 So the problem is you've got to be lined up properly. It happens every two years to leave from Earth to get to Mars. And then you have this window that you can use to come back with the minimum amount of fuel and energy needed. So it'll be one of those two. It seems to most observers that the year-long stay makes more sense because you can get a lot more done. But there are others that support the month-long stay because it's less risky and it takes less life support.