Plans for human Moon exploration began during the Eisenhower administration. In a series of mid-1950s articles in "Collier's" magazine, Wernher von Braun had popularized the idea of a crewed expedition to establish a lunar base. A human Moon landing posed several daunting technical challenges to the US and USSR. Besides guidance and weight management, atmospheric re-entry without ablative overheating was a major hurdle. After the Soviets launched Sputnik, von Braun promoted a plan for the US Army to establish a military lunar outpost by 1965.