, and atmospheric composition. But on Dec. 14 of that year, the Mariner 2 spacecraft flew by Venus. For the first time, researchers had detailed and up-close information about other worlds, helping spawn new fields such as astrogeology and modern planetary science. The planets in our solar system changed from distant points to fully-fledged worlds, with distinctive and amazing features.
Image: A roll of data from Venus from the 1962 Mariner 2 mission. NASA
A recent issue of Eos, the weekly magazine published by the American Geophysical Union, praised the last 50 years of solar system exploration in a special feature. The article highlighted how much knowledge scientists have gained in the half-century since Mariner 2’s flight and reminded readers of the unique time we are living in.
“As Carl Sagan used to say, only one generation of humankind can be the first explorers of the solar system, and we are that generation,” wrote astrogeologist Michael Carr from the U.S. Geological Survey (USGS) in the feature.
Here we take a look at just one small sliver from the wealth of information that has come to us from five decades of robotic spaceflight. In this gallery, we can see how our knowledge has grown in leaps and bounds during the last 50 years by looking at some of the biggest, most impressive, and all around greatest geologic structures in the solar system.
Above:
What Makes Up the Moon
In 1992, the Jupiter-bound Galileo spacecraft made a pass by our planet’s closest companion, the moon. This mosaic shows the different composition of rocks left behind by lava flows early in the moon’s history.
Image: NASA/JPL