Space biomagnetics

Astronauts who venture from their spacecraft onto the lunar surface and the surfaces of our neighboring planets will be exposed for a few hours in duration to magnetic-field intensities which are markedly less than that of the earth's field. The intensities of magnetic fields to which they will be exposed while inside their spacecraft can be stated only after completing a detailed survey of the contribution made to these fields by the functioning electronic components of spacecraft. Assessment of individuals regularly working in and exposed continuously for 10 days to magnetic fields less than 100 gammas in intensity indicate that extremely low-intensity magnetic fields encountered during a nominal Apollo moon mission should not affect astronaut health or performance. Careful physiological and psychological observations first on higher primates, then on man exposed to such fields for more prolonged periods of time must be carried out before this conclusion can be drawn for longer exposures.Recent technological advances in propulsion and radiation protection have made it possible that astronauts might also be exposed intermittently to high-intensity, relatively low-gradient magnetic fields during space missions. The duration of such exposures could range from less than an hour if an activated magnetohydrodynamic engine must be serviced, to several days if pure magnetic or plasma-radiation shielding is used for astronaut protection from solar flare radiation. From past experience with personnel who enter high-intensity magnetic fields for brief periods of time in their work, magnetic-field exposures while servicing magnetohydrodynamic engines should not be hazardous to astronauts. On the other hand, past exposures of man and sub-human systems to high-intensity magnetic fields do not indicate whether or not astronauts who are exposed for up to several days to currently estimated magnetic-field intensities associated with pure magnetic or plasma-radiation shielding could suffer impairment of their health or performance. This answer can be obtained only by carefully conducted experiments which closely simulate such exposures, and look closely for physiological, psychological and pathological changes, especially in exposed higher primates, before assessing the response of man to such exposures.Magnetic force is animate or imitates life; and in many things surpasses human life, while this is bound up in the organick body.Prepared under Contract NASr-115 at The Lovelace Foundation for Medical Education and Research, Albuquerque, N.M., U.S.A.