What caused mysterious gray spots to appear on Neil Armstrong's Apollo 11 moon landing glove?

Neil Armstrong's gloves from the Apollo 11 mission moon landing were displayed at the Smithsonian National Air and Space Museum in 2012. Visitors took notice of gray patches on Armstrong's right glove.

The staff was confronted with a question: What are those spots?

Scientists thought they had solved the years-old mystery with an analysis on the gloves and their gray spots.

The spotting was caused by lunar dust trapped between the cloth and coating, according to a 2016 Smithsonian news release.

The cloth that the gloves are made from is fragile, they said, and requires repairs. Lisa Young, lead conservator of the space suits, compared the repair process to adding a clear coat of nail polish at the end of a manicure for protection.

Researchers noticed similar spots on Armstrong's space suit itself, and related documents revealed repairs made to the suit that caused the spots.

Experts believe the repairs to the suit were made preflight, leaving them susceptible to lunar dust. The lunar dust went through the coating, which is softer than the original material, and became stuck underneath. It did not penetrate the suit or glove itself.

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Lunar dust is angular the consistency is glass like, Young said. It's made of iron, calcium and other elements. NASA described the feeling of it as "soft like snow, yet strangely abrasive."

"It's just really sharp because there's no atmosphere up there," she said.

And protection from lunar dust would have been important for Armstrong and the other astronauts of Apollo 11.

Particles of lunar dust can lead to bronchitis and cancer, according to a study published last year by the American Geophysical Union in GeoHealth examining the impact of lunar dust or similar substances.

Fortunately though, Young said there were 120 protective layers on the suit. Lunar dust trapped below the surface layer would have had no impact on the astronauts.

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Based on research on the suits' repairs, they concluded the gloves' spotting must have come from the same process. And that makes sense, Young said.

"The astronauts decided after they were training in the suits that they wanted to take the suits most familiar to them up to space," she said.

"I think originally people thought the training suit would be the backup but because it was already worn in that was the one they wanted to use."

Newer suits were brought into space as the backup instead. And the older originals needed repairs before seeing space.

"Zippers were being fixed all the way up to the flight– up until two weeks before the flight itself," Young said.

Young said that they don't have any plans to continue looking into the matter. The mystery of the spots is considered solved.

Follow Morgan Hines on Twitter: @MorganEmHines.

This article originally appeared on USA TODAY: Apollo 11: Neil Armstrong's moon landing gloves had mystery spots