Pasadena : Galileo Antenna Still Shut

Engineers made the Galileo spacecraft spin faster last week, but the maneuver failed to open its main antenna, a problem that will hamper the ship’s $1.4-billion mission to Jupiter, NASA said Thursday.

NASA gave up any real hope of fixing the problem in January after thumping the stuck antenna dish 13,320 times with motors that were designed to open the device. Engineers had said there was almost no chance the jammed antenna would open when they increased Galileo’s spin rate, which had to be done anyway for other reasons.

They were right. When the spin rate was tripled from 3.15 revolutions per minute to 10.5 r.p.m. on Wednesday, the antenna failed to open, said Jim Wilson, a spokesman at the National Aeronautics and Space Administration’s Jet Propulsion Laboratory.

The antenna was designed to unfold into a 16-foot-wide dish that looks like an upside-down umbrella with 18 ribs. Engineers think that three of the ribs are stuck to a central tower.

Galileo must depend on a much smaller antenna dish to transmit data from Jupiter from 1995 to 1997. NASA has said it expects to accomplish 70% of the mission’s scientific goals, although Galileo will return only 2,000 to 4,000 pictures instead of the planned 50,000.