At this point Mars is a one way trip, and we have no idea how anyone would live on another planet. You will start hearing much more on Gateway, and the human landing system. The goal is build and staff a base on the moon, learn to live and find ice. They know ice is on the moon, so once you find it you can make fuel. A ship could be built in space, fueled with ice from the moon, and go to Mars. This would also allow you to carry enough fuel to come back. Oh yeah it would be nice to find a way to stop the radiation that will be hammering the people onboard from such a long trip to Mars.