I'm totally lost as to where to start with this.. A spacecraft is launched from Earth. The spacecraft goes in an elliptical orbit, with minimum distance to the Sun of 1AU. At the maximum distance from the Sun along its orbit, the spacecraft arrives at Mars, at a distance of 1.5AU from the Sun. Assuming that Mars & Earth both have circular orbits, also ignore gravitational effects of the two planets on the spacecraft. QESTION. The crew stays at Mars after the encounter. They relaunch into the same orbit, at such a time to be back at Earth at the earliest possibility. How long do they stay at Mars & how long is their total journey? I've already worked out that the time to travel to Mars is approx 8.4months, however now i'm at a total loss as to where to go. Any ideas?