Defending Planet Earth [from space asteroids

Defending Planet Earth [from space asteroids] 15 page presentation from Future of Space Operations talk

4 approaches depending on circumstances

* Civil defense (evacuation, sheltering, first aid, etc.
– Up to 50 meter in diameter?

* Slow Push-Pull (tug, solar heating, albedo change, gravity tractor, et al.)
– Needs decades to operate (plus time to build, etc.)
– Max size 300-600 m diameter
– Gravity tractor closest to ready and least dependent on properties of NEO

* Kinetic Impacts (Super Deep Impact)
– sensitive to porosity of top meters to tens of meters
– momentum transfer efficiency not known
– much wider range of applicability (max size 1 to 1.5 km, shorter warning for small ones)

*Nuclear blast
– standoff blast best
– works up to 10 km and relatively short warning

What Next

* Don Quixote-like mission
– a rendezvous spacecraft at a small NEO followed by a large impactor
– biggest gain in knowledge directly related to mitigation
– Guess $1.5G; Good for international collaboration

* Gravity tractor demonstration
– fewer unknowns other than engineering
– second priority

* Apophis a possible target but any small NEO will do
– Can’t predict which might need to be used first
– Small NEO is by far the most likely
– Warning time very uncertain but short warnings are likely at ~100m diameter or less

Research Needs

– Momentum transfer
– Warning times
– Tails of orbital distribution
– NEO properties – spin and shape, multiplicity, and especially porosity and density
– lots for science but not so much for hazard mitigation
– hence radar programs at Arecibo and Goldstone
– Physics of airbursts
– search strategy – death plunge vs. full survey
– Effects of the wide range of NEO properties on the mitigation strategy
– tsunami generation
– NEO disruption

Planetary Defense and NEO Exploration (26 pages)

The Near-Earth Object Survey spacecraft proposed by Ball Aerospace would prowl for hazardous NEOs and astronaut targets from a Venus-like orbit. The Target NEO workshop recommended NASA compete such a survey telescope as its earliest and highest priority exploration precursor mission. (Ball Aerospace)

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