Review finds aging NASA antennae

Network for space probes often shut down for repairs


The aging global antenna network that keeps NASA in touch with its most distant space probes is fragile and may not be able to meet rising demands for its services, according to a government report.

A review of NASA's Deep Space Network by the General Accounting Office found that portions of the 40-year-old system are shut down 16 hours a week for repairs and maintenance, on average.

The GAO report to the House Subcommittee on Space and Aeronautics cited three antenna outages in just five months last year that resulted in the loss of 241 minutes of science data from the Stardust, Deep Impact and three Mars orbiter missions.

FOR THE RECORD - A story about NASA's Deep Space Network in yesterday's Health and Science section incorrectly listed the location of one part of the antenna system. The Goldstone complex is on the Fort Irwin Military Reservation, northeast of Barstow, Calif.
The Sun regrets the error.

Each year, the DSN network communicates with 35 to 40 distant spacecraft through 16 giant, dish-shaped radio antennae. The antennae are located in Goldstone, N.M., Madrid, Spain, and Canberra, Australia, to provide coverage of the entire sky.

Mission managers must negotiate with the network for the limited coverage time available. They're then guaranteed 95 percent of that time for routine and mission-critical communications.

DSN officials told GAO investigators they worry about failures due to metal fatigue on the aging dishes. "Ultimately, such a failure would result from the partial or total collapse of an antenna structure," the report said.

None of the DSN's big dishes has collapsed yet, but the report cites, as a warning, the 1988 collapse of the 300-foot Green Bank radio telescope in West Virginia. It was similar in age and design to the DSN antennae and has since been replaced by the 328-foot, $74.5 million Robert C. Byrd Green Bank Telescope.

Each year since 2002, the study found, NASA has deferred about $30 million in DSN maintenance projects, forcing managers to reallocate scarce resources to the most pressing maintenance issues. The rest go wanting. The report includes photographs of corroded antenna structures, eroded access roads and water-stained walls inside antenna facility buildings.

Although the Deep Space Network has been able to meet most of its responsibilities so far, the GAO report said, the infrastructure "is aging and is likely to become increasingly fragile and subject to breakdown at a time when demand is anticipated to increase. The potential exists for the loss of scientific data that would be difficult, if not impossible, to replace."

Some of the new demand will come from President Bush's $100 billion Space Exploration Initiative, which will include increased robotic and manned flights to the moon and Mars.

At the same time, the GAO noted that NASA is extending other missions beyond their planned lifetime. These include the Mars rovers Spirit and Opportunity, the Cassini mission to Saturn, and the Voyager missions, launched in 1977 and still exploring the edges of the solar system.

"Capacity limits constrain the amount of science data that can be returned from deep space by new missions," the report said.

The GAO report, like a National Research Council report three years ago, calls on NASA to more effectively manage the communications needs of its scientific missions.

In written response to the GAO, Shana Dale, an assistant NASA administrator, acknowledged the "less-than-ideal outcomes" for missions that rely on the aging network. She said the space agency has begun to develop a "roadmap" to assess DSN's present and future needs and propose upgrades.

Although NASA missions using the DSN continue to meet their goals, she said, "NASA shares GAO's concerns about the future capacity and capabilities of the system."

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