Possible Clues:

• Lewis or Clark
• Shackleton or Amundsen, say
• Adventurer in little-known regions
• Cabot or Cartier
• Investigative traveller
• Adventurer in unknown regions
• Traveller seeking discoveries
• Dr Livingstone I presume? Find out that it's right
• Eg, Livingstone, Park
• Any of the first series of US satellites