Simplify the following text for a Grade 11 native English-speaking person.
Original: In 1991 , 2001 : A Space Odyssey was deemed culturally significant by the United States Library of Congress and selected for preservation in the National Film Registry .
Simplified: In 1991 , it was thought to be `` culturally , historically , or aesthetically significant '' ( i.e. important for culture , history and aesthetics ) by the United States Library of Congress and was chosen to be kept in their National Film Registry .