# Assessment Instructions: Problem Set 06 — Giant Planets, Rings, and Satellites

## Inputs to Inspect
Student submission, this problem set, the solution key, the corresponding lecture slides/notes, and the shared
constants in `materials/ASTR320/src/generate_astr320_content.py` where a problem reuses course data.

## Grading Standard
Award credit for correct method and units first, then for the specific numeric result. A student who shows correct
reasoning with a small arithmetic slip should receive most of the available credit; a student with a correct-looking
number but no visible derivation steps should not. Because this is a 300-level quantitative course, full marks require
a genuine derivation (not just formula substitution) wherever the problem set asks for one.

## Problem-Level Criteria
- Problem 1: both the Phobos density and Mars Roche-limit calculations are required, plus a correctly reasoned conclusion about Phobos's fate.
- Problem 2: must correctly attribute the density difference to self-compression, not to a claimed composition difference.
- Problem 3: must specifically invoke resonant trapping/libration, not a vague "gravity holds it there" explanation.
- Problem 4: must connect conductivity increase with depth to magnetic braking specifically.
- Problem 5: must explain why size alone is an insufficient explanation before giving the core-accretion-timing resolution.

## Resubmission Policy
Students may resubmit within one week of receiving feedback. A resubmission must show a corrected derivation, not
only a corrected final number, and should reference the specific feedback comment it addresses. Regrade to a maximum
of 90% of the original point value unless the error was a grading mistake.

## Common Errors to Flag
- Attributing Jupiter/Saturn density differences to composition differences rather than self-compression (Problem 2).
- Using the rigid-body rather than fluid-body Roche-limit formula without justification (Problem 1), inconsistent with Lecture 12's stated preference for the fluid formula for rubble-pile bodies like Phobos.
- Vague, non-mechanistic explanations for ring-arc confinement that do not reference resonance (Problem 3).