How does gravity affect rotation?

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    Gravity Rotation
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Discussion Overview

The discussion centers on the effects of a planet's gravitational field on a rocket's rotation during a close flyby, particularly in the context of gravitational slingshot maneuvers. Participants explore the implications of gravitational forces on the rocket's orientation and rotation, with relevance to both theoretical understanding and practical applications in gaming.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how a planet's gravity affects a rocket's rotation during a flyby, noting a lack of familiarity with gravitational effects.
  • Another participant suggests that tidal effects from the planet's gravity could apply a torque on the rocket, potentially changing its rotation rate, but emphasizes that this effect is generally negligible unless the rocket's length is comparable to its distance from the planet.
  • A different participant counters this by asserting that gravity gradient torque is significant in low Earth orbit, providing an example of the Space Station's "torque equilibrium attitude" where gravitational and aerodynamic torques balance each other.
  • A later reply acknowledges the correction and provides a link to a more formal treatment of the problem for further reference.

Areas of Agreement / Disagreement

Participants express differing views on the significance of gravitational effects on rotation, with some arguing that the effects are negligible while others assert that they can be significant in certain conditions. The discussion remains unresolved regarding the extent and conditions under which these effects are relevant.

Contextual Notes

Participants highlight the importance of the rocket's dimensions relative to its distance from the planet when considering gravitational effects, indicating that assumptions about scale and context are critical to the discussion.

Kirl
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I think this is an aproriate forum to ask this, I'm curious to the effect a planets gravity field has on a rocket flying past.

I know it would simply pull in the object harder the closer it gets to it, but does it affect the rotation of the rocket as well? If one slingshots around a planet would the rocket always point the direction it was going in, or would it simply move around the planet in it's original orientation?

I need this info for a game I'm working on, but I found I'm not actually as familliar with gravity as I always thought I was... :wink:
 
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There are small tidal effects caused by the fact that the planet will have a stronger pull on the near side of the rocket than the far side. This can apply a torque and change the rotation rate. However, in most realistic scenarios, this force would be far too small to be noticable. It's only important when the length of the rocket is comparable to its distance to the planet.
 
That is not correct. The gravity gradient torque is a significant effect in low Earth orbit. The Space Station is typically in "torque equilibrium attitude", the spacecraft attitude in which the gravity gradient and aerodynamic torques cancel one another.
 
I stand corrected. Here is a more formal treatment of the problem for the OP:

http://www.aoe.vt.edu/~cdhall/courses/aoe4140/SatDy.pdf"
 
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