SHIELDING PROBLEM FOR HIGH SPEED SPACECRAFT

(Posting a second time; first one did not appear)

You don't even want to run into a micrometeorite at one million mph.
With net resources also available, I'm refering to "The Starflight
Handbook: A Pioneer's Guide to Interstellar Travel," by Eugene Mallowe
and Gregory Matloff (1989)
http://search.barnesandnoble.com/The.../9780471619123
, at the moment.

In the chapter "The Interstellar Medium," pp. 161-171, hardcover
edition, the authors discuss the problem of "starship erosion." Some
of this is relevant to high speed, solar system travel. Without
refering to anyone else, I can think of avoiding damage by contacting
things in space as being divided into three parts: 1 - fine grains
that can be redirected 2- larger objects that must be pulverized 3-
even larger objects that must be detected well enough in advance and
navigated around.

1 - redirecting fine grains: if you could magnetize or charge them and
redirect them with a magnetic field or have them scattered away
harmlessly by some other type of shied - that would be good. (The
authors also mention "screens" of different materials.)

2 - maybe some kind of particle beam to zap larger objects (say
visible to the naked eye but still low enough in mass to be
neutralized this way). Maybe even the propulsion technology for the
engine could be used on a small scale with a beam in front; on
deceleration. Engine exhaust itself might useful, but these objects
may have to be specifically detected and have part of the exhaust
partticle stream (or whatever) directed at them.

3 - For large/massive enough objects, including undetected planetoids,
etc!: must detect them far enough in advance to temporarily alter
course.

"Handbook:" Another interstellar navigational hazard was postulated by
radio astronomer john Wolfe of the NASA Ames Research Center. As well
as the more common 0.1 micron and lesser dust grains, it is possible
that rare hailstone-size particles (about 100 gram) exist in regions
of interstellar space. Because the collision of such objects and a
speeding starship would be catastrophic, and because PASSIVE
protection via as massive forward shield would be prohibitive, ACTIVE
measures might have to be provided. Perhaps a forward-pointing
millimeter-wave radar coudl be used to watch for these interstellar
'golfballs.' If one was found to be approaching, a high-power beamed
energy device - a light or X-ray laser or a neutral particle beeam -
coould be used to disintegrate or deflect the potential interstellar
mine." (p. 170)

Again, the authors are talking about INTERSTELLAR whereas I'm talking
about PLANETARY. But the problem is somewhat shared between a one
million mph planetary ship and a relativistic interstellar ship. Note,
again, also, that radar and beam also have to point REARWARD during
decelaration.