Question

What information do you need to calculate the altitude of a satellite’s planet-synchronous orbit? (check all that apply)

Mass of the planet

Radius of the planet

Mass of the satellite

Period of the planet's rotation on axis

Period of the planet's rotation around sun

I said radius of planet and period of the planet's rotation around the sun...What else could it be?

Thanks!

Answer 1

Hey, not around sun!!!
Period of planet spin same as period around planet is what synchronous means so it can stay above the same spot.
That is obvious. I will have to actually do the rest :)

Answer 2

Here is the recipe:
http://www.dummies.com/education/science/physics/how-to-calculate-the-period-and-orbiting-radius-of-a-geosynchronous-satellite/

Answer 3

Thanks! So it's the radius of the planet and the period of rotation on the axis?

Answer 4

Thank you! Just saw the link after I posted the above response, and now I've got it. Browser had some delay...

Answer 5

so
T is planet period (length of day)
Me mass of planet
r radius of orbit
G is universal gravitational constant
r^3 = T^2 G Me /(4 pi^2)
r is from center of planet so we need radius of planet for altitude
altitude = r - planet radius

we do NOT need
mass of satellite (but you surely know that)
or
period around sun (as we discussed)