PREVIEW FOR LATER TONIGHT: Bob Zimmerman reports that a standard three-week communication blackout with Mars has begun due to the sun blocking the line of sight between Earth and the Red Planet. While relay satellites may eventually prevent these biannual

PREVIEW FOR LATER TONIGHT: Bob Zimmerman reports that a standard three-week communication blackout with Mars has begun due to the sun blocking the line of sight between Earth and the Red Planet. While relay satellites may eventually prevent these biannual interruptions, NASA currently prepares all spacecraft to withstand the temporary silence.
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