Aspaceship of mass m has its engines switched off and is moving in a circular orbit at height r above the surface of a planet of mass m and radius r. a) derive an expression for total mechanical energy e of the orbiting spaceship, in terms of g, m, m and r. b) derive an expression for the minimum speed v the spaceship would need to escape from this orbit into deep space, in terms of system parameters. (the engines can’t fire for the whole trip; they can only give the spaceship one boost so it obtains this velocity. ignore all other celestial objects.)