Spheres With Ice Shields For Earth-Mars Orbiter?

Buzz Aldrin described a permanent Earth-Mars orbiter that astronauts would catch when it neared Earth and jump off close to Mars. Constructing such a module in space with ice from comets melted to water and put into a shield around a round module as a shield could be feasible.
http://phys.org/news/2013-05-aldrin-colonize-mars.html#inlRlv


I believe 15 feet of ice are needed to stop most GCR’s and SEP’s. Ice already in space would be the cheapest to get perhaps.Injection formed spheres by the thousands could be built in space and provided with modularized components built on Earth, the Moon or maybe asteroids. I would think the mass of solar system planets ought not be changed much.


Researchers are studying radiation from Galactic cosmic rays and solar emitted particles-the first are worse and  the second most common. The Curiosity Rover spacecraft measured radiation in space during the trip to Mars from Earth, arriving in 2012 on the red planet.

http://www.nasa.gov/mission_pages/msl/news/msl20130530.html

 http://phys.org/news/2013-05-exposure-journey-mars.html#jCp

image credit N.A.S.A./Cal Tech/JSC

Artist's concepts shows NASA's Mars Science Laboratory cruise capsule and NASA's Orion spacecraf