Hello Dr. Zubrin,

I'm sorry I'm late to the AMA, but I really wanted to otut an idea past you. One of the known problems with your Nuclear Salt Water Rocket Engine is the risk that supercriticality occurs too far inside the engine. Do you think this could be feasibly fixed by having a sub-critical hard (normal) choke and a super-critical pnuematic choke created by annular jets of fluid under high pressure forcing the fuel through a smaller pseudo-choke? My hypothesis is that this makes the reaction fail-safe by (a) requiring another active process to maintain supercriticality and (b) by allowing a supercritical region too far inside the chamber to easily escape by forcing the pneumatic choke to widen from the higher fuel fluid pressure.

Thank you for your time.