Today we are again walking around the Tranquility Base, a small area in the Sea of Tranquility where Apollo 11 landed and where astronauts first set foot on the lunar surface. They walked on the moon and flew away, and they left us photographs. What can interest us in the photographs? Yes all! But today we will be especially interested in the flag. The one who either flutters from the wind in the pavilion, or only pretends.
Buzz Aldrin next to the flag, photo AS11-40-5874 (via Apollo Lunar Surface Journal, ALSJ). Is the flag flying?
The flag looks really suspicious - it seems like waves are going along it. Perhaps a door was opened in the pavilion, and a stream of fresh air from the Nevada desert made the flag flutter in the wind?
The flag is disassembled and the case in which it was placed.
We have heard many amazing stories about the construction of this flag, we will not repeat them. Let's briefly describe how it actually happened. The flag was nylon, measuring approximately 1.5 x 0.9 meters (5 x 3 feet). It was bought by catalog for $ 5.50 from a certified retailer near the Space Center near Houston. The manufacturer is not known exactly as the tags have been removed, but it is assumed that the flag was manufactured by Annin & Co. The flagpole consisted of two parts. The lower one should be driven into the lunar soil, the upper one was inserted into it. A sliding telescopic crossbar with a flag was attached to the flagpole with a special loop with a lock, which held it in a horizontal position. During the flight, all parts were in a protective case, which was attached to the ladder of the lunar module. More details can be found on the ALSJ website.
Thus, the flag was not made of foil, was not reinforced with a net, and could be perfectly flown if blown on it properly.
So what about the flag in the photos? Fortunately, we have several images of the Apollo 11 flag, and we can look at it from different angles (and even from the window of the lunar module).
View of the flag from different sides, images AS11-40-5874, AS11-40-5885, AS11-40-5885, AS11-40-5948, AS11-40-5949, AS11-37-5473.
Promotional video:
The folds of the flag appear to look similar in different shots. Maybe he doesn't wobble after all? But how do you know for sure?
Let's select a clearly visible corner on the fold of the flag and mark it with benchmark A in image AS11-40-5885 (extra details have been removed from the screenshot so as not to clutter the landscape). The line of sight from the corresponding point of view goes to this benchmark, now we will see it from the other side.
Benchmark A at the edge of the flag, as seen from the shooting point of frame AS11-40-5885.
Let's move on to frame AS11-40-5905.
The line of sight from the shooting point of frame AS11-40-5885 passes exactly through the same corner of the crease in image AS11-40-5905.
The orange line is the line of sight from the shooting point of the AS11-40-5885 frame. Here's the news! This ray goes exactly through that very corner. We can even put the same benchmark A at this point. This means that the corner of the flag has not shifted during the period of time when both pictures were taken. Obviously, they could not take pictures at the same time: the position of the camera for the picture AS11-40-5885 can be seen from the shooting point AS11-40-5905, and the camera is not there (next to us we see several other cameras in a circle, they correspond to the positions of the camera when shooting a panorama No. 2; photo AS11-40-5885 - part of this panorama).
Let's move away. We should now see two lines of sight corresponding to cameras AS11-40-5885 and AS11-40-5905. Well, where will they converge?
The line of sight from the AS11-40-5885 and AS11-40-5905 points of view converge at the same point on the flag captured in the AS11-40-5949 image.
Although it is less visible from a distance, both lines of sight, undoubtedly, converge at the same point. Isn't it magic? Let's look out the window now.
Now three beams point to the same point. Fragment of AS11-37-5516 image taken from the lunar module window.
Although the angle is different, the corner of the flag is still recognizable - and the benchmark A at the point of convergence of three beams already points to it.
We could have taken other images of the flag from other points, but the result will be the same: benchmark A at the intersection of the lines of sight from different points of the survey invariably coincides with the same corner of the flag. Consequently, this corner did not move all the time that the flag got into the photograph from different angles. You can check on other points of the flag - the same result. Hence, the door to the pavilion was tightly closed.
Of course, the author knows other stories with the flags of other expeditions. The Apollo 14 flag waving in the hands of astronauts on a motion picture. The same flag that flew when the astronauts briefly turned on the engines of the reactive control system for a test, and the gas flow reached the banner. Other videos show flags waving as an astronaut passing by hit them. But these are all other stories.
Is the Apollo 11 flag story ending? Not really. We will not see this flag in other positions in the pictures taken with the Hasselblad camera. But the footage shot on 16mm film shortly before departure prepares us for a surprise.
When the astronauts were already in the lunar module, the flag turned treacherously … Collage from the NASA website.
The astronauts have been in the module for a long time, they are preparing for departure and should not go out anymore, and the flag has definitely turned around! Could it be that at the end of the shoot someone decided to ventilate the Nevada desert pavilion? The answer to the riddle was given by Armstrong in a technical report drawn up immediately after the flight. The flagpole could not be driven deep enough into the ground, the ground did not provide sufficient lateral support, the flag strove to tilt. For stability, the flag had to be tilted back a little. Obviously, over time, the ground gave way under the flag, and it turned under its own weight.
From the words of Aldrin, it is also known that at the start of the take-off stage from the Moon, the flag was overturned by a stream of gas from the engine. Orbital imagery confirms Aldrin's words: in orbital photos, neither the flag itself nor its shadow is visible. The shadows of the flags of other expeditions are visible, the Apollo 11 is not. It was the most unstable of the flags, and it fell as the astronauts departed.
Let's finally try on the flag on the moon.
When unfolded, the size of the flag is 1.18 x 0.83 meters.
Wait. The height of the panel seems to correspond. Instead of 90 centimeters, we see 83, but the lower end moves freely on the loop, the flag could wrinkle a little. But why is the flag only 1.19 meters wide instead of one and a half? The answer is well known: the telescopic bar "stuck" and the astronauts were unable to move it completely apart. They reported this at a post-flight conference and in a technical report. Actually, thanks to this, the flag went in waves. In the next flights, the astronauts did not deliberately push the entire crossbar to make the flag look more picturesque. There have been technical overlays with flags and worse: the clamp of the crossbar in the Apollo 12 expedition did not snap into place, and the crossbar with the flag remained hanging almost vertically.
Our new walk on the moon is coming to an end. We will definitely come back here. El Selenita accompanied you on the walk.