— Neil Armstrong had a secret stash of moon landing mementos.

The first man to walk on the moon kept a bag full of small parts from the lunar module "Eagle" that he and his Apollo 11 crewmate Buzz Aldrin famously piloted to a landing at Tranquility Base on July 20, 1969. The stowage bag was discovered by Armstrong's widow after he died in 2012.

"I received an email from Carol Armstrong that she had located in one of Neil's closets a white cloth bag filled with assorted small items that looked like they may have come from a spacecraft," Allan Needell, the Apollo curator at the National Air and Space Museum in Washington, DC, wrote in a blog published on Friday (Feb. 6). "Needless to say, for a curator of a collection of space artifacts, it is hard to imagine anything more exciting."

The bag, itself flown to the moon, was referred to as the "McDivitt purse," after the Apollo 9 astronaut whose idea it was to include it aboard the spacecraft.

Its contents, identified by Needell and the team behind the Apollo Lunar Surface Journal, included Armstrong's waist tether, utility lights and their brackets, equipment netting, an emergency wrench, the optical sight that was mounted above Armstrong's window and the 16mm data acquisition camera (DAC) that recorded the now iconic footage of the lander's final approach and Armstrong's descent down the ladder to take his "small step" onto the moon.

"The 16mm DAC, given the images that it captured, ranks as enormously important," Needell told collectSPACE. He noted though, that all of the items have added significance given their connection to Armstrong.

For whatever reason, Armstrong seemingly kept the bag a secret for more than four decades. Even when questioned about mementos by his authorized biographer, Armstrong made no mention of the historic artifacts that were tucked away in his closet.

To be clear, the bag was not something Armstrong snuck home from the moon. After returning to lunar orbit, the bag and its contents were moved from Eagle to the command module "Columbia" before the lander was directed to crash back to the surface. Had the purse remained aboard, it too would have been destroyed.

Armstrong mentioned the purse to command module pilot Michael Collins as it was being transferred from one craft to the other.

"That [is] just a bunch of trash that we want to take back — LM parts, odds and ends," Armstrong said.

Later, Collins called Mission Control to note where the bag was being placed for the trip home and about how much it weighed.

It is not known how the purse came to be in Armstrong's possession after the mission, but it wasn't unusual for the astronauts to retain small spent parts of their capsules as souvenirs. In September 2012, one month after Armstrong died, President Barack Obama signed into law a bill that confirmed the Mercury, Gemini and Apollo astronauts had legal title their mementos.

For now, the purse and its contents are on extended loan from the Armstrong estate to the Smithsonian, though the intention is to eventually donate them to the museum. In addition to the McDivitt purse, the family has also offered an extensive collection of Armstrong's personal items and memorabilia.

Two of the artifacts, the data camera and waist tether, are already on display at the National Air and Space Museum as part of the new exhibition, "Outside the Spacecraft: 50 Years of Extra-Vehicular Activity," which is open through June. The tether was designed to be used in the case of an emergency spacewalk but instead Armstrong used it to suspend his legs while trying to rest inside the lander (a determination that the Apollo Lunar Surface Journal team made by inspecting the rediscovered artifact).

Eventually, the Armstrong purse and many, if not all of its contents may be put on display as part of the museum's planned renovation of its Apollo-dedicated gallery.

The photo above (sans numbering) was provided to National Air and Space Museum curator Allan Needell by Carol Armstrong and shows the bag and its contents after their discovery. Numbering was added by the Apollo Lunar Surface Journal. See below for detailed photos of the artifacts, referenced by number.

1. The Apollo 11 temporary stowage bag, above and below, referred to as the "McDivitt purse" after the Apollo 9 astronaut James McDivitt whose idea it was to include it aboard the lunar module.

1. Apollo 11 temporary stowage bag.

2. The orange-colored Data Acquisition Camera (DAC) electrical cable as seen during the Apollo 11 mission.

2. Data Acquisition Camera (DAC) power cable and its connector.

3. Apollo 11 training photo showing Armstrong in a lunar module simulator. One of the utility lights is above him.

3. Utility light with power cable.

4. Utility light with power cable.

5. Utility Bracket Assembly (also known as a Utility Clamp).

6. Utility Bracket Assembly (also known as a Utility Clamp).

7. Apollo 11 mission photo showing the Crewman Optical Alignment Sight (COAS) installed above Armstrong's window onboard the lunar module Eagle. The COAS was used by Armstrong for rendezvous, docking, star sightings, and horizon alignment.

7. Crewman Optical Alignment Sight (COAS).

8. Crewman Optical Alignment Sight (COAS) filter with casing.

9. Crewman Optical Alignment Sight (COAS) spare light bulb assembly.

10. This waist tether was designed to be used in the case of an emergency spacewalk. Armstrong used it to suspend his legs while trying to rest inside the lander (a determination that the ALSJ team made by inspecting the rediscovered artifact).

11. Helmet tie-down straps.

12. The 16mm Data Acquisition Camera (DAC) was used to record the now iconic footage of Armstrong's descent down the ladder to take his "small step" onto the moon.

12 (12a and 12b). The Data Acquisition Camera (DAC) was mounted on brackets at either of two locations for views through Buzz Aldrin's window of the final approach to landing, Armstrong's climb down the ladder, moonwalk (EVA) activities in the camera field-of-view, and the ascent from the lunar surface.

13. Lens shade (Teflon) for Data Acquisition Camera DAC 10-mm lens.

14. Alignment Optical Telescope (AOT) eyeguard assembly.

15. The mirror was positioned to give Armstrong a view of the Crewman Optical Alignment Sight (COAS) when the latter was mounted in the rendezvous window during approach and docking. Without the mirror, he'd have had to lean a long way back.

15. Mirror (front).

16. Tool B (emergency wrench) was a modified Allen-head L-wrench. The wrench was onboard for contingency use with the docking probe and drogue, and for opening the command module's hatch from the outside.

17. Cover to the waste management (urine-collection) system.

18. This netting was mounted vertically next to Buzz Aldrin's flight station to protect pipes, conduits and other gear.