text:  From the perspective of the Earth , this crater lies along the southern limb of the Moon , making observation difficult . Detailed mapping of the polar regions and farside of the Moon did not occur until the advent of orbiting spacecraft . Shackleton lies entirely within the rim of the immense South Pole @-@ Aitken basin , which is one of the largest known impact formations in the Solar System . This basin is over 12 kilometers deep , and an exploration of its properties could provide useful information about the lunar interior . 
  