The technique is the same of the Passive Interception, the difference is that the attacker initiates interaction with the space target trying to trigger potential responses (even error messages) by actively sending signals/packets. The scan can be similar to a "brute force" attack, in the sense that the objective is 'guess' the used frequencies and protocols to obtain a reply. This is why authentication is also included here as a mitigation measure (provided that it does not solicit any response to not authenticated signals). On the other hand, since sending telemetry data won't trigger any response due to their nature (even if they are fully compliant with the expected format), are not included here as a subtechniques.