(Submitted June 30, 1997) How is it possible for manned space
flights to survive the effects of the Van Allen Radiation Belt?
As you know, the Van Allen radiation belts are doughnut-shaped
regions encircling Earth and containing high-energy electrons
and ions trapped in the Earth's magnetic field. Explorer I,
launched by NASA in 1958, discovered these two regions of
intense radiation surrounding the Earth. They are referred to as
the inner and outer Van Allen radiation belts, after James Van
Allen who designed Explorer I. The inner region is centered at
about 3000 km above Earth and has a thickness of about 5000 km.
The outer region is centered at about 15,000 -- 20,000 km above
the surface of the Earth and has a thickness of 6,000 -- 10,000
km. Typically, manned space flight (such as the Shuttle) stays
well below the altitude of the van Allen radiation belts. Safe
flight can occur below altitudes of 400 km or so. SO ...what do
we do when we have to fly through the radiation belts -- like
when we went to the