Our skies could soon be home to special airships able to provide local to regional telecommunication services, Earth observation services,
atmospheric science and astronomical observations. The European Space Agency, together with DaimlerChrysler Aerospace of Germany,
Lindstrand Balloons Ltd. of the United Kingdom and the Technical University of Delft in the Netherlands, have completed a first assessment
of a concept for High-Altitude Long-Endurance (HALE) aerostatic craft, positioned in the stratosphere at about 20km altitude – in a region
of space where no aircraft or satellites fly – and with an operational lifetime ranging from months to years.

HALEs are large helium-filled powered airships with an aerodynamic “cigar” shape about 220m in length and 55m in diameter, carrying
payloads of up to 1000kg or so. Unlike Zeppelins, which they closely resemble from the outside, HALEs do not need a rigid overall internal
structure. With modern flexible hull materials, helium-tight and UV-resistant, their design can rely on pressurisation to impart the necessary
stiffness to the airship body. Only local rigid reinforcements for the engine and payload attachment are necessary.

HALEs are equipped with an engine for mobility and stable positioning against stratospheric winds. The altitude of 20km is high enough to
give local or regional coverage of about 100km in diameter and also offers the advantage of minimum wind speeds. Solar cells covering
theupper, sun-oriented parts of the airship skin gather energy at daytime to power a high-efficiency electric engine, which drives a large
propeller, and feed energy into a storage and conversion system, from which it is drawn for nighttime propulsion and operation of the vehicle.

Earth observation is a domain where HALEs can play an important role in permanent or ad-hoc services such as environmental monitoring
or disaster management. After detection of a problem identified via a satellite system, a HALE airship could, after arrival on the scene,
provide detailed, up-to-date and round-the-clock information. These airships could be used – for instance – to guide rescue operations in the
event of a flood or earthquake, when local telephone connections, including ground-net based mobiles, fail and rapid local observations of
the disaster area are vital.

In telecommunications, various applications can be envisaged. Located above a densely populated area, HALE airships could support future
mobile multimedia services (voice, Internet, radio and TV broadcast) without the need for a network of antennas and ground-based relay
stations. Remote meter reading (gas, water and electricity) is another possibility. Quick local observation and information could also make
for more efficient traffic management.

ESA’s interest in HALEs is due to their relevance to a broad range of space technologies such as thin-film solar cells, inflatable technology,
telecommunication equipment, astronomical instruments and various subsystems such as power management and distribution, steerable
antennas, Earth observation sensors and radar imagers. Lightweight design, another typical area of space expertise, is particularly important
to the development of HALE airships. Also Industry is interested: Considerable effort is currently being put into assessing HALE’s business
potential and market access while additional companies and institutions are considering to join the team and discussing their possible roles in
the development and commercial exploitation. This initiative must be seen in the context of similar efforts in Japan (Sky-Net) and the US
(Sky Station Int’l), in which also European Space and Balloon-manufacturing companies are participating.

For further information please contact:
ESA Communication Department
Media Relations – Franco Bonacina
Tel: +33(0) – Fax: +33(0)
ESA/ESTEC – Peter Groepper
Directorate of Industrial Matters and Technology Programmes
Tel: +31(0)71.565.4566 – Fax: +31(0)71.565.5184