sexta-feira, 27 de abril de 2012
MAN WAS IT THE MOON?
Man was it the moon?
Over the last several decades the Moon landings of the late 60s and early 70s have garnered much scrutiny. Some have argued that it would have been physically and technologically impossible to land men on the Moon and return them home. Was it all a hoax? Did NASA fake the Moon missions on a sound stage? I'll discuss the claims of the conspiracy theorists and let you determine for your self if man really landed on the Moon. Did you think of an issue I didn't address? Send me an email and I will be sure to add it.
In most of the photos taken during the lunar landing missions there stars are absent in the background. Why is that? Clearly, in the pictures there is a considerable amount of light from the Sun. Also, the Sun light is reflecting off the lunar surface (more on that later). So, in order to take crisp pictures, the camera needed to be set to take pictures in high light. Using a very high frame rate, and small aperture setting, the camera can not gather enough light from the very dim stars to be seen.
There are many instances of this in Moon landing images. Objects in the shadow of another object, like this image of Buzz Aldrin in the shadow of the Lunar Lander, are clearly visible. How is it possible that we can see him so clearly? The problem is with our assumption that the Sun is the only source of light on the Moon. Now, obviously the Moon does not produce its own light, but it does reflect the Sun's light very well! This is also the reason that you can make out the details on the front of an astronaut's space suit (see image in item 3) in photos where the Sun is behind him. Light is being reflected from the Lunar surface to illuminate it.
There are actually two questions that are commonly asked about this photo, the first was addressed in item 2 above. The second question, is who took this image? It is difficult to see with this small image, but in the reflection of Buzz's visor it is possible to make out Neil Armstrong standing in front of him. But he does not appear to be holding a camera. That is because the cameras were mounted on the chest area of their suits. Armstrong was holding his arm up to his chest to take the picture, which can been seen more easily in larger images.
Well the answer is that its not waving! In images of the American flag on the Moon, the flag appears rippled, as if it is being blown in the wind. But this is actually due to the design of the flag. It was created to have rigid, extendable support pieces on the top and bottom so that the flag would look taut. However, when the astronauts were setting the flag up, the bottom rod was jammed, and would not fully extend. Then, as they were twisting the pole into the ground, the motion caused the ripples we see. On a later mission, astronauts were going to repair the defective rod, but decided they liked the wavy look so left it the way it was.
In some of the photos, shadows for different objects in the images point in different directions. If the Sun is causing the shadows, shouldn't they all point in the same direction? Well, yes and no. They would all point in the same direction if everything was on the same level. This, however was not the case. Because of the uniformly grey terrain of the Moon, it is sometimes difficult to distinguish changes in elevation. However, these changes can influence the apparent direction of shadows for objects in the frame. In this image the shadow of the lander points directly to the right, while the astronauts shadow points down and to the right. This is because the Moons surface is at a slight incline where he is standing.
The Van Allen radiation belts are doughnut shaped regions of space in the Earth's magnetic field that trap very high energy protons and electrons. As a result, some wonder how astronauts could have passed through the belts without being killed by the radiation from these particles. NASA quotes that the radiation would be about 2500 rem per year with almost no shielding. Considering how quickly the astronauts passed through the belts, they only would have been exposed to about 0.05 rem during the trip there and back. However, I have seen some numbers quoted as high as 2 rem during the trip. But even assuming levels that high, the rate at which their bodies could have absorbed the radiation still would have been within safe levels.
During the descent, the lunar lander would have fired its rocket to slow it down. So, why is there no blast crater on the surface of the Moon? The lander had a very power rocket, capable of 10,000 pounds of thrust. But they didn't need to use all 10,000 pounds of thrust to land the module, in fact they needed only about 3,000 pounds. Concentrated all in one place it should have produced a noticeable crater. But there is no air on the Moon, therefore there is no pressure causing the exhaust gas to go straight down onto a concentrated area. It would have spread out over a wide area. If you calculate the pressure on the surface, it would have been only 1.5 pounds of pressure per square inch; not enough to cause a blast crater.
In all of the images and videos of the lunar module landing and taking off, there are no visible flames from the rocket. How is that? Simple, the type of fuel that was used (a mixture of hydrazine and dinitrogen tetroxide) mixes together and ignites instantly, producing a "flame" that is completely transparent. This fuel mixture is still used in some orbiting space craft, and images of those craft clearly show no flames.