nasa considering fuel depots in the skies

from nytimes: By considering a proposal to put filling stations in the sky, NASA is looking to accelerate plans to send astronauts to distant destinations. The filling stations — NASA calls them propellant depots — would refuel a spacecraft in orbit before it headed out to the moon, an asteroid or eventually Mars. Currently, all of the fuel needed for a mission is carried up with the rocket, and the weight of the fuel limits the size of the spacecraft.