“So there was quite a bit of interesting photography of the Moon. We had these photographic sites, we had to impress upon them the importance of when to look at them to get the right shadow [to take a good photo].
“NASA engineers called these targets of opportunity, meaning they didn’t have to do it, but if they had an opportunity, they should go ahead and do it.”
Professor El-Baz recalled a fond memory of Armstrong, who made a dash just before he was supposed to leave the lunar surface to snap one of these targets.
He added: “They did very well, actually. Neil Armstrong, in particular, was very meticulous about it, we were always impressed.
“The very last thing that he did – after the mission was done and they collected all the material and started putting it back into the spacecraft and Buzz Aldrin started driving – was remember something important.
“The geologists had told him that we needed to know the thickness of the soil layer of the surface of the Moon.
“You can only see this if you look at the crater and photograph the rim and see how far you have to go down before you see solid rock.
“Anything on top of the solid rock would be the soil layer.”
Professor El-Baz explained why the photographs were crucial at the time, and still could be pivotal in future space missions.
He continued: “Neil remembered that before he finished and before he got into the spacecraft to leave, he ran – very fast – west towards a crater he saw from the distance that would be good to do this with.
“He stood on one side, looked at it, took the picture, turned around and ran back – but it was a fabulous picture and very important for us.