Question:  Shackleton is an impact crater is named after Antarctic explorer Ernest Shackleton, a polar explorer who led three British expeditions to where?
Sentence (from "Ernest Shackleton"): His first experience of the polar regions was as third officer on Captain Robert Falcon Scott's Discovery Expedition 1901–1904, from which he was sent home early on health grounds, after he and his companions Scott and Edward Adrian Wilson set a new southern record by marching to latitude 82°S.
Relevant evidence: No