The last servicing mission to HST; when it occurred, what was done (briefly!), and why it almost didn’t happen at all.

Question

The last servicing mission to Hubble Space Telescope; when it occurred, what was done (briefly!), and why it almost didn’t happen at all.

Answer 1

The final HST servicing mission took place in May 2009. Astronaut spacewalks replaced two instruments, repaired two others, replaced the gyros critical to pointing the telescope, and attached rockets so that when HST eventually starts burning up in the atmosphere, its path can be directed away from populated areas.

The mission almost did not take place because of safety concerns following the burn-up of shuttle Discovery in 2003, the only mission since then that launched into an orbit from which the ISS could not be reached in case of problems.