- #1

why spacecraft launches are usually terminated at either perigee or apogee?

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- Thread starter jose medina pedraza
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- #1

why spacecraft launches are usually terminated at either perigee or apogee?

- #2

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Who says they are? I'm not even sure what you are talking about as it doesn't seem to make sense.why spacecraft launches are usually terminated at either perigee or apogee?

- #3

davenn

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why spacecraft launches are usually terminated at either perigee or apogee?

As Phinds said ... that didn't make a lot of sense

do you understand what the definitions perigee or apogee are ?

Describe what you think they are and we can work from there

D

- #4

Drakkith

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From here: http://www.braeunig.us/space/orbmech.htm

- #5

Vanadium 50

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Perhaps the OP is referring

I hope this thread doesn't turn into the guessing game "maybe the OP means..."

- #6

http://hyperphysics.phy-astr.gsu.edu/hbase/orbv3.html#ov

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- #8

Drakkith

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- #9

Yep I tried but I don't understand the programming language

- #10

jbriggs444

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The radius of the orbit is not 22,236 miles. Take a trip to Google and look up what reference point that 22,236 figure is measured from.35,786 km (22,236 miles), by knowing that its period is 24 H.

Now, to determine the radius of the orbit from the period, you need to know two formulas:

The centripetal force required to keep a body in circular motion: ##f=\frac{mv^2}{r}## where m is the mass of the object, v is its velocity and r is its distance from the center of the earth.

The force of gravity: ##f=\frac{GmM}{r^2}## where G is Newton's universal gravitational constant, M is the mass of the Earth, m is the mass of the object and r is the distance of the object from the center of the earth.

Solve these two equations for the radius at which gravity is exactly equal to the required centripetal force.

[Hint: the orbital velocity is easily found from the orbital radius and period.]

[Hint: pick a consistent set of units (e.g. meters, kilograms, seconds) and use that]

[Hint: keep everything symbolic until you have a formula for the quantity you are after in terms of things that you know]

- #11

Filip Larsen

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[1] https://en.wikipedia.org/wiki/Orbital_period

[2] https://en.wikipedia.org/wiki/Geostationary_orbit

- #12

Thanks

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