The spacecraft was similar to one that would carry humans, and scientists were interested in measuring galactic cosmic rays and solar energetic particles on the trip.

CNN: SHARE THIS

Astronauts would also be bombarded with solar energetic particles, which get accelerated close to the sun as a result of solar flares and coronal mass ejections that shoot portions of the sun into space.

CNN: SHARE THIS

The Sun's magnetic field and solar wind - mainly in the form of electrons and protons coming out of the Sun - protects the entire Solar System by acting as a sort of shield from cosmic rays (very energetic particles and radiation from outer space).

BBC: Viewpoint: The Sun and climate change