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.
A variable whose value determines the value of other variables. For example, in the function y = x - 4, x is the independent variable because its value determines the value of y. Noun. 1. independent variable - (statistics) a variable whose values are independent of changes in the values of other variables.