Simplify the following text for a Grade 9 native English-speaking person.
Original: The U-2 came to public attention when CIA pilot Francis Gary Powers was shot down over Soviet territory on 1 May 1960 , causing the U-2 incident .
Simplified: The United States wanted to keep the purpose of the U-2 secret , but on May 1 , 1960 , Francis Gary Powers was shot down in his U-2 by a Soviet SAM SA-2 missile .