17 December 2004: GAO Report: Space Shuttle – Costs for Hubble Servicing Mission and Implementation of Safety Recommendations Not Yet Definitive
“Although a shuttle servicing mission is one of the options for servicing the Hubble Space Telescope, to date, NASA does not have a definitive estimate of the potential cost. At our request, NASA prepared an estimate of the funding needed for a shuttle servicing mission to the Hubble. NASA estimates the cost at between $1.7 billion to $2.4 billion. However, documentary support for portions of the estimate is insufficient.”
