They use the atmosphere to help slow the ship down. It takes most of the tank of fuel to get up there and moving so fast. It would take most a tank to slow down. So, they would need about double the fuel plus some for landing.
P.S. I have not done any of the math (I might be able to figure it out but it might take a week or two to figure it out).
P.S.S : Maybe if they could refuel in space efficiently (asteroid mining?) it might be worth looking at but it will be a while before I would expect anything like that. It would just be the ship.
P.S. I have not done any of the math (I might be able to figure it out but it might take a week or two to figure it out).
P.S.S : Maybe if they could refuel in space efficiently (asteroid mining?) it might be worth looking at but it will be a while before I would expect anything like that. It would just be the ship.