The NanoROLD project in the frame of the AeroClouds programme

The article reports on the study results of the NanoROLD (Nano Radio Optical Lightning Detector) project, which was proposed for inclusion in action line 3 (Climatic aspects of clouds and precipitation) of the AeroClouds Programme planned around the year 2004 by the MIUR (Ministry of Education, University and Research). After a short review of the AeroClouds objectives and the lightning geolocation requirements, the article reviews the location accuracies achievable with both single and multiple satellite system configurations, and compares the two approaches from performance and complexity viewpoints. The feasibility of radio frequency (RF) detection of electrical discharges is dealt with first, to demonstrate the feasibility of a high accuracy lightning geolocation mission by means of microsatellites, while the assessment of optical instruments is deferred to a later study phase. The final comparison is then restricted to two candidates: a three-satellite formation exploiting time-of-arrival (TOA) principles; and a single satellite implementing a three-arm radiofrequency interferometer. The expected greater costs of a three-satellite constellation in formation flight are offset by the greater complexity and criticality of the interferometer system based on a single satellite and by its poorer performance in terms of lightning geolocation accuracy. However, for an experimental, fund-limited programme, a demonstration mission based on a single satellite could be more appropriate and an initial baseline design is also provided in the article.