2008 Supplement: Frascati Workshop 2007 / Fargion

Asteroid Deflection: How, Where and When?

D. Fargion


To deflect impact-trajectory of massive and spinning km^3 asteroid by a
few terrestrial radiuses one need a large momentum exchange. The
dragging of huge spinning bodies in space by external engine seems
difficult or impossible. Our solution is based on the landing of multi
screw-rockets, powered by mini-nuclear engines, on the body, that dig a
small fraction of the soil surface to use as an exhaust propeller,
ejecting it vertically in phase among themselves. Such a mass ejection
increases the momentum exchange, their number redundancy guarantees the
stability of the system. The slow landing (below ≃ 40 cm s^{-1})
of each engine-unity at those very low gravity field, may be achieved by
safe rolling and bouncing along the surface. The engine array tuned
activity, overcomes the asteroid angular velocity. Coherent turning of
the jet heads increases the deflection efficiency. A procession along
its surface may compensate at best the asteroid spin. A small skin-mass
(about 2×10^4 tons) may be ejected by mini-nuclear engines. Such
prototypes may also build first safe galleries for humans on the Moon.
Conclusive deflecting tests might be performed on remote asteroids. The
incoming asteroid 99942 Apophis (just 2% of km^3) may be deflected
safely a few Earth radiuses. Its encounter maybe not just a hazard but
an opportunity, learning how to land, to dig, to build and also to nest
safe human station inside. Asteroids amplified deflections by gravity
swing may be driven into longest planetary journeys, beginning i.e. with
the preliminary landing of future missions on Mars' moon-asteroid Phobos
or Deimos.


asteroids: deflection spin gravity swing nuclear energy

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