The Apollo 11 command module Columbia has been on display at the Smithsonian's National Air and Space Museum since 1970. But workers there have uncovered marks on the inside of the capsule that provide new insight into the landmark mission.

On July 20, 1969, space history was made as Neil Armstrong and then Buzz Aldrin stepped out of the Eagle lunar lander and became the first men to walk on the moon. While they were on the surface, the Columbia space module, piloted by Michael Collins, was in orbit around the moon waiting for their return. After the moonwalkers had returned to the capsule and it safely landed back on the Earth, it toured the United States and then arrived at its final home at the museum.

As part of a project to completely scan the capsule and make the images available online to the general public, workers uncovered notes and other markings made by the three astronauts who inhabited the capsule during the mission.

"Recently, we have again been reminded that a curator's work is never done," curator Allan Needell wrote on the museum's blog Thursday. The markings were found "in areas of the spacecraft that have been hidden from view for more than 40 years," Needell added.

Needell shared pictures of the freshly discovered graffiti. This first image might look like a series of frantic scribbles from an astronaut needing to rapidly calculate a course correction. But by reviewing audio transcripts of ground-to-space communications, the museum curators determined that the numbers in the lower right were coordinates sent by Houston that Collins was using to try to pinpoint the Eagle's position on the lunar surface. The panel on which he wrote them is left of the navigation station where Collins would have been able to use the capsule's sextant and telescope. He was ultimately unsuccessful in spotting the lander.

Smithsonian Institution

If you look closely at the panel in the upper right of this image, you'll see a note that reads, "Launch day urine bags." According to the museum, the astronauts used this storage locker, labeled R5, to store filled urine bags before the capsule's main waste disposal system came online. Needell suggests that the note was a warning to leave the locker undisturbed.

Smithsonian Institution

Even though the Apollo mission lasted a little over a week, there was at least one astronaut who was counting the days, as can be seen in this hand-drawn calendar. The last day, which was when the capsule splashed down in the Pacific Ocean, remains uncrossed.

"Exactly when this was drawn, by which astronaut, and the purposes it served are a matter of conjecture (and much discussion) since it was noted," Needell says. "We do know that it remains virtually unchanged since the Command Module arrived at the Lunar Receiving Laboratory during the two-week quarantine period enforced on the early Apollo Lunar missions."

Smithsonian Institution

Needell also shared this image in his post, which he says has been known to historians for quite a while and is not part of the new discoveries. Still, he included it because he says it's "a sentiment we have all come to appreciate now more than ever."

Smithsonian Institution

"We will continue to study the secrets Columbia holds, nearly 50 years after it completed its mission and for years to come," said Needell. "As a curator, it is thrilling to know that we can still learn new things about one of the most iconic artifacts in the entire Smithsonian Collection."