A minimum-energy orbit to an outer planet consists of putting a spacecraft on an elliptical trajectory with the departure planet corresponding to the perihelion of the ellipse, or closest point to the Sun, and the arrival planet corresponding to the aphelion of the ellipse, or the farthest point from the Sun.
(a) Use Kepler's third law to determine how long it would take to go from Earth to Mars on such an orbit. (Answer in years.)
(b) Can such an orbit bounder taken at any time? Describe.