An asteroid mitigation demonstration mission is gaining interest among the planetary defense community to better understand the challenges and the dynamics of a small solar system body (SSSB) impact scenario. The Kinetic Impactor (KI) deflection technique, considered the most mature and cost effective approach for deflecting SSSBs, gained more credibility following the numerous studies performed (Don Quijote, NEOShield-2, preparations for DART mission,...) and last but not least the successful targeting of the Deep Impact (DI) spacecraft into comet 9P/Tempel 1. A dual-launch concept Asteroid Impact Deflection Assessment (AIDA) with KI (DART) and an Explorer spacecraft (AIM) is currently under study by the ESA and NASA. While one of the more mature deflection options, there are still a significant number of poorly constrained aspects of the KI deflection technique. Of particular interest are the complex ejecta cloud dynamics that can have a considerable impact on the deflection efficiency - better known as the momentum enhancement effect. Understanding the beta factor is considered paramount as it bears the potential of overall mission reduction cost and is inherently linked to SSSB geotechnical properties. Therefore, measuring this enhancement effect will be one of the top-level scientific requirements for future demonstration missions. This paper discusses the aspects of beta estimation techniques for a mitigation demonstration mission and reveals (1) the geometric considerations of the impact trajectory and the near-Earth object (SSSB) heliocentric orbit, (2) the requirements on the impact spacecraft navigation accuracies and (3) the prerequisites on the SSSB characterisation. An illustrative scenario and results are presented where the work concludes with considerations for an asteroid mitigation demonstration mission design aiming at measuring the beta-factor.