Lansing was a native of Chicago, Illinois. After serving more than five years in the Navy, he enrolled at Northwestern University, and majored in journalism. Until 1949 he edited a weekly newspaper in Illinois. Thereafter he joined the United Press and in 1952 became a freelance writer.
Lansing is best known for his book Shackleton's Incredible Voyage, the account of the failed expedition of Sir Ernest Shackleton and his crew to the South Pole in 1914. The book is named after the ship used by Shackleton, the Endurance, and it became a bestseller when it was first published in 1959. Whilst researching the book, Lansing spoke with ten of the expedition's surviving members and was granted access to the journals and personal diaries of eight others in order to get a more complete view of the expedition.