Grildrig is a crater — a circular depression, almost always an impact scar — on Phobos, 2.6 km across, centred at 81.0° N, 165.0° E. It is the 10th largest named feature on Phobos and the 7th largest of its class there.
Name given to Gulliver by the farmer's daughter in the giantsâ country Brobdingnag in Jonathan Swift's novel "Gulliver's Travels." The International Astronomical Union approved the name in 2006, under the theme it applies to every crater on Phobos. Of the 17 features of this class catalogued on Phobos, the naming categories run Ireland (8), American (5), France (1), Germany (1).
Phobos scores 48.7 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 81.0° N, 165.0° E.
What this spot has going for it is ground — mixed ground — a rim, a floor and slopes between them. What works against it is sunlight — 16% of the sunlight the sunniest latitude on Phobos gets.
Computed from Grildrig's catalogued latitude, longitude and feature class — 68% of the model's weight had a basis here, and 3 axes were dropped as not applicable to Phobos (radiation geometry, earth link, known ground). Gravity, pressure, delta-v and distance from the Sun are the same everywhere on Phobos 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.
All 17 craters on Phobos — mapped together, with the naming theme and the size distribution.