Well, Armstrong and Aldrin would play all kinds of practical jokes, and Collins would just express frustrated annoyance…
On the contrary, there are flat applications. A few of the GEOs I worked on, had a single layer installed on the “top” deck of the spacecraft. It was taunt as a drum; they were mounted like volleyball net on the non-solar panel sides. During vibration tests, you’d watch film transition through several modes (1st order, second order, etc…).
I’m pretty sure mine was different. Thinking back it also had a command module. There was a base (with craters and stuff) that the LEM sat on, and it had an arm that held the command module above it. There were also a couple of astronauts and an american flag that stood on the base. Wow, I was really little when I had this. My dad and big brother had to help me put it together.
It doesn’t serve any purpose. The wrinkling is an artifact of how the material is applied, i.e. it is wrapped, bonded, or otherwise attached to irregular surfaces (like the LM) that it is not feasible to apply a solid reflecting layer, just as when you wrap foil around a plate of food it is not smooth. The wrinkling makes it slightly less efficient (as some radiation is re-radiated onto adjacent surfaces) but not dramatically so, and for protection against incident radiation it is superior to cork, RTV, and other forms of passive thermal protection. The wrinkling is not necessary to prevent layers from touching, as the scrim between layers that provides tensile strength against thermal stresses also provides thermal separation, and the layers of metal mesh underneath the outer reflective layer are typically coated with plastic to minimize conduction. In some situations, as user_hostile states, the material can be stretched taut, and it is in fact quite tough, but that generally isn’t needed or desired, and could result in undesired acoustics during the boost phase.
MLI is generally just reflective on the outward facing side, and in fact is used to cool (by differential radiation) the vehicle. Although solar heating is sometimes used as a thermal source (using a maneuver called a “barbeque roll” for assuring that volatiles are boiled off before uncovering optics or normalizing thermal stresses before deploying mechanisms), for heating propellant or instruments internal thermal sources are almost always employed to assure positive control.
Also, it is the Apollo Lunar Module (LM, or sometimes ALM). Lunar Excursion Module (LEM) was employed in some trade study documentation but was never the official nomenclature for the Apollo lander. The lander/habitat for the Constellation program was known as the Lunar Surface Access Module (LSAM) despite space journalists and enthusiasts consistently referring to it as the LM, LEM, CLEM, et cetera.
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