Features

PASADENA — NASA will add a giant dish to the worldwide network of antennas it uses to communicate with interplanetary spacecraft to accommodate an anticipated spike in traffic that threatens to tax the array’s capability. 

The new $30 million dish, to be built beginning this fall outside Madrid, Spain, will bolster the Deep Space Network’s ability to transmit and receive data from far-flung spacecraft. 

Without the 112-foot wide dish, the network faces demand levels that will exceed its capacity by 300 percent during certain periods between November 2003 and February 2004. 

Even with the added tracking power, National Aeronautics and Space Administration scientists say they are going to lose data. 

During the four-month problem period, more than a dozen robotic probes launched by the United States, Europe and Japan are expected to perform critical maneuvers that demand careful monitoring from Earth. Three missions involve spacecraft scheduled to land on Mars, two will enter Martian orbit and two are supposed to make close passes by distant comets. 

“The good news is there are more planetary missions. The bad news is there are more planetary missions to track,” said Ed Weiler, NASA’s associate administrator for space science. “If all these things work, which obviously you have to plan they will, we need more capacity.” 

There are three identical antennas in Goldstone, Calif., and one each in Canberra, Australia, and outside Madrid. 

To further relieve the crunch, the European space agency is building a similar sized dish in Perth, Australia, that it will use to track its Mars Express orbiter and the British Beagle 2 lander, both expected to arrive at the Red Planet in December 2003. 

And the Japanese will press into use a 211-foot dish it built nearly two decades ago to help track its Nozomi spacecraft as it enters orbit around Mars. NASA expects further upgrades will allow it to simultaneously downlink data from any two of the seven spacecraft expected to be operating at Mars during that time. 

“We think we’re going to squeak through here,” said Rich Miller, manager of the office at NASA’s Jet Propulsion Laboratory that oversees planning and commitments for the Deep Space Network. 

Hardware will not be the sole solution to the problem: representatives from various missions will spend until August horsetrading time on the network of antennas in an effort to accommodate the needs of all the various spacecraft. 

“It’s not a good position to be in, because you go in like a gorilla with the other projects and say ’we need this’ and ’we need that,’ then you go back to your own mission and they say, ’You dummy, why did you give that up?”’ said Robert Ryan, operations manager for the Stardust mission, which will fly past the comet Wild-2 in early January 2003. “It’s all a compromise.” 

NASA expects the juggling act will force it to lose some science data that it simply will not be able to downlink from the fleet of spacecraft. That has led to heated exchanges at JPL. 

“It can be stressful. Sometimes temperatures — and tempers — can rise as you are trying to negotiate through a situation,” said Belinda Arroyo, who represents several missions at the bargaining table. 

Even with careful planning, an emergency aboard one or more of the unmanned spacecraft — almost guaranteed, given the number — could further complicate an already difficult situation. 

“That’s going to be the roughest, if there’s a real problem,” said Ryan, of the Stardust mission. 

Looking toward the future, NASA may seek to internationalize the Deep Space Network and enlist more foreign resources in beefing up the global array of dishes. At present, many foreign space agencies rely on NASA support to track their missions. 

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On the Net: Deep Space Network: http://deepspace.jpl.nasa.gov/dsn/