NASA’s Communications to Deep Space ‘Fragile’

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 Government Accountability Office found that portions of the 40-year-old system are shut down an average of 16 hours a week for repairs and maintenance.

The GAO report to the House subcommittee on space and aeronautics this week cited three antenna outages in five months last year that resulted in the loss of 241 minutes of scientific data from the Stardust, Deep Impact and three Mars orbiter missions.

Each year, the network communicates with an average of 35 to 40 deep-space missions through 16 giant dish-shaped radio antennas. To provide full coverage of the sky, the antennas are in Goldstone, N.M.; Madrid; and Canberra, Australia.

Mission managers must negotiate with network managers for coverage time, which is limited.

They’re guaranteed 95% of that time for routine and mission-critical communications.

Network officials told GAO investigators they worried about the possibility of failures due to metal fatigue on the aging dishes.

“Ultimately,” the report said, “such a failure would result from a partial or total collapse of an antenna structure.”

No Deep Space Network dish has collapsed yet, but the report points out that an antenna similar in age and design to network antennas -- the 300-foot Green Bank radio telescope in West Virginia -- collapsed unexpectedly in 1988.

Each year since 2002, the study found, NASA has deferred about $30 million in Deep Space Network 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 in antenna facility buildings.

Although the 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 would come from President Bush’s $100-billion Space Exploration Initiative, which is to include increased robotic and manned flights to the moon and Mars.

The GAO noted that NASA was also extending other missions beyond their planned lifetimes.

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.

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 a written response to the GAO, NASA Deputy Administrator Shana Dale acknowledged the “less-than-ideal outcomes” for missions that relied on the aging network. She said the space agency had begun to develop a “road map” to assess the network’s needs and propose upgrades.