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The 70-meter antenna at the Goldstone Deep Space Communications Complex in the Mohave Desert in California. This complex is one of three comprising NASA's Deep Space Network. Credit: NASA/JPL |
Like the knees of many other middle-aged workers, the joints of the enormous Mars Antenna need replacing. The giant radio dish is a crucial element of NASA's Deep Space Network, and has worked tirelessly at its location in Goldstone, Calif., for over 40 years.
This historic antenna, which measures 230 feet in diameter (70 meters) and communicates with deep space missions, once received Neil Armstrong's famous Apollo 11 message: "That's one small step for man; one giant leap for mankind."
Now, this laborer needs replacement of a portion of its hydrostatic bearing assembly, the system that enables the antenna to rotate horizontally. The repair will be no mean feat: It involves lifting 9 million lbs (4 million kg) of delicate scientific equipment 0.2 inches (5 mm), in order to allow the replacement of the steel runner, walls and supporting grout, which has never been done before.
The $1.25 million upgrade is expected to keep the antenna working for 20 years. The Deep Space Network is managed by NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif.
"This antenna has been a workhorse for NASA/JPL for over 40 years," said Alaudin Bhanji, Deep Space Network project manager at JPL. "It has provided a critical lifeline to dozens of missions, while enabling scientific results that have enriched the hearts and minds of generations. We want it to continue doing so."
The task's scale will limit the speed of repairs, expected to complete in early November. Workers will also replace the elevation bearings, which enable the antenna to track up and down from the horizon. The Deep Space Network will still communicate with space missions by maximizing use of the two other 70-meter antennas at complexes near Madrid, Spain, and Canberra, Australia, and arraying several smaller 34-meter (110-foot) antennas together.
NASA built the Mars Antenna when the first space missions began venturing beyond Earth's orbit. The antenna was the first giant dish designed to receive weak signals and transmit very strong ones far out into space. The antenna featured a 210-foot (64-meter-wide) dish when it became operational in 1966 (later upgraded to 70 meters in 1988 to enable the antenna to track Voyager 2).
Officially named Deep Space Station 14, the antenna picked up the Mars name after its first task: tracking the Mariner 4 spacecraft, lost by smaller antennas after its historic flyby of Mars. The Mars antenna has also supported missions including Pioneer, Cassini and the Mars Exploration Rovers.
The antenna rotating structure, dish and other communications equipment sit on three steel pads above a circular steel runner, oiled by a hydraulic system. After decades of constant use, oil seeped through the runner joints, degrading the structural integrity of the cement-based grout supporting it. Rather than constantly adjusting shims underneath the runner to keep it flat, Deep Space Network managers decided to replace the whole runner assembly.
"The runner replacement task has been in development for close to two years," said JPL's Peter Hames, who maintains the network's antennas. "We've been testing and evaluating modern epoxy grouts, which were unavailable when the antenna was built, updating the design of the runner and designing a replacement process that has to be performed without completely disassembling the antenna."
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