In May 2009, NASA sent a shuttle crew on a risky mission to service the Hubble Space Telescope for the last time. Hubble has enthralled scientists and the public by capturing deep views of the cosmos and a wealth of data from distant galaxies. It has helped lead the search for alien planets and is a crucial tool in one of cosmology's most crucial quests, investigating and mapping the mysterious dark matter that dominates the universe. Now the astronaut servicing team must carry out the first ever in-space repairs of Hubble's defective instruments, a task that requires ingenious engineering fixes and the most intensive spacewalk program of any NASA mission. From training to launch, NOVA presents the inside story of the mission and the extraordinary challenges faced by the rescue crew.