Simplify the following text for a Grade 7 native English-speaking person.
Original: Gerard Kitchen O'Neill ( February 6 , 1927 â `` April 27 , 1992 ) was an American physicist and space activist .
Simplified: Gerard Kitchen â Gerryâ Oâ Neill ( February 6 , 1927 â `` April 27 , 1992 ) was an American scientist .