Balky Antenna Could Limit Galileo’s Study of Jupiter

Worried engineers at the Jet Propulsion Laboratory revealed Friday that the 16-foot main antenna on NASA’s $1.5-billion Galileo Jupiter probe may have failed to unfold properly as planned Thursday.

Failure of the umbrella-like 16-foot “high-gain” antenna to open fully would severely limit the speed at which data about Jupiter could be transmitted to Earth and sharply reduce the number of photographs that could be beamed back to the inner solar system.

But JPL project manager William O’Neil said Friday that engineers are optimistic about coaxing the antenna open if, in fact, it did not deploy fully on Thursday as planned.

“The data that we have at this point (do) suggest there has been some degree of deployment, or unfurling,” O’Neil said.

JPL spokesman Frank O’Donnell said late Friday that engineers would delay taking any action to correct the possible problem, at least through the weekend, so they could have “more time to sift through the data.”

The Galileo probe was launched from the space shuttle Atlantis on Oct. 18, 1989. It is scheduled to slip into orbit around Jupiter in 1995 to study the giant planet and its many moons in unprecedented detail, as well as to drop a probe into the giant planet’s atmosphere.

At Jupiter’s great distance from the Earth--the planet is about 500 million miles from the sun--a large radio antenna is needed to achieve the signal strength necessary to transmit high-speed data. The high-gain antenna is capable of transmitting 134,000 bits of data per second, the equivalent of one black-and-white image per minute.

The spacecraft also is equipped with two smaller antennas that transmit at much lower speeds.