Solar wind is a stream of particles emitted continually from the sun.
It will hit the Genesis spacecraft and push through the surface. Inside meaning inside the material of the spacecraft. The spacecraft is made of super clean stuff, so the scientists will know that anything that is more than what went out into space must be pieces of the sun. Chemists studying these samples determined the abundances of a few elements in the solar wind at the surface of the moon. The space station Skylab found the origin of the fast solar wind in 1973-1974.