America's space agency, NASA, turns 50 this month. In those five decades, we've leapt from rotary dialing to PDAs, from vinyl 45s to MP3s, and from blurry snapshots of the solar system to detailed images in glorious color. Here we contrast NASA's earliest glimpses with these iconic views, which have transformed our understanding of our place in the universe.
Back when transistor radios were hip, Mariner 4 sent these first close-up views of Mars across 134 million miles using a puny 10-watt radio transmitter. The pictures reached home at an agonizingly slow rate of 8.3 bits per second. Each grainy image took eight hours to receive, but the payoff was huge: Surprising evidence of deep impact craters banished the popular idea of Mars as a chillier version of Earth.
The Mars Reconnaissance Orbiter, sporting the latest in camera and radio technology, is capable of spotting objects only a few feet across. This approximate-color image reveals rippled dunes on the floor of Victoria Crater, whose rim has been scalloped by winds and sandstorms. Within this crater the Opportunity rover--just slightly too small to see here--is studying the landscape up close, finding evidence of ancient, salty waters on Mars.
Almost exactly a year after the Apollo lunar exploration program wound down, and smack-dab in the middle of the Watergate scandal, Pioneer 10 became the first spacecraft to encounter Jupiter, snapping this picture of the giant planet's icy moon, Europa. Pioneer 10 didn't even have a proper camera. Instead, as the spacecraft spun around, a light sensor scanned the face of Europa, building up this picture line by line at a crude resolution of 100 miles per pixel.
In the late 1990s scandal once again surrounded the White House (this time courtesy of Monica Lewinsky), but at least NASA had made progress. The Galileo probe, orbiting Jupiter until 2003, revealed the true face of Europa in astonishing detail. This view is a composite of images taken in 1995 and 1998, color enhanced to show details of the cracks and ridges that stretch across Europa's icy surface. Beneath the ice lies a vast ocean of water that could harbor life. Galileo's camera was able to capture Europa at a resolution of 1.2 miles per pixel.
At a time of economic and political crises on Earth, the Mariner 10 probe raced past Venus on its way to Mercury. In visible light Venus appears covered in a featureless white cloud layer, but a camera onboard Mariner 10 captured these cloud details in the ultraviolet range, which provided clues about the structure of the Venusian atmosphere.
Radar guns were catching speeders back home, but near Venus the Magellan probe was putting radar to more creative ends: using it to map the cloud-shrouded surface of Venus at 300-foot resolution. The simulated colors in this 1991 view are based on pictures of the Venusian surface from Russia's Venera 13 and 14 landers. Brighter colors highlight mountainous regions; darker colors represent relatively smooth areas resulting from lava flows or meteorite impacts.
Technology showed its dark side in March 1979 as the Three Mile Island power plant suffered a severe core meltdown, the nation's most serious commercial nuclear accident. That fall, Pioneer 11, the first craft to approach Saturn, discovered an unusually symmetric magnetic field and took temperature readings suggesting that this cold planet glows with internal heat. The craft also detected two Saturnian moons and a small ring that had never been seen before.
Global warming has replaced the China Syndrome as the number one energy worry in the United States, and Cassini is delivering a whole world of new data on Saturn: rubble-pile moons, record-groove gaps in the planet's famous rings, complex weather systems churning through the pastel cloud cover, and possible explanations for the unrelenting 900-mile-an-hour winds. The still-active Cassini craft also has detected massive electrical storms with thunderheads as big as the entire Earth.