Envisioning the world of 2100

[Byeman]

(I highly recommend MIT's graduate level course on aerospace system design that was entirely devoted to the Space Shuttle).

Don't need to learn it second hand since I had first hand experience with the Shuttle. Additionally, I know many of the lecturers in the course.

 

[Byeman]

The IUS on the Shuttle does use trajectory optimization, with each flight planned with months of simulations to make sure a satellites own RCS fuel won't be overly consumed to correct a residual error due to the inexact final impulse (which is accurate to about 0.5%)

The IUS motors were intentionally undersized so that there never would be overburn. Each IUS stage burn was followed by an IUS RCS burn to make up the shortfall and provide the exact impulse required.

 

[publiusr]

pressure fed engines are even lighter than pump driven engines.

Something like Sea Dragon, but smaller doesn't need a gantry or carrier aircraft, and can pop out of the water like a cork. But Musk was forced off the coast due to range safety, and he probably has had a belly full of at-sea logistics.