As NASA prepares to launch shuttle Atlantis -- we're less than one week away before scheduled launch -- NASA hopes to launch the shuttle towards the Hubble Space Telescope on May 11.

The shuttle's seven-man crew will be responsible for five scheduled spacewalks aimed at repairing several systems aboard Hubble, as this is the last shuttle mission to the aging space telescope.  The last Hubble servicing mission was in 2002.

Space.com posted a nice write up of the current challenges NASA faces with the final repair mission to Hubble.

Once repaired to the best of its ability, Hubble should be able to see infant galaxies while also studying 500 years after the big bang, NASA said.

Since the current fleet of shuttles should be retired next year, there won't be a shuttle large enough to transport supplies to the Hubble, which is one of the reasons NASA won't service the telescope again.  The more important reason, however, is that the U.S. space agency is looking forward to the next space telescope it expects to launch into space in a few years.

Since the orbit of Hubble is higher than the International Space Station (ISS) -- and there is more debris that could impact the shuttle -- there is a higher danger risk involved with the Hubble mission.  There is a 1-in-229 chance of space junk harming the shuttle, which is a lower risk than the initial 1-in-185 risk prediction -- anything exceeding 1-in-200 forces NASA to re-evaluate the mission and sign necessary documents to allow the mission to continue.

If an emergency with shuttle Atlantis occurred, NASA will have shuttle Endeavour and its crew ready for launch towards Hubble. 

Assuming all goes according to plan, shuttle Atlantis will return back to Earth and the Hubble Space Telescope will be able to continue to work at least five more years, or until the end of 2014.