> do the math mass of a recent space x starship: 5x10^6 kg estimated mass of the earth: 6x10^24 kg estimated mass of the sun: 2x10^30 kg just doing a rough calc, the mass relation of a rocket to the earth is somewhere in the range of 10^-15. so about > 0.000000000000001 % meanwhile the mass relation to the sun is 10^-24, so about > 0.000000000000000000000001% so while what you're saying is true in principle, the actual scale does matter. once we to get to the point where we're moving around so much matter on an interplanetary scale that we start hitting closer to say, 0.0001% of earth mass, we can begin to worry about the reprecussions of universal gravity attraction. until then, we should worry more about actually getting back to the moon, or mars, or wherever we want to go at all in the first place. i'll add that, if you want to go the full mile and factor in the 10^-11 of the gravitational constant, it looks closer at first glance, but then you gotta factor in the distances (r^2) involved as well, and even just the (~400000km)^2 gives you another 10^12 on the underside of the fraction so you're basically back to ballpark of the mass pure relations again.
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