Aerospace and Electronic Systems Magazine January 2018 - 19

Hussein, Silva-Martinez, and Wilson
In active illumination, a laser array sweeps the area of the sky
being scanned, and the same array is pointed back at the expected
time of return of the signal in a detection mode. This technique
provides many advantages over passive observation, namely precise distance measurement, surface characterization and independence from the object's reflectivity. Lasers in or near the optical
spectrum can be used for active searches of the sky. They provide
a more focused energy beam and reduce the power requirements
for operation. While only a laser array greater than 1 km in diameter could be used for active detection in significant areas of the
sky, the smaller versions can be extremely useful tracking tools
for small asteroids and can scan small sky patches currently out of
range of optical telescopes, such as regions near the Sun [31]. The
fly-eye telescope and other wide field-of-view telescopes can allow for observation of the entire sky once a day to search for NEOs
and long-period comets (LPCs). Two of these telescopes, one for
each hemisphere, and two dedicated follow-up telescopes distributed properly can detect 90% of the objects down to 160 m in size
in the first two to three decades of observation, and up to 50% of
the objects down to 20 m diameter in the first decade [32]. Laser communications can reach data download rates to the Earth of
about 0.6 Gbps at distances as far as the Moon [33]. Telescopes in
orbits far from the Earth are currently constrained by the data rates
achieved with radio communications, so achieving high download
rates is an enabling technology for cosmic threat monitoring from
space. Crowdsourcing detection allows thousands of people to go
through each of the observation images in search of new objects.
This contrasts with current detection techniques, which are very
intensive in human intervention, and for which it is impossible to
guarantee that a single person will identify every object that is observed.
A statistical analysis of all the results will produce positive detections the same way an expert would do, provided enough people give their input for each set of observations. This increases the
ability of the observatories to process the images they obtain [34].
In conclusion, we recommend the creation of a dedicated
Threat Monitoring Network over next decade that fulfills the following requirements:
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Increasing sky coverage, especially in the southern hemisphere, by adding a minimum of two optical observatories
in next five to 10 years.
Putting infrared telescopes at Earth-Sun Lagrange points L1
and L2 by 2025 for better scanning.
Time spent observing regions close to the Sun needs to be
increased to detect NEOs on an incoming trajectory from
inside Earth's orbit.
Increasing the knowledge of the behavior and composition
of cometary nuclei.

DEFLECTION
Having an early detailed characterization of the comet, it is possible to adjust the mitigation solution and, with sufficient warning
time, to design an adapt the mission. We have to keep in mind that
JANUARY 2018

there will always be remaining uncertainties regarding the internal
density, porosity, composition, and structure of the object, and deflection techniques that involve landing on the comet may be risky
or even inappropriate [35]. As mentioned earlier, we considered
the kinetic impactor, thermonuclear devices, directed energy systems (DES), gravity tractor, solar concentrator, and asteroid painting. Disruption and deflection are both possible ways to prevent an
object from reaching Earth, and both are possible if decision makers take action ahead of time. Relevant agencies should enhance
several technologies in case of failure in some parts of the systems.
For the nuclear option, authorities should set up several ready-tolaunch nuclear missiles. Furthermore, officials can launch more
than one rocket at the same time to ensure deflection of the target
in case one explosion is not sufficient or successful.
The following recommendations aim to make the optimistic
scenario realistic from the deflection point of view:
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Reaching an adequate TRL for DES.
Conducting space-based tests to validate the thermonuclear
option and achieve a sufficient TRL. We discussed the thermonuclear option in detail during our team project, and what
can be done to create new regulations to use this option as
a strategy to protect our planet. Due to the current international treaties, the thermonuclear option is not an option at
the current stage and thus it was ruled out.
Simulating the ablation process and further analysis of all
potential deflection methods must be undertaken before the
development of any deflection system.
Developing a ground-based ballistic dome solution to enable
more flexibility and a redundant deflection architecture.

GLOBAL COLLABORATION
We believe that every nation bears some responsibility for our actions to protect life on Earth and for our failure to respond. The
lack of current effective planetary defense infrastructure demands
a global collaboration for funding, technical capabilities and for
managing an effective planetary defense program. We discussed
the case when a response to deflect a comet is dominated by one
country as a "go-it-alone" approach, as it may be an option to mitigate small PHO threats with short warning time. The advantages of
a single nation approach could be faster mobilization, decision and
policy making, due to existing bureaucratic structures within the
country. However, such approach may not account for larger space
hazards that may expand to more than one country; in addition,
there is a possibility that a side or partial deflection on a comet or
asteroid may result in diverting the object trajectory and changing
its impact to another region. A comprehensive planetary defense
program must require a multi-national approach due to the large
financial and resource costs and the lack of preparedness.
We encourage global collaboration to mitigate space hazards,
especially PHO hazards, which truly require a robust multinational
response. We also believe that even if a planetary defense mission dominated by a single region, it will still involve significant
international communication, and international technical participa-

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Table of Contents for the Digital Edition of Aerospace and Electronic Systems Magazine January 2018