text:  From Earth @-@ based radar and spacecraft images of the crater edge , Shackleton appears to be relatively intact ; much like a young crater that has not been significantly eroded from subsequent impacts . This may mean that the inner sides are relatively steep , which may make traversing the sides relatively difficult for a robotic vehicle . In addition , it is possible that the interior floor might not have collected a significant quantity of volatiles since its formation . However other craters in the vicinity are considerably older , and may contain significant deposits of hydrogen , possibly in the form of water ice . ( See Shoemaker ( lunar crater ) , for example . ) 
  