Space traffic control readies for travel crunch

The Deep Space Network The Deep Space Network tracking station at Goldstone, California

By Richard Stenger
CNN

(CNN) -- The weary battalion of giant radar dishes that tune in to distant spacecraft should soon have reinforcements, just in time for a long anticipated communications traffic jam in deep space.

The Deep Space Network, a series of radio telescopes in California, Spain and Australia, can listen to almost infinitesimally weak radio signals, as small as a billionth of a trillionth of a watt.

But the super receivers will have their ears full by 2003, when a variety of international probes are scheduled to begin arriving at the Mars system or chasing down comets in the same vicinity of the solar system.

"We're getting ready for a crunch period," said Rich Miller of NASA's Jet Propulsion Laboratory, which manages DSN. "[These new] missions all happen to lie in the same part of the sky."

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Stargazing

The upcoming convoy to Mars includes two U.S. rovers, a Japanese satellite and a European orbiter/lander duo. At the same time, two other NASA probes will make close encounters with comets and another NASA comet mission will have just launched.

The spacecraft will bunch up in one particular sliver of the sky with Mars in the middle.

"We need to track them but we don't have enough antennas," said Joseph Statman, a Deep Space Network engineer at JPL, which is based in Pasadena, California.

Goldstone leads the pack

The DSN consists of three complexes of antennas. The clusters occupy bowl-like areas in mountainous terrain, protecting them from terrestrial radio frequency interference. They are spaced about 120 degrees apart around the world to ensure continuous radio links with space probes.

The Deep Space Network is spread out across the world to ensure continuous radio contact with spacecraft

"No matter where the spacecraft is, you're always in contact with it," said Statman.

The cornerstone of each installation is a 230-foot (70-meter) dish, capable of spotting a probe more than 10 billion miles (16 billion kilometers) from Earth. Smaller, moveable antennas focus near the horizon to track speedier satellites orbiting Earth.

The most powerful of the three, the Goldstone, California, dish can handle more than 400 hours of deep space communications a week, a figure that should rise to 525 hours when a new antenna comes online in 2003.

The one near Madrid, however, can track spacecraft for only about 315 hours a week. A new auxiliary dish should boost the time by 105 hours, according to NASA. As part of the entire network upgrade, engineers will replace older hardware and software with more advanced components and systems.

"Madrid is the most crucial site for an upgrade simply because we need more tracking time there," Statman said.

Moonlighting in the universe

The network discovered that a passing asteroid had a twin

The dish network, the largest and most sensitive scientific telecommunications system in the world, does some impressive work on the side, making astronomical observations throughout the solar system and beyond.

Together, the network clusters combine their power to look inside quasars, some of the most distant known objects in the cosmos. By itself, the Goldstone antenna has done some astronomical sleuthing, making radar images of planets and asteroids.

When one asteroid passed near the Earth last month, astronomers using Goldstone discovered that the space rock was actually two asteroids locked in a tight orbit.