A tough exterior of heat-dissipating material is generally used for reentry modules. I am wondering if there have been any attempts or experiments at using liquid cooling systems as thermal protection during reentry. And if not, why? Too costly and complex?

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    $\begingroup$ Why use a heavy active solution, when a passive one will do? $\endgroup$ Aug 25, 2014 at 11:56
  • $\begingroup$ I agree that it's not "smart", I just am curious if the ideas have been explored $\endgroup$
    – Stu
    Aug 25, 2014 at 12:58
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    $\begingroup$ Let us assume that you were to actively cool the surface of the craft with liquid or gas. Where would you now put the radiator to cool the fluid? Active cooling still needs to radiate heat. $\endgroup$
    – dotancohen
    Sep 1, 2014 at 12:22
  • $\begingroup$ @dotancohen the proposed examples I have heard of this, which are mostly from the days before many real space vehicles were developed, used open loop cooling. $\endgroup$
    – ikrase
    Jan 29, 2020 at 9:58

1 Answer 1


Main problems

  1. Would be cost-effective only for reusable craft, mostly hypersonic spaceplanes (see NASP).
  2. Active cooling may fail spectacularly => Mission loss.
  3. It is hard to achieve required number of cycles before refurbishment due to thermal stress.
  4. Too heavy! -> Cannot compete with ablative/heat sink TPS for non-reusable craft.

TPS Concepts

Timeline for Active TPS

Active TPS development

Source: Current Technology for Thermal Protection Systems, 1993.


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