Tokoyo Fossa
What Tokoyo Fossa is
Tokoyo Fossa is a fossa — a long, narrow depression — on Ryugu, 0.6 km across, centred at 50.5° S, 166.2° E. It is the 2nd largest named feature on Ryugu and the 1st largest of its class there.
Where the name comes from
Immortal world of Japanese mythology, eternal, timeless land across the sea or undersea kingdom, where the princess Otohime lives in the fairy tale about the fisherman Urashima. The International Astronomical Union approved the name in 2018, under the theme it applies to every fossa on Ryugu.
What it would take to settle Tokoyo Fossa
Ryugu scores 58.1 as a world. That number is the same for every square metre of it — but sunlight, water, radiation and the ground under your feet are not. This is the same question asked at 50.5° S, 166.2° E.
What this spot has going for it is known ground — 1 km from Hayabusa2 touchdown (2019). What works against it is water — same as everywhere else on this world.
Computed from Tokoyo Fossa's catalogued latitude, longitude and feature class — 74% of the model's weight had a basis here, and 2 axes were dropped as not applicable to Ryugu (radiation geometry, earth link). Gravity, pressure, delta-v and distance from the Sun are the same everywhere on Ryugu and are already counted in the world's own index, not again here.
What this cannot see: elevation. Slope, local shadowing and the polar “peaks of eternal light” — ridge tops near the poles of a barely tilted world that catch sun almost continuously while a crater floor kilometres away never does — need a terrain model this does not have. Where a real mission targets a pole, that is usually why.