The Increasing Threat to Satellite Communications

By Sean Patrick Bain
Embry Riddle Aeronautical University

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Modern Security Methods

As in medieval periods, any method developed to combat the threats by those attempting to eliminate or misuse our communications resources will be overcome with time as long as the incentive for superiority remains. The only means to counteract this effect is continuous development of new maneuvers capable of temporarily eluding the threat. The primary methods conceptualized for the near future to combat the threats discussed in this document fall into three primary categories: evasion capability, tactical readiness, and communications beam alteration.

Evasion Capability

Evasion capability describes a spacecraft’s ability to alter its course to avoid any disruption to its operation. This method of avoiding any disturbance to the satellite may seem overly simple and largely ineffective, however it often requires greater coordination than the other two options presented. In general, satellites orbit in a predictable pattern as defined by the mission. It is this predictability that causes the greatest degree of vulnerability to both preventative and misuse attacks. The ability of a spacecraft to alter its course away from a hostile situation would often deter most security breaches. This concept has two major drawbacks, however. Most missions rely on a regular, predictable orbit for timing the communications transmissions and satellite system updates from its’ ground-control station. Although this may be overcome by using more advanced onboard computer systems, this would typically increase the mass of the spacecraft and would limit its payload capability. Additionally, almost all practical computing systems employ digital technology which is very susceptible to space-based interference, any ionic disturbances, radiation, gamma-rays, etc., in which exposure would typically result in a momentary systems malfunction or even destruction. As a result, this solution would require either additional shielding or a computing technology capable of operating in a space environment independent of gravity and a constant link.

The second major problem with the evasion capability lies in the method in which it would change direction. The onboard propulsion system necessary to provide the necessary change in velocity at unforeseen occasions would require an unprecedented amount of propellant relative to conventional Earth-orbiting satellites. Using conventional propulsion systems such as cold-gas, mono- and bi-propellant systems used for attitude adjustment and trajectory changes would require additional room and mass for fuel and exclude the capabilities of any onboard payload. One possible solution to this is the ion-thrusters. Ion-thrusters are regenerative and utilize electricity as a propellant, allowing for a virtually unlimited fuel source when applied to a solar array. These engines have been employed on a number of both space missions since their development, most notably being the Deep Space 1 mission, which served as one of its technology demonstrator. Unfortunately, these systems generate a very low thrust and would not be effective in avoiding a kinetic shell or region of space where the satellite would run the risk of tampering. As technology progresses however, these systems will become more effective and may soon be able to serve the role needed. As the state of technology advances overall, many more alternative propulsion and maneuver-actuating systems will become available to safeguard the user’s interests.

Tactical Readiness

Another concept explored primarily by the military is the possibility of employing an active defensive system. Although this would reduce the payload capability of the spacecraft, assuming the defense system was not the primary payload, it could theoretically provide a virtually instantaneous deterrent from any intercepting spacecraft or hostile ground-station, depending on the defense system applied. With the increasing importance of satellite resources during combat situations as communication relay stations, reconnaissance sources, and even potential weapons platforms, they become an increasingly tempting target for hostile powers. Tactical readiness would provide a satellite with the capability of defending itself from an offensive attack and the possibility of continued operations over an extended period of time despite hostile circumstances. While this system would be most effective in dealing with an offensive attack, the extent of its effectiveness against signal-based attack would lie in the and defense against the source of an intercepting signal and would be ineffective against a passive listening device, such as an illegally-enhanced ‘Privateer’ system described above

The main problem with this concept lies in the political ramifications of militarizing space. Placing weapons in space, either for offensive or defensive purposes, does and will continue to encourage hostile motivation from a potential enemy force, possibly to the extent of inciting the very actions the system would intent to deter.

Communications Beam Alteration

Communications beam alteration is perhaps the most simple and most easily employable solution for avoiding hostile listening stations as well as detection of the satellite itself. This concept would require an adaptable transmitter capable of transmitting high strength signals with a minimal beam-width, as to not provide opportunity for either passive or active data interception systems. A transmission of minimized beam-width would be targeted at a specific receiving station, and avoid any additional communications activity in the interim of its orbit. This narrow beam-width may be accomplished in a number of different ways. One example would be the employment of a steerable parabola antenna, a dish-type antenna designed specifically for high-gain operations and a minimal beam-width, typically 1.6o versus 16o to 20o on typical antenna configurations. Another example would be the use of a focused LASER beam directed at a dedicated receiver. The beams’ amplitude would be varied to convey a digital signal over the distance while providing a minimal coverage area and therefore a minimal opportunity for signal interception.

The primary drawback for this system is that it requires a dedicated attitude assembly for the transmitter antenna or LASER beam projector. This system would be required to coordinate the orbital timing assuming a regular orbit of the spacecraft with that of the ground-based receiver. This operation, although conventionally employed on mission specific spacecraft, is very taxing on the onboard computing power.

The encryption of the data during transfer is another method of altering the beams characteristics. While this has no effect on the physical dimension of the transmit area, it does provide a deterrent against unwanted users employing signal interception equipment. This is also the most inexpensive and most common method employed. The inherent problem with any encrypted message is , unfortunately, that the encryption may be broken by some means and the user may not be aware that the information has become available to unintended users.

Conclusion: The undeniable need for maintaining satellite communication security.

As discussed in this document, it is imperative from the scale of the private citizen to an entire nation, that satellite communications security be considered a priority in the very near future. This applies to everything ranging from private telephone calls to intelligence gathering resources to military reconnaissance equipment. Today, it is becoming easier to utilize satellite technology for means other than its intended use. As the ‘Privateer’ project illustrated above, deliberate and undetectable signal interception is a deceivingly simple task, especially considering the incentives of mercenaries and nations that would seek to profit off of such information. Although there are many ways to combat the emerging problems, they will not continue to be effective for any significant period of time. Technology has progressed to a point in scientific and technological development that users must reconsider the role that satellite communication systems play in lives, and consider methods for protecting strategic interests from those intent on threatening them for personal benefit.