HAPS role of in Earth Observation Multi-platform Paradigm for Environmental Monitoring

Environmental monitoring often requires the observation of phenomena at different spatial and temporal scales. For example, to study the anthropic impact on natural ecosystems, it is necessary both to evaluate its effects on a large scale and to detect and recognize the environmental criticalities that, locally, determine these effects. These needs impose tight requirements on data temporal, spatial and spectral resolution that a single aerospace platform can hardly satisfy. Therefore, it is necessary to develop new collaborative paradigms between different platforms to improve their observation capabilities, exploiting interoperability between heterogeneous platforms and sensors. However, even multi-platform approaches, due to the limitations of the individual platforms currently available in terms of revisit time and sensor spatial resolution, cannot fully comply with the requirements imposed by some specific environmental issues at acceptable costs.

In this paper, HAPS (High Altitude Pseudo-Satellite) use is proposed as a tool to overcome these limitations and to extend the applicability of the multi-platform paradigm. 

In environmental monitoring context, one of the main advantages offered by HAPSs consists in the possibility of providing data with higher spatial resolution than satellites, and at lower cost compared to aerial platforms. Moreover, HAPSs offer a larger field of view than UAVs and can provide data types such as fluorescence or hyperspectral ones that, because of sensor weight and cost, rarely could be acquired by UAVs. Finally, HAPS platforms, thanks to their station-keeping capability on a desired area, offer the possibility of having data with a high temporal resolution to monitor the temporal evolution of phenomena at a rate currently not possible with other platforms.

Different HAPS configurations have been proposed, based on aerostatic or aerodynamic forces. CIRA is designing a HAPS that, thanks to its hybrid configuration, is able to generate aerodynamic and aerostatic forces. It could fly at an altitude of 18-20 km, from this altitude range, the field of view has a diameter length of about 600 km. Maintenance and updating of its equipment and payload is also possible because the platform can land and take-off again.

CIRA is also designing the platform payload. The design goal is to define a new wide-area sensor based on visible, thermal, or hyperspectral cameras, with a better resolution than satellites. In this way, it will be possible to detect environmental anomalies in persistence in order to alert the other platforms. A very high focal second-reading sensor will also be used to avoid false-positive alerts.         

In this paper, we will present the main characteristics of HAPS platforms and how they, in synergy with other ones, would lead to considerable advantages in environmental monitoring. In particular, we will discuss the multi-platform paradigm, the current platform limits and their influence on the paradigm effectiveness in the context of environmental monitoring, characteristics of the HAPS platform that CIRA is currently conceptually designing in the context of the OT4clima Project and the main issues relative to its payload design.