What is the best airfoil to use in the thin martian atmosphere and would a solar electric propeller driven propulsion system work sufficiently enough to propel such a platform?

What if any economical methods of shielding manned missions exist to protect the crew from cosmic and solar radiation for the structures built on Mars?

I keep hearing that the plans to build a base on Mars from NASA have been cancelled. Is this true? I am not finding sources online for this anywhere and am having very little luck finding anything on Nasa.gov.