It allowed them to test theories about how those galaxies formed.
Like any other mechanical device, though, Hubble needs periodic tune-ups. As a result, the observatory is maintained by a team of hundreds of scientists, engineers, and computer programmers at the Space Telescope Science Institute the Goddard Space Flight Center. The HST also has regular planned servicing missions. NASA sends astronauts up on the Space Shuttle for maintenance every three years, or sooner if required.
The first major servicing mission came just after launch. Hubble's primary mirror was incorrectly shaped during manufacture, so the telescope could not focus all the light from an object to a single sharp point. Instead, it saw a fuzzy halo around objects it observed, and the images it sent to Earth were pretty much useless. Astronauts were sent up on the space shuttle @Endeavour to catch the telescope, haul it into the shuttle's cargo bay, and install two new devices -- similar in function to ordinary eyeglasses -- to correct the problem.
