wichita.edu
…And with no shuttle missions to boost it higher into orbit, the relentless action of earth's gravity and the ever so slight friction of the atmosphere, evident even in orbit, together conspired to pull the Hubble toward an uncontrolled reentry, possibly over populated areas. Despite these concerns, it was necessary for NASA to make the difficult…
https://www.wichita.edu/academics/engineering/k12/kansasbest/game-history/2005.php