Re: Protection against Van Allen Radiation


If by "transit through the van Allen belts" you mean going from orbits
below them to orbits above them, then it is possible to do this in such
a way that you avoid most of the radiation (see old post below).

If what you mean is what sort of shielding would it take so a human
could orbit say 50 times through the high radiation part of the belts
and lose less than 1 year of life expectancy, it is really large (my
wild ass guess is well over 5 feet of water). While it is true that
the Earth's magnetic field can not trap the highest energy level
radiation, it can trap so much radiation that it is a really really a
bad place to be.

I have a simulator that can show you how trapped particles move at
http://spacetethers.com/

I also collected some radiation info at
http://spacetethers.com/radiation.html

There is also a proposal to clean out the van Allen belts and reduce
the radiation level by maybe as much as a factor of 100 (link in
previous page).


-- Vince

From: Vincent Cate (vince@xxxxxxxxxxx)
Subject: Apollo and the van Allen belts
Newsgroups: sci.space.policy (very similar to sci.space.science
also)
Date: 2003-11-18 10:53:25 PST

In "The Space Environment" by N. H. Langton (1969) they say the
Apollo plan was to avoid most of the van Allen belt radiation by
going through near the edge. Cape Canaveral is 28.5 degrees North,
which is about right for going toward the Moon. The radiation
belts are inclined about 11 degrees (as is the Earth's magnetic
field) and are about +- 40 degrees wide. If you time your
departure for the Moon so you are at the Northern part of your
orbit while over the longitude where the radiation belts are South,
you can miss most of the radiation. From pages 134-136 I quote:

The problem of making a suitable exit through the trapped radiation
is not in fact particularly difficult. The lunar missions at
present proposed will leave from a parking orbit below the van Allen
region and the most opportune instant to leave this orbit will of
course be chosen. The radiation intensity is quite low at and above
magnetic latitude 40 degrees North or 40 degrees South and the
geomagnetic dipole is at an angle of 11 degrees to the Earth's
rotational axis. The rotational axis is at an angle of 66.5 degrees
to the plane of the ecliptic at the equinoxes and the plane of the
lunar orbit is inclined at 5 degrees to that of the ecliptic,
around which it rotates with a period of just over 18 years.
Accordingly, once every 18 years, at the equinox, there is an
instant each day when a straight line from Earth to the Moon is the
normal at magnetic latitude 39.5 degrees. The situation is shown
in Fig. 4.10. While this ideal path may not be followed (it imposes
considerable restrictions on dates and times of lunar missions, and
takes no account of solar flare incidence) the general principles
involved are clear, and a lunar mission is unlikely to incur
a high dose burden from the van Allen belts on its way from and
to the Earth.

-- Vince

.

Relevant Pages

  • Re: Protection against Van Allen Radiation
    ... a way that you avoid most of the radiation. ... could orbit say 50 times through the high radiation part of the belts ... There is also a proposal to clean out the van Allen belts and reduce ... The lunar missions at ...
    (sci.space.policy)
  • Re: What is the radiation level at the Van Allen belts
    ... Apollo plan was to avoid most of the van Allen belt radiation by ... The lunar missions at ... >present proposed will leave from a parking orbit below the van Allen ...
    (sci.space.tech)
  • Re: Is LIGO just observing viscosity of the vacuum?
    ... orbit around the Sun for 4+ billion years. ... Roughly speaking, it's because electromagnetism allows dipole radiation, ... while gravity allows only quadrupole and higher radiation. ... radiated power goes as the square of the second derivative of the dipole ...
    (sci.physics.research)
  • Re: Space warfare- fighter ship design
    ... low orbit implies HIGH relative velocities. ... While certainly not necessarily, the way orbital mechanics ... >>already need heavy radiation shielding for the crew ...
    (rec.arts.sf.science)
  • Re: What is the radiation level at the Van Allen belts
    ... >Does anyone know what the radiation lever is at the Van Allen Belts.. ... After the unmanned Apollo 4 and Apollo 6 flew with radiation-monitoring ... Astronaut activity in more thinly shielded vehicles ...
    (sci.space.tech)