How direction of satellite changes

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Discussion Overview

The discussion centers on how the direction of artificial satellites is altered in outer space from Earth, specifically focusing on the mechanisms of attitude control and the principles behind reaction forces in a vacuum.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant inquires about how satellites change direction and the nature of reaction forces in space without a medium.
  • Another participant explains that orientation changes are achieved through Reaction Control Systems (RCS) or flywheels, relying on conservation of momentum and angular momentum.
  • A different participant challenges a common misconception that rockets require a medium to push against, asserting that rockets operate based on conservation laws and are more efficient in a vacuum.
  • There is a mention of various propulsion technologies, with a preference expressed for mini rockets as a method of attitude control.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of a medium for rocket propulsion, with some emphasizing the conservation principles while others highlight the misconception surrounding rocket mechanics. The discussion remains unresolved regarding the best methods and technologies for satellite direction control.

Contextual Notes

The discussion includes assumptions about the understanding of momentum conservation and the mechanics of rocket propulsion, which may not be universally accepted or fully explored.

lalu
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how the direction of artifical satellites are changing in outer space by controlling from earth? how the reaction force is created at space without any medium .
 
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Hi lalu,

Do you mean changing orientation(aka attitude control)?
It's mostly either by tiny rockets(RCS, or Reaction Control System), which use the principle of conservation of momentum, or by flywheels - a solar-powered electric engine spins a whell in one direction, and the spacecraft rotates in the othe, according to the conservation of angular momentum.

http://en.wikipedia.org/wiki/Reaction_control_system
http://en.wikipedia.org/wiki/Reaction_wheel
http://en.wikipedia.org/wiki/Attitude_control
 
We've had this question arise a number of times here. It springs from a mistaken concept that rockets need something to push against. In this view, rockets launch because the exhaust pushes against the ground and thus forces the rocket to accelerate upward. This is a mistaken concept of how rockets work.

Rockets don't need something to push against. In fact, ground effects make rockets less efficient. Rockets work better when they are far away from the ground, and better yet when they are completely out of the atmosphere.

Rockets work because of conservation of linear momentum and angular momentum. The rocket exhaust going away from the rocket has some amount of linear momentum and angular momentum. The conservation laws dictate that the rocket's linear and angular momentum must change to match whatever is carried away.
 
Bandersnatch said:
Hi lalu,

Do you mean changing orientation(aka attitude control)?
It's mostly either by tiny rockets(RCS, or Reaction Control System), which use the principle of conservation of momentum, or by flywheels - a solar-powered electric engine spins a whell in one direction, and the spacecraft rotates in the othe, according to the conservation of angular momentum.

http://en.wikipedia.org/wiki/Reaction_control_system
http://en.wikipedia.org/wiki/Reaction_wheel
http://en.wikipedia.org/wiki/Attitude_control

I personally prefer mini rokets. Interesting to know. Actually there are lots of propultion techs.
 

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