Silicon-containing asteroids can be used to cheaply protect manned ships from radiation - if only we can learn how to extract the necessary minerals from them and conduct construction directly in orbit.
Today, space radiation is one of the key problems that seriously impede the development of manned astronautics outside the Earth orbit. Calculations show that during the journey to Mars and back - even in the absence of extreme events - astronauts will receive the same dose of radiation that ordinary people receive in their entire lives.
Therefore, all projects of such missions provide for one or another method of protection: for example, improved versions of aluminum structural parts that screen radiation on the ISS. However, the higher level of protection makes such shields extremely heavy and ships expensive to launch from Earth. Therefore, Leos Pohl and Daniel Britt propose to use material that can be taken directly in space. Scientists write about this in an article published by the journal Advances in Space Research.
The fact is that some asteroids are quite rich in silicates, which quite effectively absorb particles of cosmic rays and the solar wind - they are mainly made up of protons and helium nuclei (alpha particles). Experiments that Britt and Paul conducted in the laboratory have shown that such silicates are 10 percent more efficient at this task than even aluminum.
Therefore, scientists have voiced the idea to "finish building" ships for manned missions right in flight. Lightweight and unprotected, they will not be so expensive to launch into orbit, after which asteroids will be "adjusted" to them, from which they will then collect the necessary shielding. However, many technical details and complexities associated with this scheme are still unclear. Perhaps solving them will become much more expensive than using good old aluminum or just water.