The problem is not the energy ... but the weight you need to lift to get that energy airborne. We don't send astronauts in paper aircraft although they are ligh

The problem is not the energy ... but the weight you need to lift to get that energy airborne. We don't send astronauts in paper aircraft although they are light - we put layer. There are some things that you need - you need them and you get them. If you need 3 x everything = you put them in. It is you engineering duty to make them best, lightest, coolest etc ... but you cannot cut corners. If it was up to me though I would just create some of the external parts of the vehicle as a thermocouple and use the fact that one sight is frying on the syn briefly and the other is exposed into the almost absolute zero. That should create some juice. But I suppose there are good reasons they don't do it.