Question:  Shackleton is an impact crater is named after Antarctic explorer Ernest Shackleton, a polar explorer who led three British expeditions to where?
Context: Sir Nicholas John Shackleton FRS (23 June 1937 – 24 January 2006) was an English geologist and paleoclimatologist who specialised in the Quaternary Period.  He was the son of the distinguished field geologist Robert Millner Shackleton and great-nephew of the explorer Ernest Shackleton. The Shackeltons are a post-punk band from Chambersburg, Pennsylvania.  Despite the spelling, they are named after the Antarctic explorer Ernest Shackleton. Sir Ernest Henry Shackleton ( ; 15 February 1874 – 5 January 1922) was a polar explorer who led three British expeditions to the Antarctic, and one of the principal figures of the period known as the Heroic Age of Antarctic Exploration.  Born in Kilkea, Athy, County Kildare, Ireland, Shackleton and his Anglo-Irish family moved to Sydenham in suburban south London when he was ten.  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. Ernest Edward Mills Joyce AM (about 1875 – 2 May 1940) was a Royal Naval seaman and explorer who participated in four Antarctic expeditions during the Heroic Age of Antarctic Exploration, early in the early 20th century.  He served under both Robert Falcon Scott and Ernest Shackleton.  As a member of the Ross Sea party in Shackleton's Imperial Trans-Antarctic Expedition, Joyce earned an Albert Medal for his actions in bringing the stricken party to safety, after a traumatic journey on the Great Ice Barrier.  He was awarded the Polar Medal with four bars, one of only two men to be so honoured, the other being his contemporary, Frank Wild. Shackleton is a 2001 British television film written and directed by Charles Sturridge and starring Kenneth Branagh as explorer Sir Ernest Shackleton.  The film tells the true story of Shackleton's 1914 Antarctic expedition on the ship "Endurance".  The cast includes Kevin McNally, Lorcan Cranitch, Embeth Davidtz, Danny Webb, Matt Day and Phoebe Nicholls (also the director's wife) as Lady Shackleton.  It was filmed in the UK, Iceland and Greenland.  The film used first-hand accounts by the men on the expedition to retell the story.  Shackleton biographer Roland Huntford was a production advisor. Mullins Valley ( ) is a four mile long valley located at 5,400 ft elevation in the McMurdo Dry Valleys.  It is one of the few dry valleys in the world to contain rock glaciers.  US Antarctic Program (USAP) research has dated the subsurface ice in Mullins Valley at 4 million years old making it among the oldest ice on earth.  United States Antarctic Program (USAP) research has also shown the rock glaciers in the valley to be analogous to the Arsia Mons region on Mars.  Named for Jerry L. Mullins, Physical Scientist, Director, Polar Programs, Antarctic and Arctic Program for United States Geological Survey (USGS), National Science Foundation Antarctic geophysical research, and U.S Scientific Committee (SCAR) delegate to SCAR SCAGI committee.  Appointed by the National Academy of Sciences, Polar Research Board.  His was responsible for Antarctic field research in the Transantarctic Mountains, McMurdo Dry Valleys, Shackleton Mountains, Beardmore Mountains, Antarctic Peninsula, Mount Siple, Amundsen-Scott South Pole station and at deep field research locations in West Antarctica.  His program conducted research in the disciplines of global positioning systems, geodesy, crustal motion, glacial geophysics, airborne geospatial systems, airborne geophysics, seismology, light radar (lidar), topographic mapping and he managed the USGS South Pole winter-over program from 1989 to 1994.  He was appointed by the National Academy of Sciences, Polar Research Board as a US delegate to the Scientific Committee on Antarctic Research Geosciences Standing Scientific Group from 1995–July 2012 and was appointed as a member of the Advisory Committee on Antarctic Names in 1994.  Mullins Valley appears in the Antarctic research literature, on the maps from the British expedition of Captain Scott and in aerial photographs from the United States expedition Operation Highjump by Admiral Byrd.  Mullins Valley, Mullins Lake, Mullins Glacier, and Mullins Geodetic Station, Antarctica are named for United States polar explorer and researcher Jerry L. Mullins. Lieutenant Colonel Eric Stewart Marshall {'1': ", '2': ", '3': ", '4': "} (1879 – 1963) was a British Antarctic explorer with the Nimrod Expedition led by Ernest Shackleton in 1907-09, and was one of the party of four men (Marshall, Shackleton, Jameson Adams and Frank Wild) who reached Furthest South at on 9 January 1909. Shackleton is an impact crater that lies at the south pole of the Moon.  The peaks along the crater's rim are exposed to almost continual sunlight, while the interior is perpetually in shadow (a Crater of eternal darkness).  The low-temperature interior of this crater functions as a cold trap that may capture and freeze volatiles shed during comet impacts on the Moon.  Measurements by the Lunar Prospector spacecraft showed higher than normal amounts of hydrogen within the crater, which may indicate the presence of water ice.  The crater is named after Antarctic explorer Ernest Shackleton. Shackleton Coast is that portion of the coast along the west side of the Ross Ice Shelf between Cape Selborne and Airdrop Peak at the east side of Beardmore Glacier in Antarctica.  Named by New Zealand Antarctic Place-Names Committee (NZ-APC) in 1961 after Sir Ernest Shackleton.  He accompanied Scott on the southern journey during the "Discovery" expedition (1901–04) and subsequently led three Antarctic expeditions.  On the British Antarctic Expedition (1907–09), Shackleton discovered the area beyond Shackleton Inlet to the Beardmore Glacier, and was the first to find a practicable route to the South Pole.  Lack of food stopped him 97 miles (180 km) from his goal. Endurance is an impact crater lying situated within the Margaritifer Sinus quadrangle (MC-19) region of the planet Mars.  This crater was visited by the "Opportunity" rover from May until December 2004.  Mission scientists named the crater after the ship "Endurance" that sailed to the Antarctic through the Weddell Sea during the ill-fated 1914-1917 Imperial Trans-Antarctic Expedition, considered to be the last expedition of the Heroic Age of Antarctic Exploration organized by Ernest Shackleton.
Answer: the Antarctic