Ziad I. Akir

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Introduction

Space communication has become an integral component of our overall global telecommunication infrastructure. Satellites are being used for telecommunication, business, entertainment, education, Internet, navigation, remote sensing, imaging, and weather forecasting.

Satellites are also providing backup communication capabilities when terrestrial communication is interrupted in cases such as earthquakes or other natural (or unnatural) disasters. The September 11th events in 2001 demonstrated the value of redundant satellite systems in supporting rescue efforts.[1]

Many governments, including the United States government, rely on commercial satellite systems for communication, commerce, and defense. Commercial satellite systems include ground-based components such as earth station antennas, data terminals, and mobile terminals; and space-based components include satellites and other systems (e.g. space station and launching vehicles) now essential to global function.

Commercial sectors and governments around the globe have huge investments in space ranging from GEO and LEO satellites to the International Space Station (ISS) currently being constructed. These assets are being used to support essential operations such as banking, telecommunication, imaging, manufacturing, and research as well as military applications. Moreover, satellites provide services that contemporary human life and well being have come to depend on such as predicting natural disasters, guiding ships and aircraft, providing distance education, and telemedicine.

Satellite systems are nevertheless subjected to intentional as well as unintentional threats. These threats may be ground-based, space-based, or interference-based. Threats may appear in the form of natural disasters on earth that can hit terrestrial stations and cause service disruption due to damage or power outage. Environmental threats in space can be due to solar/cosmic radiation or space objects including debris. Solar activity as well as human activities may cause signal interference and jamming of service.

This paper is about security of space systems. My objective is to identify the various vulnerabilities and threats to such systems in space, namely communication satellites, International Space Station, and space transport (e.g. Space Shuttle), as well as supporting systems on the ground. Once the issues and threats are identified and explained, the paper will address the various commercial, social, and political consequences of space systems vulnerability. The paper also presents some potential solutions to the various threats to space systems.

Understanding Space Security

Commercial satellite systems are becoming more and more vulnerable to direct physical attack, cyber invasion, and various forms of interference. The mechanical failure of PANAMSAT's Galaxy IV satellite in 1998 disabled around 90% of the paging network in the United States for two to four days.[2]

In orbit, satellites face threats from "space junk" floating about and from bad weather on earth. A storm may discharge electrical currents that hit power grids and short out transformers and other electrical systems that operate earth stations and satellite control systems.[3]

A listing of natural threats to commercial satellite systems is noted in Table 1.

Natural disasters such as earthquakes, floods, thunderstorms, lightning, dust storms, heavy snow, tropical storms, and tornadoes may damage or destroy ground stations. Ground stations may also be affected by air pollution and harsh temperature environments, as well as power failure.

Type of Threat	Vulnerable Satellite System Component
Ground-based: Natural Occurrences (including earthquakes and floods; adverse temperature environments) Power Outage	Ground stations; control centers and data links
Space-based: Space Environment (solar, cosmic radiation; temperature variation) Space Objects (including debris)	Satellites; control centers and data links
Interference-based: Solar Activity; atmospheric and solar disturbances Unintentional Human Interference (caused by terrestrial and space-based wireless systems)	Satellites; control centers and data links

Satellites in space are vulnerable to space-based environmental changes such as solar and cosmic radiation, solar disturbances, temperature variations, and natural objects (meteoroids and asteroids). The growing number of satellites in space adds to the problem of space "junk" in the form of spacecraft and debris[4] which increases the probability of collisions in space.[5]

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