Simplify the following text for a Grade 11 native English-speaking person.
Original: Huntsville 's economy was nearly crippled and growth came to a near standstill in the 1970s following the closure of the Apollo program , but the emergence of the Space Shuttle and the ever-expanding field of missile defense in the 1980s helped give Huntsville a resurgence that continued into the 21st century .
Simplified: Huntsville 's economy was nearly crippled and growth came to a near standstill in the 1970s following the closure of the Apollo program . The emergence of the Space Shuttle and the ever-expanding field of missile defense in the 1980s helped give Huntsville a resurgence that has continued into the 21st century .