Back in the 1970s, how did NASA describe when an event happened during a mission?
For example, when Mariner 10 did its fly-by of Venus, how did the Mariner team refer to that moment in time? Did they use the ordinary date and time from a particular timezone on Earth? Did they count some number of elapsed seconds since the start of the mission?
(Apollo 11, in 1969, appeared to use elapsed days/hours/minutes/seconds from the start of the mission, at least according to transcripts.)