Satellite-Based System for CNS of Suborbital and Hypersonic Flights

Satellites for communications and navigation play a fundamental and unique role in providing the secure and reliable connectivity needed for safety-critical domains, including for high altitude vehicles for which terrestrial systems support are less efficient. The variety of aircrafts developed for this portion of space is wide, and includes aircrafts for suborbital and hypersonic flights which could fly at Mach 25 and at altitudes above 100 km, to transport goods and people. Projects and initiatives aiming at studying higher airspace applications are increasing. However, due to their peculiar characteristics, high speed and required performances, these vehicles are not fully compatible with the capabilities of current terrestrial systems and suffer from problem of RF Link blackouts affecting their communication and navigation avionics. In fact, during a flight at high velocity and high temperature or during a hypersonic reentry flight, the shock heated air generates a weakly ionized plasma layer. Satellite communications and navigation systems in high altitude vehicles will be required to support the most demanding aviation services (e.g. CNS like Controller-Pilot Data Link Communications (CPDLC), Navigation, Surveillance and Tracking, 4D Trajectory based operations) for the long term. This paper is centered on deriving a satellite infrastructure to support the communication needs of hypersonic and suborbital flights, thereby unifying the management of both air traffic and space traffic. Different solutions to overcome the problems that may arise in relation to the plasma blackout are proposed, with particular attention to satellite system performance and reliability in suborbital and hypersonic flights. The preliminary sizing of the space segment demonstrates the feasibility of meeting the requirements identified by the recently defined Concept of Operations (ConOps) for these flights, despite the challenging operational conditions. This analysis can provide a more modernized vision of European Air Traffic Management (ATM) adapted to enable the seamless integration of high-altitude operations, given the different characteristics of the aircraft and their respective operational, safety, and performance requirements. These requirements have been addressed with particular emphasis in the ECHO project (European Concept of Operations for Higher airspace Operations), which has articulated the operational concept for the European context which have guided the construction of the satellite infrastructure capable of ensuring the necessary communication and navigation needs.