I am a long-ago [1965] graduate of Physics at UCLA and, although most of
my career has been in the area of finance, I still have a great fondness
for the "hard sciences." Recently my grandson, age 9, and I have been
playing a thought game regarding the best way to precisely deflect an
earth-bound asteroid into a benign orbit around the earth. He suggested
using solar energy in some way which led me to the undoubtedly
unoriginal idea of creating an array of space-based square kilometer
solar PV collectors and using their 270 megawatt output [each] to charge
up a megaton class [about 4.17 e+15 joule] flywheel. We picked this
number based on the unscientific guess that a 1 megaton fusion bomb
exploded at an appropriately close distance and with sufficient
lead-time would be able to nudge a 1 km diameter asteroid out of a
collision trajectory with the earth.
To carry the thought game further, we had several questions and wondered
if someone would give us some guidance:
1. How big should such a flywheel be, at what speed would it rotate at
full charge and from what would it be constructed? [I calculated that a
300m diameter flywheel with the density of steel and a mass of about
1.7e+10 kg would store this energy assuming a w of 2 radians/sec, but I
have no idea whether or not it would hold together].
2. What would be the best way, using current technology, to deliver this
energy to the surface of the asteriod? High energy lasers such as the
ones being developed by DOD? Or accelerating hydrogen nuclei [i.e., a
proton beam] at very high relativistic speeds? Or some other way?
Hoping someone will humor us and give us some pointers. Many thanks.
Bill Prescott