J.3.3 Damage assessment

Here a brief general overview of damage assessment criteria and procedures is given. A more detailed and extensive description can be found in [RD.91]

For each individual project the damage assessment is tailored according to the specific conditions and requirements (e.g. orbit, shielding, damage criteria, and required reliability).

Any damage assessment depends to a large extend on the relevant failure criteria. Possible failure criteria include:

• cratering (sensor degradation, window blinding, surface erosion);

• larger craters (sealing problems, short circuits on solar arrays);

• impact generated plasma (interference, discharge triggering);

• impulse transfer (attitude problems);

• spallation from inner wall (equipment damage, crew injury);

• wall penetration (damage, injury, loss of liquid or air);

• burst, rupture (pressurized parts);

• structural damage.

For a quantitative damage and risk assessment so called damage or design equations for the given shielding configuration are needed. They give shielding thresholds or hole sizes for given impacting particle parameters and failure mode.

Sometimes scaled effective thicknesses in combination with known damage equations can be used for a first assessment.

For impact damage and risk assessments secondary ejecta can be important as well. The total mass of the ejected particles can exceed the mass of the primary impactor by orders of magnitude. Secondary particles are typically ejected within a cone around the impact direction. Their velocities are typically below 2 km s^-1.