Hubble Space Telescope
Challenger disaster, delays, and eventual launch

By January 1986, the planned launch date for Hubble that October looked feasible, but the Challenger disaster brought the U.S. space program to a halt, grounded the Shuttle fleet, and forced the launch to be postponed for several years. During this delay the telescope was kept in a clean room, powered up and purged with nitrogen, until a launch could be rescheduled. This costly situation (about US$6 million per month) pushed the overall costs of the project higher. However, this delay allowed time for engineers to perform extensive tests, swap out a possibly failure-prone battery, and make other improvements. Furthermore, the ground software needed to control Hubble was not ready in 1986, and was barely ready by the 1990 launch. Following the resumption of shuttle flights, Space Shuttle Discovery successfully launched the Hubble on April 24, 1990, as part of the STS-31 mission.

At launch, NASA had spent approximately US$4.7 billion in inflation-adjusted 2010 dollars on the project. Hubble's cumulative costs are estimated to be about US$11.3 billion in 2015 dollars, which include all subsequent servicing costs, but not ongoing operations, making it the most expensive science mission in NASA history.
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