# Homework Help: Satellite prediction

1. Sep 16, 2008

### jstrz13phys

I am completely lost. I am taking a course in Space Engineering. I have been asked to predict (without a program/software) when I will be able to see a satelite from a given lat, long from earth. I know the altitude is 350KM and I also know the inclination angle to the equator. It is in a circular orbit so I know what the average speed is. What I dont know is where to go next. Everytime I start I get lost - how do I handle spinnig earth, the woble the earth has from moon, etc.

2. Sep 16, 2008

### mgb_phys

First law of physics, if in doubt - draw a picture!
Assume you are on the equator (just for starters) draw the circle surface of the earth and then a parralel circle orbit 350km away.
Draw a straight line at a tangent to where you are standing on the earth, this is the horizon, you can see the satelite once it is above this line.
Knowing the radius of the earth and drawing a couple of triangles should give you the angle betwen the satelite rising and setting, since there are 24 hours in a full circle this gives you length of time you can see it from where you are standing.
Obviosuly with no other data you can only give a relative answer in terms of X mins before and after it is overhead.

Beyond that you are going to have to hit the dreaded spherical trig books !