Whether it's robotic rovers heading to Mars or, one day, a crew of astronauts, a round-trip journey is an incredibly long one. But there may be a way to find a shortcut. A new study published in the journal Acta Astronautica suggests that hundreds of days could be shaved off a return trip to the Red Planet by using the early orbital data of asteroids. This could bring the total mission time down to as low as 153 days.