The relativistic "time factor" is a function of (1 - v^2/c^2).

A "back of the envelope calculation gives a relativistic "time factor" of approximately 2 parts in a billion between Earth and Mars. Your watch would gain about 1 second every 15 years. Not exactly worrisome. Besides, the GR effects of the differences in gravitational potential would probably swamp the SR effects for velocity differences.

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson