An example system includes a ground station, as aerial vehicle, a tether, a probe, and a control system. The tether includes a core having a strength, member as well as an electrical conductor that is wound around the core. The probe is attached to the strength member so that the probe is able to measure an electrical property of at least a portion of the strength member. The control system is configured to measure the electrical property along the strength member at a predetermined measurement rate and also determine that the electrical property is outside a predetermined range. Based on the electrical property, damage to the tether core can be assessed.