Forty years to the day after it was found and collected by Neil Armstrong, a moon rock is helping NASA mark the anniversary of the first lunar landing from onboard a perch that is closer than any Apollo-returned lunar sample has ever come to its original home in decades.

As was learned exclusively by collectSPACE.com, the moon rock was secretly launched aboard a March 2009 space shuttle mission to the International Space Station (ISS), where on Monday night it will be revealed during a NASA 40th anniversary celebration of the Apollo program at the National Air and Space Museum in Washington, DC.

The 21 gram (0.7 oz) moon rock is only the second out of the 842 pounds (382 kg) of lunar samples collected by the Apollo astronauts between 1969 and 1972 to be launched back into space. And though its journey is planned as a round trip - it will return to Earth as it came with a future shuttle mission - the rock's return to space symbolizes in part NASA's current effort to return astronauts to the Moon.

Not quite "Operation Moon Rock" but still a secret

To keep the moon rock's launch a secret, NASA limited the number of people who were in the know, including within the special laboratory where the agency keeps and prepares the moon rocks for scientific study, educational display and the occasional trip into space.

The agency did not however, circumvent its established system for readying items to go to orbit.

"This was not a deeply organized 'Operation Moon Rock' project," explained Bob Jacobs, NASA's acting assistant administrator for public affairs, in an e-mail interview with collectSPACE.com. "It is not unusual for us to manifest items for various education and outreach purposes. We followed the same procedures."

Indeed, as pre-launch photos obtained by collectSPACE.com reveal, the rock was prepared and packaged alongside other supplies heading to the station aboard space shuttle Discovery's STS-119 mission. In one photo, a package of cherry licorice candy intended for a station crew member is lying by the moon rock carrier's side.

Picking a "return sample" to return to space

Although procedures existed to launch items to the space station, the same could not be said for how to prepare - or pick - a moon rock to go back to space.

The idea was first put forward by the few among NASA's public affairs staff who were aware of the project to Dr. Gary Lofgren, a senior planetary scientist and the Lunar Curator at the Lunar Receiving Laboratory at the Johnson Space Center in Houston. Lofgren recounted what his first reactions were of the idea to collectSPACE.com.

"Ooh, that's an interesting idea. I wonder if we should do that? Hmm ... well, that might be good publicity," recalled Lofgren.

It wasn't however, his decision to make.

"We have a charter committee of scientists that reviews all the requests for lunar samples from a scientific point of view. If they don't approve of it, it doesn't happen," he explained. "In the end, they decided to go ahead and do it." Lofgren did choose the rock to be used.