Servicing missions
The Hubble Space Telescope was the first spacecraft designed to be maintained, upgraded and repaired by astronauts while still in space. Over the years, it’s had five such servicing missions all staged from the Space Shuttle. Before each, astronauts trained rigorously, simulating the spacewalks required and testing the hardware to be installed.
During these missions the Space Telescope Operations Control Centre (STOCC) placed Hubble into hibernation and closed the cover to protect its optical equipment. They then manoeuvred the telescope into position where the Shuttle’s robotic arm could grab the telescope and place it in the payload bay. With Hubble anchored in place, astronauts could undertake three to five spacewalks to install new instruments or repair existing ones.
Ground crew would then test the new additions before preparing Hubble for release. The Shuttle would often boost the telescope into a higher orbit to prolong its life, as atmospheric drag is slowly bringing the telescope closer to crashing. The robotic arm would then release Hubble, and STOCC would reopen the aperture door and check all was working as it should. It usually took a few months of further testing before Hubble was back to full science operations after a servicing mission.