The secrets of the Galileo spaceprobe鈥檚 final mission remain locked inside its tape recorder, which may have suffered irreparable damaged during a pass through Jupiter鈥檚 intense inner radiation belt.
If the tape cannot be reactivated then the data will be lost forever. The probe is on course to crash into Jupiter in September 2003, but an even more imminent deadline looms. The probe will run out of the propellant needed to keep its antenna pointed towards Earth is 鈥渘early depleted鈥�.
Eilene Theilig, Galileo project manager at NASA鈥檚 Jet Propulsion Laboratory in California, said: 鈥淚t appears that the tape recorder has taken a hit from the intense radiation Galileo passed through. Our efforts to restore the tape recorder may continue for a few weeks.鈥�
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On 5 November, Galileo flew past Jupiter鈥檚 inner moon Amalthea for the first time. It also passed the planet鈥檚 inner gossamer dust ring and entered its high-radiation inner magnetosphere.
Safe mode
The spacecraft鈥檚 instruments were functioning before the probe automatically entered 鈥渟afe mode鈥�, shutting all systems down to reduce any radiation damage. Although the spacecraft itself was reactivated on 15 November, all attempts to switch its tape system back on have proved unsuccessful.
It was initially thought the tape might be stuck, as has happened before. But engineers now believe the recorder鈥檚 electronics may have been wrecked by radiation exposure. Light-emitting diodes or optical transistors in the circuitry may have been affected, NASA says.
Data from Galileo鈥檚 final flyby could provide valuable new insight into the evolution of Jupiter-sized planets and their moons. Galileo has already survived five years longer than originally planned. Prior to its last flyby, it had been exposed to four times the amount of radiation it was designed to withstand.