The various instrumental failures over the past few years had reduced Hubble to being a telescope that could only take images. Those images have been fantastically useful, scientifically. However, much of astrophysics requires spectroscopy, which analyzes how much light an object emits as a function of wavelength.
Andrew Feustel and John Grunsfeld have now successfully installed the Cosmic Origins Spectrograph (COS). UV spectroscopy has now returned! (provided the instrument actually, um, works).
They’re currently stowing the bit they took out to make room for COS, and then will move on to the very challenging repair of the Advanced Camera for Surveys (ACS). At this point, even if the two upcoming instrument repairs fail, the telescope is in great shape for many more years of science!
UPDATE: They just announced that ACS passed the “aliveness” test, finishing up ahead of schedule. Unbelievable.