Space Security Index

industry rsts — notably, the rst fully autonomous capturing and servicing of a satellite
without client assistance. 41 e U.S. has also explored other options for more active, direct
protection of satellites such as the DARPA Tiny, Independent, Coordinating Spacecraft
(TICS) program, in which 10-pound satellites could be quickly air launched by ghter jets
to form protective formations, shielding larger satellites from direct attacks. 42 is program,
however, was cancelled in the FY2009 budget. 43
Protection against nuclear attack
Electronics are the foundation of satellite communications networks, and the threat of an
Electromagnetic Pulse (EMP) attack through a nuclear explosion or focused microwaves is
a concern for nations with space assets, as such an attack would involve an “instantaneous,
intense energy eld that can overload or disrupt at a distance numerous electrical systems and
high technology microcircuits, which are especially sensitive to power surges.” 44 Protection
from a High Altitude EMP (HEMP) event involves hardening those electronics that provide
essential services, in conjunction with surge protectors, which may provide an ability to
withstand a HEMP blast. 45 When combined with redundancy of critical components,
however, this type of protection is expensive and not practical for any but the most sensitive
of military satellites.
Early space protection eorts undertaken by the U.S. and the USSR during the Cold War
were aimed at increasing the survivability of strategically important satellites in the face of
nuclear attack. U.S. systems such as the Defense Support Program early warning satellites,
Defense Satellite Communications System communications, and GPS navigation satellites
were all hardened against the radiation and EMP eects of nuclear weapon detonations, as
are all current generation military satellites of advanced space actors. Robust production
lines, the use of satellite constellations, and responsive launch readiness contributed to the
survivability of the USSR’s space capabilities from nuclear attack.
Radiation hardening enables satellites to withstand the eects of nuclear weapons through
the use of radiation-tolerant components and automatic sensors designed to switch o nonessential
circuits during a nuclear detonation. Photovoltaic or solar cells, employed as power
sources in many satellites and particularly vulnerable to radiation eects, can be replaced by
nuclear reactors, thermal-isotopic generators, or fused silica-covered radiation-resistant solar
cell models built with gallium arsenide.
Similarly, EMP shielding protects sensitive satellite components from the voltage surges
generated by the reactions of nuclear detonations with the environment and the internal
voltages and currents generated when X-rays from a nuclear detonation penetrate a satellite. 46
Technical measures to protect satellites from external EMP eects include: 1) metal shields
and conductive coatings to prevent EMP radiation from entering satellite cavities, 2) linking
and grounding of the exterior components of a satellite to create a Faraday cage that will
prevent transmission of EMP radiation to interior components, 3) grounding straps and
surge arresters to maintain surfaces at the same electrical potential, and 4) microwave lters
that isolate internal satellite electronics from external electromagnetic radiation. e use of
graphite composites instead of aluminum construction panels can further reduce the number
of liberated electrons capable of disrupting components. Electro-optic isolators, specialized
diodes, and lters can also be used to shield internal satellite circuits.
Scintillation and blackout measures can be used to avoid the disruption and denial
of communications between satellites and their ground stations caused by nuclear
detonations that generate an enhanced number of charged particles in the Earth’s radiation
belts. Protection against these communications failures can be provided by crosslink
Space Systems Resiliency
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