Kallistos Vallis
What Kallistos Vallis is
Kallistos Vallis is a vallis — a valley — on Venus, 900 km across, centred at 51.1° S, 21.5° E in the Lada Terra quadrangle. It is the 207th largest named feature on Venus and the 8th largest of its class there.
Where the name comes from
Ancient Greek name for planet Venus. The International Astronomical Union approved the name in 1994, under the theme it applies to every vallis on Venus. Of the 72 features of this class catalogued on Venus, the naming categories run Egypt (3), China (3), India (3), Mayan (2).
What it would take to settle Kallistos Vallis
Venus scores 43 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 51.1° S, 21.5° E.
What this spot has going for it is known ground — 7,201 km from Venera 14 (1982). What works against it is water — same as everywhere else on this world.
Computed from Kallistos Vallis'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 Venus (radiation geometry, earth link). Gravity, pressure, delta-v and distance from the Sun are the same everywhere on Venus 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.
What is next to it
The largest vallis features on Venus
All 72 valles on Venus — mapped together, with the naming theme and the size distribution.