Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Orbital Mechanics help

  1. Nov 2, 2009 #1
    First post here, I'm a student in a BS in Space Studies program and I'm having a little trouble.

    I have

    R vectors = rI rJ rK
    V vectors= vI vJ vK

    ( I'm not putting in numbers to avoid someone doing my homework for me)

    I am having a hard time wraping my brain around getting from that to

    a. What is the specific angular momentum of the satellite?
    b. What is the satellite's inclination?
    c. Calculate the ascending node vector.
    d. What is the spacecraft's right ascension of the ascending node?

    Can someone show me how to figure these out and tell me why?
    I think by biggest problem is that I want to know why I need to plug this number into that spot in the formula.

    Thanks for your help!
  2. jcsd
  3. Nov 2, 2009 #2

    D H

    User Avatar
    Staff Emeritus
    Science Advisor

    Angular momentum is just r×p, where p is the linear momentum vector, p=mv. "Specific" in this case means "divided by mass". Specific angular momentum is thus angular momentum divided by mass, or just r×v.

    As for computing Keplerian orbital elements given a state vector, your textbook is the best bet. The specific angular momentum is key in computing several of those elements. If your textbook is inscrutable, perhaps this wikipedia page and the links on it will help: http://en.wikipedia.org/wiki/Orbital_state_vectors.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook