The lunar communications relay unit and ground-commanded television assembly operated for 12 hours 44 minutes during the lunar surface extra-vehicular activities. The relay unit in conjunction with the television camera was energized by up-link command for lunar module ascent television coverage and for six days of scientific lunar surface observations on a once-per-day basis until 30 April 1972. At that time, the system could not be energized by up-link command. Down-link data from the relay unit on the preceding day showed the expected temperatures, internal voltages, and RF signal strength. Possible causes of the problem include: (1) malfunction of the television control unit up-link decoder due to its pre-launch predicted high temperature condition (above qualification level), and (2) loss of input power because of incorrect circuit breaker configuration on the lunar roving vehicle that would have placed only one of the two batteries on the line.
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