Scientists and would-be space men both got a jolting surprise last week. It came from the first detailed official reports on what the two tubular Explorer satellites are discovering.
Intense and unsuspected radiation that would threaten the health of a man exposed to it for two hours has been found in outer space, said Dr James A Van Allen, of the State University of Iowa.
First practical result of the announcement is to raise a barrier against ambitious plans to shoot men into space. Although spaceship proposals already are on the desks of high Government officials, it appears that the blueprints will need to be modified.
Lead shielding — about 100 pounds of it for a one-man space capsule and several tons for a sizable space vehicle — will be required. Until now, it was believed no shielding would be necessary.
Metal vehicles in space are themselves the instruments for producing damaging X rays. In an X-ray machine, rays are produced by aiming a beam of electrons — atomic particles — against a metal plate. Now it is discovered that space is filled with electrons from hydrogen explosions in the sun. Bombardment of the Explorers’ steel shells produce X rays.
This X-ray action begins at an altitude of about 625 miles. One Explorer, swinging up as high as 1,700 miles, reveals that the radiation gets more intense with distance. Dr. Van Allen believes the electron belt is probably about 8,000 miles in thickness. The earth’s surface is shielded from it by a magnetic field that bounces back electrons.
First effect of the X rays upon a space traveler would be genetic damage. Radiation will not cause quick death and probably would not cause nausea and other effects of radiation damage. It would shorten life. Several hours’ exposure would cause temporary blood damage. Long exposure probably would result in leukemia or bone cancer.