1. The problem statement, all variables and given/known data In a science fiction story, humans have built a large spherical spaceship for an interstellar journey of many generations; they have christened their ship Big Bird. The mass of Big Bird is 7.496×1011 kg (the mass of an aircraft carrier is about 10^8 kg). Most of Big Bird's journey takes place at constant speed through the vacuum of interstellar space. Big Bird is accompanied on its journey by a small satellite which is held in orbit about Big Bird solely by Big Bird's gravitational attraction. The satellite is called Little Bird and has a mass of 1000 kg. Little Bird is in an elliptical orbit about Big Bird; the distance of closest approach is 5 km and the greatest separation distance is 40 km. Find the difference in total mechanical energy for the system; i.e. mechanical energy at maximum separation minus mechanical energy at closest approach. 2. Relevant equations E = K + U K = 1/2mv2 U = -Gmm/r 3. The attempt at a solution I am a little confused on this problem. i only seem to know the equation for V for a circular orbit so i am not sure how to go about this problem. would i maybe do this mL = mass of little bird and mB = mass of big bird 1/2mLv2 + -GmBmL / r1 - [1/2mv2 + -GmBmL / r2 ] r1 = 40,000 m r2 = 5,000 m Thanks for any suggestions on what to do cause i am completely lost on how to go about this problem.