NASA working on Voyager 2 data problem

[May 07, 2010]  LOS ANGELES (AP) -- Engineers are working to solve a problem with science data transmissions from the Voyager 2 spacecraft near the edge of the solar system, NASA's Jet Propulsion Laboratory said Thursday.

The spacecraft late last month began sending science data 8.6 billion miles to Earth in a changed format that mission managers could not decode.

Engineers have since instructed Voyager 2 to only transmit data on its own health and status while they work on the problem.

That engineering data is in a different format and is fine, said Ed Stone, the Voyager project scientist at the California Institute of Technology in Pasadena.

Launched in 1977, Voyager 2 and its twin, Voyager 1, explored the giant planets Jupiter, Saturn, Uranus and Neptune and kept on going. Nearly 33 years later, they are the most distant human-made objects.

Stone believes the current problem can be solved and does not think it's related to the spacecraft's age, although that won't be known for certain until the diagnosis.

"This is volatile memory just like in your computer where you boot up," Stone said. "And so occasionally a cosmic ray particle can cause one of the bits to flip, or it can actually have a failure in one of the bits."

The fix may be to reset the bit to its proper state or program around it, he said.

It may also be possible to figure out how to decode the data, he said.

The spacecraft transmit around the clock and NASA's Deep Space Network listens about 10 hours a day, Stone said. In normal mode, the transmissions are mostly science data, but at a very low rate of 160 bits per second.

Voyager 1 is 10.5 billion miles from Earth and in about five years is expected to pass through the heliosphere, a bubble the sun creates around the solar system, and enter interstellar space.

Voyager 2 will follow after that.

[Associated Press; By JOHN ANTCZAK]

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