Hydrogen ISP is still king by a significant margin, but ISP isn’t the whole story – hydrogen comes with additional tank weight (due to lower density) and storage issues (pesky molecular size…). So that trade-off for ISP only really makes sense for an upper stage like Centaur. I’m not sure it makes sense for New Shepherd even…
Special exception maybe for aviation and rocketry. But even then, methane (if made using green energy and the Sebatier process).
You can get comparable isp with methalox engines without any of the weight required to keep the hydrogen inside the rocket, right?
Hydrogen ISP is still king by a significant margin, but ISP isn’t the whole story – hydrogen comes with additional tank weight (due to lower density) and storage issues (pesky molecular size…). So that trade-off for ISP only really makes sense for an upper stage like Centaur. I’m not sure it makes sense for New Shepherd even…