# Can a space vehicle 100 miles high re-enter without a heat sheild?

**URL:** <https://boards.straightdope.com/t/can-a-space-vehicle-100-miles-high-re-enter-without-a-heat-sheild/567662>\
**Category:** Factual Questions\
**Created:** [January 15, 2011, 12:56am UTC](https://boards.straightdope.com/t/can-a-space-vehicle-100-miles-high-re-enter-without-a-heat-sheild/567662 "2011-01-15T00:56:42Z")\
**Posts on this page:** 4\
**Page:** 2

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**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\
**Post date:** [January 15, 2011, 5:37pm UTC](https://boards.straightdope.com/t/can-a-space-vehicle-100-miles-high-re-enter-without-a-heat-sheild/567662/21 "2011-01-15T17:37:14Z")

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> [@Stranger\_On\_A\_Train](#):
>
> Yes, I understand many people–including technically trained people in fields outside of aerothermal dynamics–refer to such heating as due to “friction”

Yeah, so relax. You knew what we were inferring.

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**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\
**Post date:** [January 15, 2011, 5:49pm UTC](https://boards.straightdope.com/t/can-a-space-vehicle-100-miles-high-re-enter-without-a-heat-sheild/567662/22 "2011-01-15T17:49:26Z")

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> [@Bryan\_Ekers](#):
>
> Yeah, so relax. You knew what we were inferring.

Yes, but the terminology being used was wrong; not just in a semantic context, but literally inaccurate, referring to a particular set of mechanisms (work done on shear layers with or at the boundary of a fluid) that play only a small and often insignificant role in aerodynamic heating by reentry vehicles, versus work done on compression of a fluid via normal forces. They are two very distinct mechanism that should not be conflated even in popular non-technical representation of the phenomena.

Stranger

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**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\
**Post date:** [January 15, 2011, 5:55pm UTC](https://boards.straightdope.com/t/can-a-space-vehicle-100-miles-high-re-enter-without-a-heat-sheild/567662/23 "2011-01-15T17:55:08Z")

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Well, that and I was telling a joke by using “infer” in a common but incorrect manner.

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**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\
**Post date:** [January 15, 2011, 6:25pm UTC](https://boards.straightdope.com/t/can-a-space-vehicle-100-miles-high-re-enter-without-a-heat-sheild/567662/24 "2011-01-15T18:25:03Z")

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Personally, I generally use “friction” as an umbrella term to refer to any dissipative, entropy-increasing force, of which compressive heating would be one. And it’s certainly incorrect to say that “friction” is always, in a technical context, a shear force at a boundary between materials, since there’s also things like “dynamical friction”, which occurs without anything that would normally be called contact at all.

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