Does the necessary delta v given to a satellite (earth orbiting) by the rocket during its launch depend on the positions of other planets? Please justify your answer.

  • 3
    $\begingroup$ More clarification is needed here... are you only referring to interplanetary probes, or any satellite, including Earth-orbiting? If it's the latter, then the answer is simply no. $\endgroup$
    – user29
    Aug 14 '13 at 15:36
  • 4
    $\begingroup$ If you consider lunar and jovian perturbations, the short answer is yes. However, the scale of those perturbations is much less than uncertainty in rocket performance. $\endgroup$ Aug 14 '13 at 15:39
  • $\begingroup$ The answer is strictly yes, but practically no per @PearsonArtPhoto 's response. $\endgroup$
    – Erik
    Aug 14 '13 at 23:48
  • $\begingroup$ If you're sending to other than just Earth orbit, the position of the target bodie(s) (Moon, other planets) would determine the launch window, in order to minimize the boost (speed) needed to get there, or conversely, allow for a larger payload. Launching outside the window requires more fuel burn (for course corrections). This has very very little to do with gravitational effects at launch, as discussed in other answers. "Please justify your answer" -- is this homework? $\endgroup$
    – Phil Perry
    Jul 11 '14 at 17:04

Not really. Here's the effect that a few major bodies would have, depending on the direction launched, expressed in the unit of Newtons/kg. Note that 9.8 N/kg is the equivalent of Earth's gravity. I used this calculator, and this table.

Sun       0.00593
Moon      5.554E-9
Jupiter   1.352E-7 to 3.664E-7

Bottom line, it might be beneficial to launch at noon, but there won't be much of a difference really no matter what you do. These are extremely small, and really just don't make much of a difference. 0.1% of the Earth's gravity at the surface is negligible. Put another way, Earth's gravity at sea level is about 9.8201024640745, 1km higher is 9.8170204389969, for a difference of 0.0030820250776. That's about half of the effect of the sun, a very small effect indeed.

The requirements change considerably if you plan on leaving Earth Orbit, but I won't get too much in to that complexity.


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