Ok, so as far as I can tell this is just a concept. "Liquid hydrogen" I guess makes for some splashy headlines but I'm doubtful about the practicality. Hydroge

Ok, so as far as I can tell this is just a concept. "Liquid hydrogen" I guess makes for some splashy headlines but I'm doubtful about the practicality. Hydrogen boils at -253C (20K). This is not a trivially achieved and maintained temperature. NASA used this for the Saturn V, which largely explains why the Saturn V is still the most powerful rocket ever flown. To compare: - Liquid hydrogen + liquid oxygen has a specific impulse of 450 - SpaceX's Merlin engine uses RP-1 (kerosene) and liquid oxygen for a specific impulse of 250-300 The demands of the Falcon 9 are lower of course (not exceeding geostationary orbit, for a second ignoring the Falcon Heavy variant) but this affords SpaceX the luxury of using a fuel that is much cheaper to store and use. This goes beyond cold however. Hydrogen atoms are incredibly small (fun fact: helium atoms are smaller). This makes leakage a huge problem. It also gets in between the atoms of whatever storage material you're using (for fusion reactors this problem is called "helium embrittlement"). So do I believe this will turn into something real? Let's just say I have my doubts.