What is NASA currently considering as possible ways to decrease the impact of radiation during longer space missions?

The correct answer to this open question is the following.

As complicated Missions such as the ones to Planet Mars are prepared, NASA is currently considering possible ways to decrease the impact of radiation during longer space missions.

Planet Mars doesn't have a global magnetic field to defect energetic particles, so astronauts have to protect from Sun's radiation and galactic cosmic rays radiation. The two types of protection that NASA is devising are, the use of more mass of traditional material to build the spacecraft and the use of more efficient shields, and for this, NASA needs to invest more money to find the right kind of material that can add protection to the shields.

One category mentioned was creating an advanced, new radiation shielding. Problem with new shielding is that it has weight associated with it. The added weight could cause problems on a long space mission.