PARIS — Thales Alenia Space and Thales signed a contract this week with the DGA, France’s defense procurement agency, to study if intelligence, surveillance and reconnaissance sensors could work from an airship.

The aim of the project is to see if stratospheric platforms of this type, operating from an altitude of 20 kilometers (65,600 feet), where the winds are moderate and the air density sufficient to carry them, could be useful to the French armed forces.

The companies have been asked to design an operational concept study for an ISR mission, including exercises simulating its use in theaters of operation. The contract, whose value was not disclosed, also calls for a full-scale demonstrator to be built capable of flying in the stratosphere to demonstrate how an ISR mission of this type would perform.

Thales Alenia Space (held 67 percent by Thales and 33 percent by Leonardo) launched development of the 100 meters (328 feet) long “Stratobus” airship in April 2016. Powered only by solar energy and measuring 33 meters (108 feet) across, the balloon would rise on its own to its final altitude, with no need for a launcher. To maintain its position and to withstand winds of up to 90 kph (56 mph), Stratobus would have four electric motors operating 24/7, which are controlled by GPS to keep the vehicle permanently in line with a reference point at ground level.

The energy would be broken down into dihydrogen and gaseous oxygen stored separately in tanks placed in the nacelle. At night, the two gases would be recombined, providing water and electricity to power the balloon.

The Stratobus would significantly increase the area monitored by a single platform, as the high altitude puts the horizon at 500 kilometers (310 miles). Considered a hybrid between a drone and a satellite, it would be able to linger for up to a year over a given area after which time it would have to be grounded for maintenance. During these maintenance periods a second airship would ensure mission continuity.

It is expected that each Stratobus would last five years.

Christina Mackenzie was the France correspondent for Defense News.

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