The U.S. space agency NASA has been probing the solar system with an increasingly sophisticated contingent of orbiting telescopes, satellites, and spacecraft throughout its 50 year history VOA's Paul Sisco looks at some of the unmanned probes NASA has developed to explore and learn about the universe in part two of his look at NASA's first five decades.
For half a century NASA has explored the universe - its satellites collecting data and images of our solar system and deep space.
The Hubble Space Telescope, Cassini space probe, Voyager and Phoenix spacecrafts are just a few of the hundreds of NASA probes that have ignited the public's enthusiasm. Each has played an important role in expanding our knowledge of distant worlds and the outer edges of the universe.
"The very first thing we sent was the Ranger (space probe)," NASA curator and scientist David Williams said. "They shot it straight towards the moon, it started clicking its cameras and it just went in clicking its cameras and boom, smashed on the surface."
Later probes landed on the moon and photographed it from orbit, paving the way for the manned Apollo landings.
"Still some of the best photographs we have of the moon are from those lunar orbiters in the sixties," Williams said. "So these spacecraft characterized the moon so completely that when we sent people there we knew what to expect. And I think that's what that's part of what we're doing for Mars now sending all sorts of probes to different parts of Mars, looking at everything we can see and try to figure out the best place to go."
A number of probes have mapped, photographed, landed and even driven on Mars, providing spectacular panoramas of the red planet, evidence of water, and more.
The Phoenix lander, there now, is taking pictures, analyzing the soil and the atmosphere.
NASA has, in fact, launched probes to every planet in the solar system. Perhaps none more impressive than the Voyager probes - launched in 1977, built to last five years, they just keep going.
Space historian Richard Launius is with the Smithsonian's National Air and Space Museum, said that "Voyager is out there its beyond the point at which the solar system has real hold on it any longer from a gravitational perspective."
After making observations of Jupiter, Saturn and their larger moons, the two Voyager probes went on to Uranus and Neptune.
"We discovered world after world that had each been points of light and each of them was distinct and different," said NASA project scientist Ed Stone. "As a scientist it was just an incredible period of discovery and even today we're still discovering things that we hadn't thought of before."
The Voyagers provided details of Saturn's rings and discovered winds blow up to two thousand kilometers per hour on Neptune.
Finally, it is the Hubble Space Telescope that has captured the public's attention like no other NASA probe.
Launched in 1990, the so-called, "window on the universe," has produced hundreds of thousands of spectacular images expanding scientists' knowledge of deep space.
Shuttle astronauts will soon return to the space telescope to improve its imaging capabilities, allowing it to continue to probe deep into the mysteries of the universe.