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by perihelions
1013 days ago
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There's a lot of loopholes you could plausibly escape through. For one: you could use hybrid atmosphere-breathing engines to get most of the way to low orbit. (Using ambient atmosphere as a reaction mass circumvents the rocket equation). From low orbit, you can switch to electric thrusters with Isp much higher than the engines considered here: it's no longer necessary to have a thrust/weight ratio greater than unity. A hydrogen planet would be particularly easy, since the light molecules would maximize Isp for a (non-combustion) thermal engine. A nuclear scramjet on a Hycaean world would have some truly impressive performance. |
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To explain for all of the non engineers:
On earth scramjets work because airflow enters the front of the engine and the shape of the inlet compresses the gas, fuel is added and burnt, then the exhaust gasses go out the back really fast.
With a nuclear scramjet the fission reaction heats up the middle of the scramjet so air comes in, is compressed then heated so it expands and goes out the back really fast.
That would move you very quickly and efficiently through the dense atmosphere, using almost no fuel, and you do not have to carry much reaction mass.
Then once in space you feed compressed hydrogen into the front of the engine heat it up and send it out the back really fast, just like the nuclear rocket motors that nasa is developing right now.