Remember the crazy idea to build an elevator to space? Scientists now report that without proper shielding such an elevator can't be used by humans because of high doses of ionising radiation passengers would receive when traveling through the core of the Van Allen radiation belts around Earth.
"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.
There are some solutions for the radiation problem, but all of them come with drawbacks.