Ares 13

Spaceflight History / No Shortage Of Dreams recalls his concerns about aborting a Hohmann mission, here to the Mars system. A. A. VanderVeen ran the maths: three phases.

You might be back on Earth in a few weeks if you abort days 1-60. Past that, you swing by the Sun on a 0.7ish AU perihelion opposition-class fryby. Days 180 through 270, matters get a bit better and you can hit up Earth as before.

For "Earth" read "inner planet A" and for "Mars", read "planet past 1 AU in A's units". The same basic three-phase maths apply for Deimos-to-Ceres or for Venus-to-almost-anywhere: it's just the length of the intervals as will change. If the main base is outward and the problem is inward, the calculus will differ. The maths for either must await another day and, mayhap, another laptop.

Ultimately the Equations remain Cold. Where Apollo 13 was a story of heroism and engineering; Ares 13 stands to be a horrific tragedy.

This is why we need Castles on cycler-orbits; because then there's a ghost of a chance someone might come to you with rescue-supplies. A set of bases along Venus and SVL4-5 should also help for supplying Ares 13.