[anthony_doan]

You can't get faster engine without having slower one first.

How do they even know what to improve upon without building it and experiment with it?

Also simulation is not a replacement for real world testing. They should launch stuff into space to figure out if it works and their simulation is making the correct assumptions.

Also I'd imagine these launches are sending back valuable data that they can use to make adjustment and improvement for future engines.

[macintux]

Based on what we seem to be learning about how the body responds to the hostile environment of space, it seems reasonable to think we should wait for the faster engines. Send drones if you must.