Gwern
What Gwern is
Gwern is a crater — a circular depression, almost always an impact scar — on Europa, 22.2 km across, centred at 9.1° N, 15.5° E. It is the 93rd largest named feature on Europa and the 6th largest of its class there.
Where the name comes from
Son of Branwen in Celtic mythology. The International Astronomical Union approved the name in 2006, under the theme it applies to every crater on Europa. Of the 41 features of this class catalogued on Europa, the naming categories run Celtic (30), Ireland (10), Greek (1).
What it would take to settle Gwern
Europa scores 60.9 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 9.1° N, 15.5° E.
What this spot has going for it is sunlight — 99% of the sunlight the sunniest latitude on Europa gets. What works against it is temperature — about -153 °C mean at this latitude.
Computed from Gwern's catalogued latitude, longitude and feature class — 84% of the model's weight had a basis here, and 2 axes were dropped as not applicable to Europa (earth link, known ground). Gravity, pressure, delta-v and distance from the Sun are the same everywhere on Europa 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 crater features on Europa
All 41 craters on Europa — mapped together, with the naming theme and the size distribution.