Visitors to: http://www.airspacemag.com/space-exploration/Top_NASA_Photos_of_All_Time.html can view the top 31 images.
The following is from the Air and Space Magazine website.
On the occasion of the 50th anniversary of the National Aeronautics and Space Administration, which began its operations on October 1, 1958, we offer this list of the 50 most memorable images from NASA’s history . We recognize that any such ranking is inherently subjective. The rationale for why any one image ranked two slots higher than any other combines several factors, including our attempt to balance the list between human spaceflight, satellite imaging, and planetary exploration. Many wonderful images did not make the final cut—we couldn’t convince the editors to give us 20 pages instead of 10.
The list omits significant events from space history that were not NASA achievements, such as the famous 1958 photograph of Wernher von Braun and the other architects of the Explorer 1 satellite celebrating their success by holding a model of the satellite over their heads, an event that occurred months before NASA existed. Photos from the Apollo moon program predominate, as well they should—it remains the agency’s crowning achievement. We also recognize that, even though the first “A” in NASA stands for “aeronautics,” our list is light on aeronautical breakthroughs (see Moments & Milestones, p. 84). Our only excuse is that the ranking reflects the affinity of the division of space history staff for space topics. (http://www.airspacemag.com/space-exploration/Top_NASA_Photos_of_All_Time.html)