Voyager 1 Resumes Sending Updates To Earth

quonset writes: Just over two weeks ago, NASA figured out why its Voyager 1 spacecraft stopped sending useful data. They suspected corrupted memory in its flight data system (FDS) was the culprit. Today, for the first time since November, Voyager 1 is sending useful data about its health and the status of its onboard systems back to NASA. How did NASA accomplish this feat of long distance repair? They broke up the code into smaller pieces and redistributed them throughout the memory. From NASA: "... So they devised a plan to divide the affected code into sections and store those sections in different places in the FDS. To make this plan work, they also needed to adjust those code sections to ensure, for example, that they all still function as a whole. Any references to the location of that code in other parts of the FDS memory needed to be updated as well. The team started by singling out the code responsible for packaging the spacecraft's engineering data. They sent it to its new location in the FDS memory on April 18. A radio signal takes about 22 1/2 hours to reach Voyager 1, which is over 15 billion miles (24 billion kilometers) from Earth, and another 22 1/2 hours for a signal to come back to Earth. When the mission flight team heard back from the spacecraft on April 20, they saw that the modification worked: For the first time in five months, they have been able to check the health and status of the spacecraft. During the coming weeks, the team will relocate and adjust the other affected portions of the FDS software. These include the portions that will start returning science data.

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