High Altitude Platform Systems (HAPS) and Unmanned Aerial Vehicles (UAV) as an Alternative to Small Satellites

Abstract

The advantages of a high altitude to provide telecommunications, broadcasting, surveillance, remote sensing, and military related services have been known for a long time. For many years the options have largely been limited to ground-based antennas on towers or mounted on top of buildings or mountains or satellite systems. Other options such as balloons, aerostats, or other alternatives such as kites have all largely proved to be unreliable. Such systems have not proven reliable in maintaining power and altitude, especially in violent rain and wind storms.

In recent years the idea of an intermediate altitude option to ground based towers or satellites has been re-explored in the form of what have been formally designated by the International Telecommunication Union (ITU) as High Altitude Platform Systems (HAPS). The ITU designated service for radio communications from HAPS has been specified to operate in the altitudes of 20–50 km. The practical uses of the altitudes known as near space or as the “Protozone or “Protospace” (i.e., the stratospheric region from 20 km to 160 km) have in recent years grown from essentially nil to a wide range of new applications.

This range of altitudes, sometimes described as near space, the “Protozone” or “Protospace,” is usually referred to as the area above commercial airspace and most military aviation (i.e., 20 km) and below the altitude where one can sustain a satellite in orbit for a long periods (i.e., 160 km). This area has slowly but steadily emerged as an area of interest for many new and innovative uses. These applications of the Protozone include high altitude platform systems (HAPS), dark sky stations, possible use by robotic air freighters, hypersonic missiles, and hypersonic craft performing so-called “space tourism” or even hypersonic transportation systems.

The uses of a reliable high altitude platform system that could maintain a relatively stable platform for a sustained period of time might be used for telecommunications and networking, broadcasting services, stratospheric atmospheric research, remote sensing, surveillance, and other military uses.

This chapter discusses the various efforts that have been undertaken to develop HAPS technologies and systems as well as the various practical, military, and research applications that have been envisioned for so-called “near space” or “protospace” or “the Protozone.” A range of different technical approaches have been proposed and tested. These have included flown platforms using both pilots and automated systems (i.e., balloons, airships, dirigibles, and zeppelins, and even powered kites), platforms that are jet powered, platforms that are solar powered and automated, and even platforms that use microwaves transmitted from the ground and converted to electrical power to power such stratospheric platforms for a sustained period of time at a stable altitude and position. Several initiatives have been seriously pursued, and space research organizations such as NASA and JAXA have carried out serious experimental projects in this area. Also some aerospace companies are prepared to offer commercial HAPS capabilities to carry out a number of difference “Protozone-based services.”

Such high altitude platform systems (HAPS) are seeking to prove that they can be reliable in service, stabile in their altitude and positions, have adequate power, and be cost competitive with low Earth orbit satellite services. Today billions of dollars are being spent on deploying large scale satellite constellations using small satellites. The question is whether HAPS-based networks can offer viable competitive service? This chapter seeks to provide useful information that might help to answer that question.