In May 2012, SOFTBANK MOBILE, Japanese company being engaged in mobile communication services unveiled its provisional wireless relay system using a moored balloon with helium. The balloon used for the system has an approximate size of 7m (diameter) x 4m (height) and an internal capacity of 90 m3, with a gross weight of about 50kg including the mounted devices and mooring ropes.

The balloon having a double structure made of nylon is filled with a little less helium of 80 m3 in order to prevent bursting due to a rise in outside temperature. The development of this system was triggered directly by the experiences of the Great East Japan Earthquake. In order to restore quickly the service area which suffered from communication failures due to the disaster and consequent disturbances, it was the most important aim to provide a system in the shortest possible time, securing a spacious service area and a large communication capacity. In case the current base station is disabled for use due to disasters and disturbances, a balloon mounted with a wireless relay device is launched up to 100 meters high above the ground level, so that a mobile communication service can be made within the zone of 3km radius in the suburban area and 5km radius in the open district.

Junichi Miyagawa, executive managing director and chief technical officer of the company who was taking command to restore the networks on the spot when the Great East Japan Earthquake occurred, said, “We set up a scaffold with an antenna and constructed a temporary base station, but only the neighboring areas could take advantage of the communication service. We could not provide electric waves extensively. Furthermore, most of the tall towers like electric poles fell down and we once thought for real to shin up any climbable trees before getting chewed out by their owners.”

As a result of narrowing a variety of ideas, they came down to the helium balloon for choice ultimately.

Miyagawa added, “After trials and errors we have reached at long last the stage for announcement to the public. It is not quite certain now that this balloon will be helpful as a matter of fact, but we have been tackling this matter in respect of preparedness for emergency. Of course, it is the best not to use the balloon. We wish that other countries of the world as well as Japan will make the most of the balloon for emergency.”

There is a case that hydrogen instead of helium is used as balloon gas for a radiosonde balloon. Regarding the adoption of helium for this system, Teruya Fujii, chief of the Wireless System Research Center of the company said, “Hydrogen has almost two times more floating power than helium does, but the highest priority at this time has been placed upon safety considerations because the balloon is large-sized of 90 m3.”