Cyufjy

My brother has recently been converted to a Flat Earther and is convinced that something that proves his theory is the moon landings being faked by NASA. I have managed to counter argue the majority of his points, however yesterday he sent me a video which showed the various layers of the Earth’s atmosphere. The thermosphere in particular has temperatures that reach upto around 1500 Celsius. My research shows the majority of the Apollo 11 Spacecraft was made from an aluminium alloy, which has a melting point of 660.03 Celsius so I wondered how did it not melt whilst going through the atmosphere?

I am sorry if this is an obvious question/answer but I haven’t been able to find a good answer and I need something to stop him from going on about it! Thanks to anyone for any help.

Although the temperature at altitude CAN be several thousands of degrees, the atmosphere is so thin it does not transfer heat efficiently. Wikipedia explains it very well -

The highly diluted gas in this layer can reach 2,500 °C (4,530 °F) during the day. Even though the temperature is so high, one would not feel warm in the thermosphere, because it is so near vacuum that there is not enough contact with the few atoms of gas to transfer much heat. A normal thermometer might indicate significantly below 0 °C (32 °F), at least at night, because the energy lost by thermal radiation would exceed the energy acquired from the atmospheric gas by direct contact

https://en.wikipedia.org/wiki/Thermosphere

The high temperatures experienced travelling out of and back into the atmosphere are those of greatest concern, particularly the latter. On ascent they are high but comfortably within the parameters of modern materials because the craft are travelling relatively slowly in the thicker atmosphere and faster when the atmosphere thins/becomes vaccuum. On descent, i.e. re-entry, the shockwave caused by spacecraft colliding with atoms in the air causes the air to compress, which in turn creates heat. It is NOT due to friction. If you want to see the same effect on a smaller scale, take a deflated football and pump it up as fast as you can, the quickly feel the nozzle of your pump. It will be hot, because the compression of air causing heat has transferred to the nozzle.

Flat earth is an unfortunate belief at odds with mountains of evidence. Sorry to hear your brother has fallen for it.

I suspect that even providing evidence will not be sufficient to dissuade him, based on my own experience of flat-earthers.

It's not the temperature that matters, it's the heat transfer.

The density of the atmosphere up in the thermosphere is very very thin. There simply isn't nearly enough mass to transfer any significant amount of heat from the thermosphere to a spacecraft travelling through it.

Spacecraft do need heat protection to survive re-entry, but that is because they're travelling so fast relative to the surrounding medium, not because of the temperature of the tenuous atmosphere that the medium consists of.

As 'SF' mentioned; the capsule was insulated with an ablative cover. You can read about it in NASA's document: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19740007423.pdf

Just a comment:
If you remember, a shuttle (STS 107) was lost over Texas during reentry because some ablative tiles had been knocked off during lift-off. Reentry heat damaged the unprotected structure resulting in the shuttle being torn apart.
As a Grumman employee, I was involved in building an EVA work platform that was designed before the first shuttle flight to be used before reentry. A crew member would use it to inspect and repair any tiles that had been lost during liftoff. We built and tested the platform in the weightless simulator at JSC, but before the first shuttle flight, NASA determined that the tiles would be secure and remain in place during liftoff and flight, so the platform was never flown.