Published: March 31, 2006
Forty Years of Space Talk
"That's one small step for man. One giant leap for mankind." That famous communique from Apollo 11 during the historic first-ever moon walk was brought to you by the 64-meter antenna at NASA's Deep Space Network in Goldstone, Calif.
The antenna has accumulated a rich legacy during its 40 years of supporting space exploration. In addition to capturing the words of astronauts on all the Apollo moon missions, the dish has communicated with the computers and equipment on every one of NASA's major robotic solar system explorers. The "Big Dish" enabled the world to see the first-ever close-up images of Jupiter, Saturn, Uranus and Neptune, their rings and their myriad moons, by the Pioneer, Voyager, Galileo and Cassini missions. The antenna has also communicated with NASA's Mars missions, including the currently-operating fleet of five: Mars Global Surveyor, Mars Odyssey, the Mars Exploration Rovers and Mars Reconnaissance Orbiter.
The antenna's history stretches back to 1963, when the United States and Russia were engaged in a high-stakes space race. Engineers were relying on smaller antennas to keep tabs on NASA's earliest missions, which ventured only as far as orbit around Earth. With the development of the Mariner Mars missions, more powerful communications tools were needed.
The plan was to build a 64-meter antenna at Goldstone, one of three sites of the Deep Space Network. In 1963, Rohr Corporation was awarded a $12 million contract to design and build the big dish.
After two years of construction, a testing phase began to determine how well the antenna would receive signals. In March 1966, engineers pointed the dish toward Mariner 4, which had been lost by smaller antennas after its historic Mars flyby in 1965. Eureka! Mariner 4 sent a signal, and the Goldstone antenna picked it up.
To commemorate this historic event, the 64-meter antenna was named "Mars," or more technically, Deep Space Station 14. After three months of calibrations and personnel training, the Mars antenna became the first operational 64-meter antenna of the Deep Space Network in June 1966.
The Network includes communications facilities placed about 120 degrees apart around the world - at Goldstone; near Madrid, Spain; and Canberra, Australia. As Earth rotates, this strategic placement permits ground controllers to maintain constant observation of robotic spacecraft exploring the solar system and beyond.
The pioneering Mars antenna was later to expand its repertoire - and its size. In the late 1960s, the antenna was called on to support all the American lunar missions, including Apollo 11, and the nerve-wracking "Houston, we have a problem" Apollo 13 mission. During the critical re-entry of that space capsule, it was more essential then ever for engineers on the ground to maintain contact with the astronauts. The craft's minimal power was needed for re-entry, with little left over for transmitted communications. The antenna was able to capture the "whispers from space," and helped bring the astronauts home safely.
As the years passed, NASA pushed the boundaries of space travel farther and farther. The transmitting capability of the 64-meter antenna was expanded for the Viking Mars landers in the mid-1970s. In 1988, the antenna was enlarged to 70 meters (230 feet) to support the Voyager 2 flyby of the distant planet Neptune.
Today's 70-meter antenna can do much more than track spacecraft. It's also used for solar system radar, imaging nearby planets, asteroids and comets. It does this by transmitting a 500,000-watt signal to "bounce" off the object and return the resulting signal to Earth. Radar allows us to figure out the paths of asteroids and comets and determine whether any might be a possible future threat to earth. The antenna is also used for Very Long Baseline Interferometry, in conjunction with a radio telescope at one of the other Deep Space Network Stations, to precisely measure Earth's orientation. This information helps with spacecraft navigation.
With a fleet of NASA missions already flying and many more planned for the future, the 70-meter Goldstone antenna and the other dishes of the Deep Space Network have a busy lifetime ahead of them.
Source: Jet Propulsion Laboratory
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