Systems and methods for long endurance stratospheric operations

An airship system comprising:

• an upper airship;
• a lower airship comprising a replenishable supply of lifting gas for transfer to the upper airship;
• a tether, an upper end of the tether attached to the upper airship and a lower end of the tether attached to the lower airship, in which the airship system is free flying;
• a balloon shuttle configured to accept lifting gas from the replenishable supply while it is mated to a docking fixture associated with the lower airship, travel up the tether to a docking fixture associated with the upper airship, and deliver at least a portion of the lifting gas to the upper airship;
• a logistics airship;
• and
• a payload airship configured to dock to both the lower airship and the logistics airship;
• in which the logistics airship is configured to transport the payload airship to the lower airship and to transfer lifting gas to the replenishable supply.

A method for long term stratospheric airship operations comprising:

• deploying a lower airship connected to an upper airship by a tether, a shuttle running along the tether to deliver lifting gas to the upper airship;
• resupplying lifting gas to the upper airship from the lower airship via the shuttle using a supply of lifting gas stored in a gas reservoir in the lower airship;
• transporting a payload to the lower airship using a logistics tug;
• and
• returning the logistics tug to the ground.

A tethered airship system for long endurance stratospheric operations comprising:

• an upper airship;
• a tether, a first end of the tether attached to the upper airship;
• a lower airship attached to a second end of the tether, and
• a payload airship reversibly mated to the lower airship, said payload airship comprising a payload, said payload operable and operational at an altitude above 18 kilometers;
• in which the tethered airship system is free flying and configured to maintain long duration stationkeeping.