Deorbiting: Possibility and Explanation

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In summary, objects can deorbit other objects they are revolving around through various mechanisms such as interactions with third objects, loss of energy due to gravitational radiation, exchange of angular momentum, and effects of electromagnetic radiation. Having an atmosphere can also contribute to deorbiting, as the object in orbit will eventually slow down and be unable to maintain its orbit. Dark energy and changes in mass, velocity, and orbital energy can also cause deorbiting.
  • #1
deliveryman
Is it possible for an object to deorbit something it's revolving around? Today my Cosmology teacher said that it was possible, and I just want to know how, she didn't give a very good explanation. I always thought because the Conservation of Anguler Momentum it wouldn't be possible. Explaination, anyone?
 
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  • #2
If the 'something' has an atmosphere, no matter how tenuous, it will result in the other something deorbiting, eventually. Just like low-orbit satellites.

If the two aren't totally isolated, interactions with third objects could disrupt the orbit, and may result in a 'deorbit'. Something like this happens to some binary stars in globular clusters.

Left alone for long enough, the system will lose energy due to gravitational radiation, and de-orbiting will result. This is happening with a well-observed pair of neutron stars.

If each object is rotating and not perfectly rigid, angular momentum will be exchanged (think of the tides), and deorbiting may happen, depending on the relative sizes, masses, etc. One day the Moon will deorbit due to this mechanism.

Then there is the Poynting-Robertson Effect and the Yarkovsky Effect. Depending on what EM radiation the two somethings are bathed in, and the smaller something's size (and density, albedo, etc), their rotation rates, etc, etc, deorbiting is possible.

I'm sure there are more ways still; e.g. what about outgassing, e.g. a comet in orbit around Mercury?
 
  • #3
Originally posted by deliveryman
Is it possible for an object to deorbit something it's revolving around? Today my Cosmology teacher said that it was possible, and I just want to know how, she didn't give a very good explanation. I always thought because the Conservation of Anguler Momentum it wouldn't be possible. Explaination, anyone?

Not quite clear on the question. Are you talking about a sattelite deorbitting into its host? That seems to be Nereid's take on things. Or are you asking about a sattelite causing its host to deorbit into something, like the Moon causing the Earth to fall into the Sun?
 
  • #4
Thank's for that reply, though I still have a question

If the 'something' has an atmosphere, no matter how tenuous, it will result in the other something deorbiting, eventually. Just like low-orbit satellites.

How would having an atmosphere cause something to deorbit?
 
  • #5
Originally posted by deliveryman
How would having an atmosphere cause something to deorbit?

For the same reason your hand flys back when you stick it out of a car window.

For something to remain in orbit, it must be going fast... very fast.
If you have an atmosphere, the satellite gets slowed down by flying through it, even if the atmosphere is very thin. That slowing eventually gets large enough that the sat can't stay in orbit any longer.
 
  • #6
Galaxies may deorbit in an outward sense due to dark energy.
 
  • #7
Gravitational Radiation will cause the Earth's Moon for example to slow down eventually to deorbit, because it's converting some of it's orbital kinetic energy into Gravitational Radiation?

Is that the reason why Gravitational Radiation causes a loss in energy with Pulsars and stuff? Please correct me if I'm wrong.
 
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  • #8
deorbiting - - basically, the orbiter either crashes into the orbitee or the orbiter finds a new orbitee. The cause? Changes in mass/velocity/transfer of orbital energy.
 

1. What is deorbiting?

Deorbiting is the process of bringing a spacecraft or satellite out of its orbit and back to Earth's atmosphere. This can be done intentionally to dispose of the spacecraft or to prepare for a controlled landing.

2. How is deorbiting accomplished?

Deorbiting is typically accomplished by firing thrusters on the spacecraft in the opposite direction of its orbit, slowing it down and causing it to fall towards Earth. Some spacecraft may also use atmospheric drag or gravity assists from other celestial bodies to aid in the deorbiting process.

3. Why is deorbiting necessary?

Deorbiting is necessary to prevent the accumulation of space debris in Earth's orbit. If a spacecraft remains in orbit after its mission is complete, it can become a hazard to other spacecraft and can potentially collide with them, causing damage or even complete destruction.

4. Is deorbiting always successful?

Deorbiting is not always successful, as it requires precise calculations and control to bring a spacecraft out of its orbit and back to Earth. Factors such as unexpected changes in atmospheric conditions or malfunctions in the spacecraft's systems can affect the success of a deorbiting maneuver.

5. Can deorbiting be reversed?

Deorbiting can sometimes be reversed if the spacecraft has enough fuel and propulsion systems are still functional. In some cases, it may be possible to re-enter a stable orbit or even extend the spacecraft's mission. However, this is not always possible and depends on the specific circumstances of the spacecraft and its mission.

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