The National Aeronautics and Space Administration (NASA) has just sold 2,400 of its rarest and most private images. These involve a picture of Neil Armstrong on the Moon carrying an American flag, Laika in a space capsule holding a puppy, and Buzz Aldrin's selfie. The auction host's blog said they fetched over £1.56 million ($2.1 million) during the event from Nov. 6 until Nov. 20.

The only picture showing Armstrong on the Moon, captured by Aldrin during the 1969 Apollo 11 flight, was one of the most costly things. The auction house sold the photograph for £52,500 ($70,200). 

Photos By NASA Reveal Various Historical Missions

There were a range of historical missions in the series of initial photos, from the Mercury and Gemini spaceflight programs to the Apollo moon missions. Any of the photos are still popular, such as the "Blue Marble" photograph captured by the Apollo 17 crew-the first completely illuminated shot of Earth taken in space by a person.

The costly images span every achievement of the previous missions of the space agency. Analog, which includes light-sensitive chemistry, photographic records, and video, was also used by astronauts.

Of course, together with other National Geographic and Kodak professionals, NASA advised the experts on how to take the images.

"The astronauts-turned-artists were willing, through their cameras, to communicate to mankind the majesty and scope of their space experience, forever transforming the way we view ourselves and our position in the cosmos," Christie's said in the key blog post.

The Most Costly of NASA's Famous Photographs

Other big-lot tickets include "Blue Marble," which the auction house sold for £32,500 ($43,500), and a snapshot of the first "Earthrise" witnessed by humans in orbit, dated 1968, which earned £23,750 ($31,800), were other big-ticket lots. 

For several decades, these unreleased images have been held in the Manned Spacecraft Center collections in Houston. Only certified scholars and other experts may use them. Private owner Victor Martin-Malburet assembled the unique set for nearly 15 years. To see the collection, click here.

Why So Expensive?

When imaging was already analog, the pictures were taken, involving "light-sensitive chemistry, film and photographic paper," the press release said. Along with experts from Kodak and National Geographic, NASA trained the astronauts about how to take images in orbit.

"Through their cameras, the astronauts-turned-artists were able to convey to mankind the beauty and profundity of their experience into space, forever changing the way we see ourselves and our place in the universe," said the release.

Unreleased images have been stored in the collections of the Manned Spacecraft Center in Houston, Texas for decades. Only qualified scholars have been allowed to view them. The pieces, collected by private collector Victor Martin-Malburet over the span of 15 years, have been displayed in museums around the world, including the Paris Grand Palais and the Zurich Kunsthaus. 

ALSO READ: Jupiter's Icy Moon Europa 'Glows in the Dark' Due to Radiation, Scientists Say

Check out more news and information on Space on Science Times.