This is referred to in mission planning as Hybrid Local Solar Time (HLST). The time scales are uniform in the sense of mean solar time (they are actually mean time of some longitude), and are not adjusted as the rovers travel. (The rovers have traveled distances that make a few seconds difference to local solar time.)
Answer: An independent variable is exactly what it sounds like. It is a variable that stands alone and isn't changed by the other variables you are trying to measure. For example, someone's age might be an independent variable.
Independent Variable. In regression, the independent variable is the one that is supposed to explain the other; the term is a synonym for explanatory variable.. Usually, one regresses the dependent variable on the independent variable.. There is not always a clear choice of the independent variable.