Skyline S2

Laser Communication Terminal

Skyline S2 is a Laser Communication Terminal (LCT) for the Zephyr High Altitude Pseudo-Satellite (HAPS), a solar powered platform developed by Airbus, operating in the stratosphere. The Skyline S2 LCT will enable a 1Gbit/s inter-Zephyr bi-directional link, spanning distances of up to 100 km. Airbus Netherlands has designed a novel, compact aperture for the terminal. Thanks to this exceptionally small opening through which the laser light passes, Skyline S2 can meet the stringent requirements concerning mass, size and power consumption, while being capable of withstanding the harsh environmental conditions of ambient temperature and air pressure at 10 to 50 km height. Skyline S2 is a collaborative development effort between Airbus NL, TNO, VDL and AALTO.

Zephyr-2-Zephyr application 

The primary application of Skyline S2 currently under development is the inter-Zephyr laser communications link, enabling Q-band RF feeders for remote 5G/6G connectivity hubs between GEO and LEO satellites and HAPS (figure above). For this use case, both Zephyr platforms are equipped with a LCT for a high-bandwidth optical communications link. This link relays data from on-board Q-band terminals with on-ground RF antennas to feed the HAPS (figure left).


Main specifications

  • Capacity of up to 1 Gbit/s bi-direcitonal link over a distance of 100 km 
  • Complete LCT design weighs approximately 3 kg 
  • Consumes between 30 and 40 Watt of power

Read all about the technical specifications and test results in this paper


The Zephyr LCT comprises several key subsystems: an Optical Bench, a Coarse Pointing Assembly (CPA), an Optics Control Unit, a Laser Module and an Optical Modem. The LCT interfaces with the on-board RF modem and Zephyr Controller, residing in the nose pod of the Zephyr (figure to the left). The interconnections between the various subsystems are shown in the figure above. The 40 mm diameter aperture enables a bi-directional link initially capable of data transmission at 1 Gbit/s with a range of 100 km. The design allows for future upgrades to higher bandwidths and longer distances, maintaining a high link budget margin during the initial demonstration phase.

Download catalogue

The Laser Communications product catalogue is available for download here. This catalogue provides you further information on our company, our LaserPort optical ground stations and our LaserWing airborne terminals. If any questions arise or additional information is desired, please feel free to contact us.

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