Ricerc@Sapienza

In the recent years, an increasing interest towards enhanced and more frequent operations at high altitudes has been demonstrated both by aerospace industry and academics. In particular, many institutions and companies are developing the so-called HAPS (High Altitude Platform Stations, [1] - [3] ), high altitude balloons provided with low-thrust propulsion systems able to maintain their position over a target. These vehicles are provided with power generation systems and are able to perform long-term missions of weeks or even months.

Time Difference of Arrival (TDOA) networks could support spacecraft orbit determination or near-space (launcher and suborbital) vehicle tracking for an increased number of satellite launches and space missions in the near future. The evaluation of the geometry of TDOA networks could involve the dilution of precision (DOP), but this parameter is related to a single position of the target, while the positioning accuracy of the network with targets in the whole celestial vault should be evaluated.

With the increasing number of satellite launches, especially in Low Earth Orbit (LEO), optical tracking can offer a convenient enhancement of tracking precision and availability. Spaceborne active illumination devices, such as LED payloads, can offer a significant improvement to optical observations, extending the observability interval to the whole eclipse time and performing optimized flash sequences for identification, orbit determination, attitude reconstruction or low data rate communication.

Proton and carbon ion beams are used in the clinical practice for external radiotherapy treatments
achieving, for selected indications, promising and superior clinical results with respect to x-ray based
radiotherapy. Other ions, like 4 He have recently been considered as projectiles in particle therapy centres
and might represent a good compromise between the linear energy transfer and the radiobiological
effectiveness of 12 Cion and proton beams, allowing improved tumour control probability and

4rNRdweH The future rise of stratospheric and suborbital aviation shall consider the introduction of innovative surveillance and navigation systems for optimizing integration with the conventional civil aviation flights, while maintaining adequate safety rates of all the planned operations. Currently, commercial and civil aviation vehicles surveillance relies on active systems, i.e. radars, while data fusion among inertial, satellite and radio-based systems is exploited for navigation purposes.