Chapter 8: Mitigation Possibilities

"Long period comets present new dimensions of difficulty. By definition, such comets have never
been seen before. They come unpredictably at all angles from the outer reaches of the Solar System, but can usually only be seen when at a distance of about 5 AU from Earth. Warning of the approach of such a body could well be less than a year. Urgent measures and even more powerful rockets and explosives would then be essential."

Spaceguard Survey Chapter 2.2 The Relationship of Risk to Size of Impactor

"Comets are composed in large part of water ice and other volatiles and therefore are more easily fragmented than rocky or metallic asteroids. In the size range from 100 m to 1 km, a comet probably cannot survive passage through the atmosphere, although it may generate atmospheric bursts sufficient to produce local destruction. This is a subject that needs additional study, requiring a better knowledge of the physical nature of comets."

I should have said the threat from long period comets is not from small impactors not "comets are not small impactors"

Spaceguard Survey Chapter 2.5 Conclusions

"As a first step toward significant reduction of this hazard, we need to identify potential asteroidal impactors larger than 1 km diameter. In addition, attention should be given to the inherently more difficult problem of surveying as many potential "new" cometary impactors of similar equivalent energy as is practical. As noted in Chapter 5, the comets account for 5-10 percent of impactors in this size range. However, because of their greater impact speeds, these comets could contribute as much as 25 percent of the the craters larger than 20 km in diameter"

Relevant only because EP used to ignore this issue until he found a way to tag his moonbase desires on it.

Spaceguard Survey 3.4 Physical Properties of NEOs

"For a study of impacts, it is not essential to know a great deal about the physical nature of comets and asteroids. The most important properties are simply their mass and impact velocity, although it would make a difference if the projectile were double or multiple and easily came apart as it entered the atmosphere. However, any future program for intercepting and diverting an incoming comet or asteroid will require detailed knowledge of the configuration, density, cohesion, and composition of these objects. For these reasons, in addition to their significance for basic science, spacecraft missions to comets and near-Earth asteroids are essential. The first opportunity for a detailed study of a comet is provided by the NASA Comet Rendezvous and Asteroid Flyby mission (CRAF), now planned to study Comet Kopff in 2002 (CHECK). The opportunity for a similar study of a near-Earth asteroid will depend on approval of the NASA Discovery line of small planetary missions, the first of which is to be an asteroid rendezvous. "

Relevant to EP's handwaving we know how to deal with the problem BS

Spaceguard Survey 5.6.2 Discovery Completeness - Comets

"No survey can aspire to completeness in the discovery of ECCs, since new comets are constantly entering the inner solar system. Results for ECCs in a 6,000-square-degree per month survey to V = 22 and 24 are given in Table 5-4. As before, calculations are for a perpetual survey."

Comet/Asteroid Protection System (CAPS)

"RASC goal - develop a system concept that maximizes the range of detectable objects
(size and/or distance), and provides a high probability that the objects will be detected
with significant warning time, even upon their first observed near-Earth approach.
– 1+ km NEOs 5-7 AU from Earth (1 AU = 150 million km)
– 50+ m NEOs < 1 AU from Earth"

5-7 AUs is still minimal warning as noted in the first reference. We can detect them now at that distance RASC would only assure that a much higher percentage would be detected at that time.

"The CAPS study team is focusing on three different detection architectures to accomplish
the mission functions:
– Lunar surface based
– Heliocentric orbit (nominally at 1AU – potentially Lagrange points)
– Earth orbiting

CAPS could utilize existing/future Earth ground-based assets. Future dedicated facilities,
such as the Large-Aperture Synoptic Survey Telescope, could be linked.

The placement of CAPS assets is greatly influenced by assumptions regarding the
availability of synergistic space infrastructure (e.g., Lunar base). The final system may be
configured with elements at various locations."

Note the huge assumption regarding "the availability of synergistic space infrastructure (e.g., Lunar base)" that EP always ignores. The authors do not claim the Moon option is the most cost effective as a stand alone project as EP does.

Regards,
Mark