Satgen 548  Radiation and Humans 3  by GM4IHJ (BID SGEN548) 1999-09-25

Given that any space activity involves exposure to radiation damage (
satgens 546 and 547 refer). What can be done to protect the human
crews of space stations and interplanetary ships ? Vital parts of
machinery and electronics can be shielded reasonably effectively using
titanium and other dense metal shields. But this treatment is only
possible on small units where it does not carry a heavy weight
penalty. Human beings are much more difficult to protect, because of
their large size and the wide distribution of vulnerable areas in
their bodies.

Shrouding a whole space ship in a dense thick metallic or liquid
shield is not really practical. Although it might be possible to fit a
small radiation shelter for use in emergencies. But even if this were
possible , it would not give much protection against the heavy
metallic ions which constitute some of the cosmic ray showers likely
to be encountered , particularly in interplanetary space. The problem
in this case being , that while dense shielding might impede heavy
ions , the collision of these ions with the material of the shielding
, can itself result in a shrapnel like cloud of almost as deadly
daughter particles exiting the shield and hitting the occupants.

On earth we are protected by the earths atmosphere and magnetic field.
We cannot expect to duplicate an artificial atmosphere around a space
ship, but it might be theoretically possible to generate a very strong
magnetic field around a space ship.However at least two problems limit
the likely effectiveness of this solution. In that a very large
electric power source would be neccessary unless the field could be
generated in a very cold super conductor, and, it is by no means clear
that human being can function for an extended period in a very strong
magnetic field. There may in fact be serious medical consequences if
humans on an interplanetary flight of several years duration , were
forced to live in a strong magnetic field. So there has recently been
discussion of a quite different approach to radiation protection. Most
people will be familiar with the body armour worn by Xray technicians
and Dentists. Could astronauts be persuaded to wear similar protection
for long periods? Or might it be possible to use pharmacological
drugs, either to afford some protection as in certain sunburn
preventative medications, or to assist with speedy recovery from
tissue damage via certain vitamin preparations or other drugs .

Summary.    At this time we simply do not know enough about the
subject to provide long term protection or, adequate short term
protection in the case of major storms. So it comes as no surprise
that the International Space station will be the site of several long
term experiments targetted at getting more information. Matroska , a
manikin of the human torso from the waist up , minus arms, will be
instrumented and fitted with a variety of materials , and placed on a
platform attached to ISS. The experiment will be a long term one , at
least 3 years. By which time we may have more useful facts , although
the developement of even partially effective protection is probably
some way further in the future.