Sunday, 11 October 2015

Could graphene be used for super light space craft heat shields?

Last night I was watching an interesting video about a self-made billionaire who is spending 99% of his acquired fortune on funding innovation development to tackle energy, water and health issues. I'd not come across Manoj Bhargava or Billions in Change before, and some of the ideas seem a bit "out there", although if they work out then he's producing some badly needed solutions to world problems.

One of the ideas he's funding is a clean energy concept of bringing up heat from deep in the earth to drive electricity generation without using fossil fuels.  Geothermal energy has of course been done for years - Iceland gets most of its power that way.  However the new twist that Manoj and his engineers and inventors have is to use graphene to shift the heat from deep down below to the surface.

Graphene is the atom thick version of carbon that is the new wonder material for all sorts of applications. But Manoj claimed in the video that its heat transfer capability is tremendous - so much so that heat applied to one end of a graphene string will travel along to the other end, leaving the middle cool.  I'd not heard of this property before, but a quick Google search threw up this paper in which physicists have shown evidence of this marvellous heat transfer capability.

Of course there's a lot more research, not to mention engineering development, required before graphene heat pipes become a widely available thing.  But it got me wondering: assuming graphene does have this great heat transfer capability, could it be used in spacecraft heat shields? In effect I'm wondering if it would be possible to wrap a reentry capsule in a graphene matrix made of graphene strings, with one end of each string at the bottom and the other at the top.  As the heat shield warmed up, the heat from the bottom would be conducted over the sides of the capsule and then radiated from the top at the other end of the graphene strings?

I've not heard of graphene being considered for this application before, but then I'm not intimately involved in spacecraft design.  I bet its Elon Musk's radar if it is a possibility (everything is on Elon's radar!)