QUESTION: A space station orbits the sun at the same distance as the earth but on the opposite side of the sun. A small probe is fired away from the station. What minimum speed (m/s) does the probe need to escape the solar system? MY UNDERSTANDING AND SOLUTION: The escape speed v from a sphere of radius R and mass M is given by the energy-conservation equation as follows: (from "Schaum's 3000 Solved Problems in Physics" book, page 101) (1/2)*m*v^2 = G*M*m / R where; M: mass of the sun (=1.98*10^30 kg) m: mass of the small probe R: Radius of the sun (=6.95*10^8 m) G: Universal Gravitation Constant [=6.67*10^(-11) Nm^2/kg^2] From the equation typed in bold above; v = sqrt(2*G*M / R) and using the numerical values v is found about 616479 m/s . What do you think? Thanks.