I'd like to share the story of a personal interaction I had Alan Bean, Apollo Moon-walker and artist. In 2010, I needed more information about something Alan had seen when he was on the Moon. I was researching how rocket exhaust blows soil and dust during lunar landings. /1
2/ The best information on this topic was from Apollo 12, when Pete Conrad and Alan Bean landed their Lunar Module 160 m away from the old Surveyor 3 ("S3") spacecraft. S3 had sat on the Moon deactivated for about 2 and a half years exposed to the lunar environment.
3/ The Ap12 mission was planned to land near S3 to (1) demonstrate precision landing and (2) to cut pieces off S3 and bring them back to Earth to see how the lunar environment degrades various types of materials and spacecraft parts.
4/ They planned to land the Ap12 Lunar Module ("LM") about 500 ft away from S3 to minimize the amount of sandblasting that would occur to the S3 as the LM's big descent engine blew the lunar soil and dust. It turns out 500 ft wasn't nearly enough!
5/ Ap12 was also unique among the Apollo mission for how close they landed near the Moon's terminator line, which is the line that separates day and night on the surface. They landed where the sun was only 5 degrees above the horizon, so the local time was barely after sunrise.
6/ It turns out thus had a huge effect on the landing operations. At least, that is my own theory about what happened. You see, Ap12 blew more dust with its descent engine than the other 5 lunar landings. (Or, maybe it just it _looked_ that way.) It was so bad that...
7/ ...that they couldn't see the ground under all that dust. Pete Conrad later said he couldn't tell if there was a boulder or a crater in a bad spot, so he just took the risk and landed in the blind. There was a real risk of death, but they didn't come so close just to abort.
8/ You can find the Ap12 landing video online (YouTube?) and you can hear Alan Bean's distinctive voice encouraging Pete to just go ahead and put it down in the final seconds. Remember Pete's words about landing blind as you listen to Alan encouraging him.
9/ It was never explained why Ap12 blew so much dust compared to the other missions, but I hypothesized that it didn't really. Instead the dust just _looked_ more opaque because the sun was so close to the horizon its light traveled thru twice the dust to illuminate the surface.
10/ In any case, a LOT of dust was blown. My team later estimated after many year's research that well over a ton of soil was blown by each landing. It was blown at 400 m/s up to 3 km/s. Larger particles went slower. Fine dust flew faster & farther in the lunar vacuum,
11/ Moon junkies might recognize the significance of that last number: 3 km/s is higher than lunar escape velocity! That means a dust ring may have been blown completely off the Moon into solar orbit with each Moon landing. More importantly, there is no safe distance on the Moon.
12/ What I mean is that for every distance away from an LM landing site, there were dust particles that blew to that distance. At very long distances the amount of impacting dust became extremely tiny, but even on the back side of the Moon you might get hit by some ejected dust.
13/ Alan Bean's mission gave us an absolutely unique chance to really measure this blowing dust. After landing, Pete and Alan walked over to the S3 spacecraft and cut off pieces that had been subjected to the intense sandblasting of their LM landing just 160 m away.
14/ As Alan rounded the large "Surveyor Crater" and approached the S3 spacecraft he said to mission control via radio, "I thought you said this spacecraft is supposed to be white." (Not exact quote - I'm going from memory here.) Mission Control asked "Why? What color is it?"
15/ Alan said "It's brown!" This set off a lot of discussion back here on Earth. What did the lunar environment do to that spacecraft to change it from white to brown??? The leading theory was that radiation changed the chemistry of the paint. That theory held for 40 years.
16/ Around me 2008 I traveled to Houston and officially checked out all the white painted pieces that had been cut off the S3 spacecraft and returned to Earth by Ap12. I had to keep them in a special safe with lots of security since they are truly priceless national treasures.
17/ We analyzed those pieces using many modern methods that were not available 40 years earlier, right after the Apollo program, when earlier researchers had tried to study them. We used Scanning Electron Microscopes, laser scanners, X-ray photoionization spectroscopy,...
18/ ...and electron dispersive spectroscopy. We discovered the paint's surface was penetrated by sand-sized (100 micron) lunar soil particles travelling about 400 m/s. Each one made a pinhole in the paint, and we could see the soil particle lying in the bottom of each tiny hole.
19/ Give me a moment to see if I can download the picture of this...
20/ Aha! I found it and just now did some contrast enhancing. (Modern technology is amazing.) This was cut off off Surveyor 3 by Alan Bean and Pete Conrad. It is aluminum with white paint. You can see a bolt hole where a washer covered & protected the paint so it is still white. 
21/ Now there are some SUPER interesting things we discovered in this, and it drove is to call Alan Bean by phone 40 years after his mission to discuss what it all means. For one, consider that semi-circular shadow next to the bolt hole...
22/ That is the shadow of the head of the bolt that used to be in that hole. The funny thing is that the bolt is now gone but its shadow is still there. Is it a ghost shadow? No. It is a sandblasted shadow formed by the intense spray of dust when Alan and Pete landed 160 m away.
23/ Everwhere that got sandblasted got turned lighter in color. Everywhere that was protected by shadowing stayed darker. That's the brown color Alan reported seeing on the Moon. Earlier researchers triangulated these shadows and proved that they point back to the Apollo LM.
24/ What my team did in 2010 is prove that the brown color was not really the result of radiation as prior researchers believed. Instead, we proved the shadows are actually MADE out of lunar dust. All the brown color is lunar dust that was already on S3 before the Ap12 arrived.
25/ The sandblasting spray of lunar dust from the Apollo landing actually removed more dust from S3 than it put onto S3. That discovery was shocking. We analyzed the chemistry of that dust and we discovered it had different minerals on the east versus west sides of the Surveyor.
26/ This story got overly long, so I'll get to the best part. We were amazed by all the mysteries of the dust on the Surveyor, and we even wrote a paper in 2010 where we called it a mystery. researchgate.net/publication/23…
27/ We scoured the historical records of the mission for any more clues. We eventaully realized we needed to talk to Alan Bean himself to understand exactly what he saw as he walked toward S3 on the Moon and exclaimed to Houston about its brown color. So a friend set up the call.
28/ Alan was extremely nice. He had a great sense of humor and seemed to truly enjoy talking about his observations on the Moon. Of course his memories of some details had faded, but he was able to confirm the main things about what he saw, which we needed confirmed.
29/ We talked casually without any rush for about an hour. After we had finished the technical discussion he wanted to tell us about his art. He told us that he had set up a size-scaled diarama of the Apollo 12 landing site in his home, filling up an entire room.
30/ He cares about accuracy in his paintings so he takes precise measurements from the diarama to make sure all the perspective views at just right. He told us about the use of colors in his paintings. He said most people see only gray on the Moon, but he saw it full of color.
31/ His paintings show all colors in the lunar soil. (I found it interesting that he was the one who reported the color of the Surveyor spacecraft. He was indeed tuned into colors while on the Moon's surface.) He also told us about the texturing of his paintings.
32/ He uses boots and Apollo soil tools like the ones he used on the Moon to impress surface texture into the paint. He continued talking avout his art with passion for about 10 minutes. Then he wound down and finished by saying this, which I will never forget...
33/ He said he is not an engineer anymore, but an artist, and he takes his art extremely seriously. He said he has all these paintings in his head which he needed to get onto canvas before he died. He was devoted to telling the story of the Apollo program before it was too late.
34/ He knew he had limited time left in this world, and the world needs to see the Apollo missions through the eyes of an artist. He ended with, "I can't allow myself to get dragged back into engineering. I have to focus on art. So Don't...Ever...Call. Me...Again."
Pow.
Pow.
35/ Honestly it hurt when he said that. Did I make a mistake contacting him? Did I steal irreplaceable art from the world by taking an hour of his time? The tone of the conversation until that moment tells me he _wanted_ to talk with us. But only just that once, and never again.
36/ What I love about Alan Bean is first that he landed in dust so opaque neither he nor his commander could see whether they would survive the event, yet with a voice full of enthusiasm and not hint of fear he told Pete to go on down. The world needed them to land.
36/ Second, that when walking in a world of never-ending gray he saw only color. Reds, blues, yellows, purples, greens...and the brown spacecraft that was supposed to be white. Some saw it as an engineering question of blowing dust. Alan saw it as a question of color.
37/ Every color in Alan's heart was there on the Moon, in its craters and rocks and hills, because a human was walking in that world -- an artist -- and wherever humans go there is color. All the color.
38/ And third, I will always love Alan because he told me to never call him again. Truly. What he was doing in art was more important than what I was doing in science and engineering, and he knew it, and he needed us in NASA to know it, too, and to respect it.
39/ There will always be more time to land spacecraft on the Moon to study how they blow dust. There will never be another time when the first set of humans that walked on another world turns the wonderment of that experience into art. I love Alan that he saw this & defended it.
40/40 My hope is that every painting he had in his heart made it onto his canvas before time ran out. Though I won't walk on the Moon, I hope I can see colors like Alan did everywhere I go. And I hope we'll share his passion & focus to keep painting--in our own ways--to the end.
