Odd spacecraft question

[Shaw]

Why are the Apollo and Orion command modules covered in a mylar-like film? And why wasn't it applied on the first Orion flight or the SkyLab missions?

At first I thought it might have something to do with the Moon missions, but it was included on Apollo 9 and (I think) Apollo 7 (both Earth orbital missions).

 

[K2Pete]

I read that it's Thermal protection ... and I searched and found this ...

 

https://space.stackexchange.com/questions/6556/what-was-mylar-used-for-on-the-apollo-command-module-space-craft-why-is-it-gold

 

From the same link ... 

Actually, it's Kapton (polyimide), not Mylar (polyethylene terephthalate) or multi-layer insulation. Kapton and Mylar are both DuPont trademarks for polymer films, so perhaps it is easy to get them confused.

According to the Apollo Experience Report: Thermal Protection Subsystem,

The thermal control requirements for the spacecraft in outer space necessitates a relatively low thermal absorptance-to-emittance ratio of 0.4 for the surface of the CM. This low ratio is achieved with a pressure-sensitive Kapton polyimide tape that is coated with aluminum and oxidized silicon monoxide and that is applied over the entire external surface of the ablator.

 

So it's for the extreme conditions out of Earth orbit as well as for re-entry.

And IIRC, the Skylab CM wasn't entirely covered in this tape, because the CM was facing the Sun in one particular attitude, which required more heat shielding than the Kapton could provide ...

 

Pete

[Hotdog]

Orion EFT-1 only needed tiles since it was an Earth orbital mission. The kapton tape is needed for lunar and deep space mission due to the faster speeds and more friction the spacecraft will experience.

[Shaw]

Thanks for the replies!