[ RadSafe ] Space elevators: 'First floor, deadly radiation!'

[Dawson, Fred Mr]

>From New Scientist
http://space.newscientist.com/article/dn10520-space-elevators-first-floo
r-deadly-radiation.html
Space elevators are touted as a novel and cheap way to get cargo, and
possibly people, into space one day. So far, they have barely left the
drawing board, but ultimately robots could climb a cable stretching
100,000 kilometres from Earth's surface into space.
But there is a hitch: humans might not survive thanks to the whopping
dose of ionising radiation they would receive travelling through the
core of the Van Allen radiation belts around Earth. These are two
concentric rings of charged particles trapped by Earth's magnetic
fields.
"They would die on the way through the radiation belts if they were
unshielded," says Anders Jorgensen, author of a new study on the subject
and a technical staff member at Los Alamos National Laboratory, New
Mexico, US. 
Space elevators had been planned to be anchored on an ocean platform
near the equator, with the other end tied to a counterweight in space.
At the equator, the most dangerous part of the radiation belts extends
from about 1000 to 20,000 kilometres in altitude. The region did not
hurt the Apollo astronauts in the 1960s and 1970s because their rockets
delivered them swiftly through it. 
For a space elevator travelling at the current proposed speed of 200
kilometres per hour, however, passengers might spend half a week in the
belts. That would hit them with 200 times the radiation experienced by
the Apollo astronauts.


Fred Dawson
Fwp_dawson at hotmail.com