— While July 20, 1969 is likely the date that most people associate with the first man on the Moon — it being the day (by U.S. time zones, at least) that Neil Armstrong first set foot on the lunar surface — it was this day 40 years ago, September 9, that many if not most have marked down on their souvenir of the event.

That is because on this day in 1969, with Armstrong and his Apollo 11 crew mates Buzz Aldrin and Michael Collins present in Washington, DC, did the United States Post Office Department (which just under a year later became what is now the U.S. Postal Service) release the 10-cent First Man on the Moon airmail stamp, and with it came a flood of public requests for "First Day Covers", envelopes postmarked in the city and for the date where the stamp was first introduced.

Nearly 9 million of the covers were processed, surpassing any other stamp release to that date and even beating the 1993 Elvis stamp, the most popular U.S. commemorative stamp of all time based on the number saved, which had three million fewer covers requested.

Beyond the covers though, the stamps themselves were special. The largest stamp released up to that day, it was produced using an engraved die that was carried to the Moon on-board the Apollo 11 spacecraft.

The stamp's designer, Paul Calle, had previously created the art for the 1967 U.S. stamp that honored the Gemini program. One of the first eight artists to be selected for the NASA Art Program in 1962, Calle was present for the Apollo 11 astronauts' last few hours before they departed for the Moon, sketching Armstrong, Aldrin and Collins as they donned their spacesuits.

To mark the 40th anniversary of the 10-cent First Man on the Moon airmail stamp, collectSPACE spoke with Calle and his son Chris, who designed the 1989 $2.40 Apollo 11 20th Anniversary Priority Mail stamp and jointly with his father, the $9.95 and 29 cent Express Mail stamps for the 1994 25th anniversary of the mission.

Forty years later, what has it meant to you to design the stamp that honored the first lunar landing?

Designing the First Man on the Moon stamp in 1969 was a great honor and especially significant because of my involvement in the NASA Fine Art Program. The design process was kept a secret until not long before the Apollo 11 launch I believe. I had been with the crew during their activities readying for the launch the morning of July 16, 1969, sketching their breakfast and suiting up and knowing that the engraved plates were traveling to the moon with the astronauts was exciting.

I remember when Armstrong stepped foot on the moon, my 8 year old son at the time Chris kept asking, "Where's the stamp? Where's the stamp!?"

If you were designing that stamp again today, would you change anything?

I went through so many different concept ideas for the stamp and completed sketch after sketch, by the time we chose final sketches we were all confident that the "First Step on the Moon" approach was the correct imagery. The final paintings encompassed all the key elements — the first man stepping on the Moon and our planet Earth.

From an artistic point of view, knowing now that the lunar module had more gold on the landing gear and pads, I would have painted those in gold.

For the 40th anniversary, we understand you have produced a limited edition print of the stamp artwork. Was it based on the original art you produced for the U.S. Postal Service? Where is the original?

Yes, the limited edition art print is of the original painting I did for the stamp. I believe the original is in the archives of the Postal Service or at the National Postal Museum in Washington. We own many of the rough thumbnail and more completed sketches and Chris has posted many of these on our website.

How many of the original stamps do you own today? Do you have a stacks of uncut sheets?

We certainly own a few dozen sheets. Chris comes upon them regularly and uses them for event covers like ones he produced for the 40th anniversary.

Chris actually collects the 1969 10 cent First Man on the Moon First Day Covers and has quite a collection. Many signed by the stamp designer!

You and Chris also designed stamps for 20th and 25th anniversaries of Apollo 11. Did you the Postal Service ever contact you about a possible stamp for the 40th anniversary?

We were not approached to design a 40th anniversary stamp. We still hold out hope that they might see the wisdom of commisioning us now to work on designing the stamp for the 50th anniversary ten years from now.

It has been nearly a decade since the U.S. has issued a space exploration themed stamp. Why do you think this is?

Like the collectors interested in space stamps, we are amazed that no recent stamps with a space theme have been issued. Space has always been a wonderful and popular topical to collect in philately and we would like to think the Postal Service would understand that fact and issue stamps with space themes on a regular basis.

The First Man on the Moon limited edition giclee art print is available through the Calle Space Art website.