Space Security Index

Space Security 2011
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Figure 1.1: Types of Earth orbits*
* See Annex 2 for a description of each orbit’s attributes.
e total amount of manmade space debris in orbit is growing each year and is concentrated
in the orbits where human activities take place. LEO is the most highly congested area,
especially the Sun-synchronous region. Some debris in LEO will reenter the Earth’s
atmosphere and disintegrate in a relatively short period of time due to atmospheric drag,
but debris in orbits above 600 km will remain a threat for decades and even centuries. ere
have already been a number of collisions between civil, commercial, and military spacecraft
and pieces of space debris. Although a rare occurrence, the reentry of very large debris could
also pose a threat to Earth infrastructure and human lives.
e development of space situational awareness capabilities to track space debris and avoid
collisions, covered in Chapter 2, clearly provides signicant space security advantages.
Eorts to mitigate the production of new debris through compliance with national and
international norms, guidelines, standards, and practices can also have a positive impact on
space security. Technical measures to eciently remove debris, once developed and used,
could have a positive impact in the future.
e distribution of scarce space resources, including the assignment of orbital slots and radio
frequencies to spacefaring nations, has a direct impact on the ability of actors to access and
use space. Growing numbers of space actors, particularly in the communications sector, have
led to more competition and sometimes friction over the use of orbital slots and frequencies,
which have historically been allocated on a rst-come, rst-served basis.
New measures to increase the number of available orbital slots and frequency bands, such as
technology to reduce interference between radio signals, can reduce competition and increase
the availability of these scarce resources. Condence in the sustainability of their use creates
a strong incentive for space actors to cooperate in the coordination, registration, and use of
radio frequencies and orbital slots. Cooperation in this area can also strengthen support for
the application of the rule of law to broader space security issues.
Trend 1.1: Amount of orbital debris continues to increase,
particularly in LEO
e U.S. Space Surveillance Network (SSN) is the system that most comprehensively tracks
and catalogs space debris, although technological factors limit it to spot checking rather than
continuous surveillance, and limit the size of currently cataloged objects to those greater
than 10 cm in LEO and much larger in GEO. Currently, the U.S. Department of Defense
(DOD) is using the SSN to track more than 21,000 objects approximately 10 cm or larger,