Space Security Index

Space Security 2011
142
example, tests of the Soviet co-orbital ASAT system in the 1960s and 1970s were limited to
two opportunities a day, when the longitude of the interceptor launch site matched that of
the target satellite. is introduced an average delay of six hours between a decision to attack
a satellite in LEO and the launch of an interceptor.
Once an interceptor has been launched toward a satellite, it has committed a signicant
amount of its limited fuel to a specic attack strategy. Evasive maneuvers by the targeted
satellite can force an interceptor to expend valuable fuel and time in reorienting its line
of attack. While such defensive maneuvers require fuel utilization and few satellites carry
extra fuel specically for this purpose, all operational satellites have some fuel allocated to
maintaining their orbital positions, known as “station keeping,” in case of natural orbital
disturbances. ese evasive maneuvers must avoid the weapons eects or target acquisition
range of the interceptor, 33 but the extra fuel required might represent more than 10–20 per
cent of the satellite cost. 34
An interceptor is also vulnerable to deception by decoys deployed from a target. For example,
an interceptor’s radars could be deceived by the release of a cloud of metal foil known as
cha, its thermal sensors could be spoofed by devices imitating the thermal signature of the
satellite, or its sensors could be jammed. 35
Dispersing capabilities, well established in terrestrial conict, can be applied to satellite
operations. 36 Dispersion through the use of a constellation both increases the number of
targets that must be negated to aect a satellite system and increases system survivability.
e U.S. Defense Advanced Research Projects Agency (DARPA) is developing a project
called System F6 (Future, Fast, Flexible, Fractioned, Free-Flying Spacecraft United by
Information Exchange), which seeks to research, develop, and test a satellite architecture
in which the functionality of a single satellite is replaced by a cluster of free-y subsatellites
that wirelessly communicate with each other. 37 Each subsatellite of the system can perform
a separate function or duplicate the function of another module, making the constellation
less vulnerable to electronic or physical interference. In December 2009, a contract valued
at $74.6-million was awarded to Orbital Sciences Corporation for work on the System F6
program, 38 which is expected to become operational in 2013 with an on-orbit demonstration
of a fractioned space architecture. 39
Redundancy in satellite design and operations oers a number of protection advantages.
Since onsite repairs in space are not cost eective, satellites tend to employ redundant
electronic systems to avoid single point failures. Many GEO communications satellites are
also bought in pairs and launched separately into orbit to provide system-level redundancy.
In general, however, there is currently little redundancy of commercial, military, or civilian
space systems, particularly of the space-based components, because of the large per-kilogram
cost of launch.
Greater dependence on space systems is motivating system redundancy. China, the ESA
and the EU, Japan, and India are developing satellite navigation systems that will decrease
dependency on the U.S. GPS. Constellations of satellites such as GPS are inherently
protected by redundancy, since the loss of one satellite might reduce service reliability, but
not destroy the entire system.
Over the longer term, more active measures such as automated on-orbit repair and
servicing capabilities may be able to improve the survivability of space systems. Technology
developments in this area have included the DARPA/NASA Orbital Express program, which
launched two spacecraft in 2007 to test automated approach and docking, fuel transfer, and
component exchange. 40 e three-month, $300-million series of tests achieved a number of