High Altitude Pseudo Satellites
A sustainable alternative to satellites launched by rockets are solar powered planes that fly above the weather and act as transmission platforms for radio waves. Referred to as High Altitude Pseudo Satellites (HAPS) there are a number of systems presently under development.
• Zephyr-7 (owned by Airbus)
• Titan Aerospace (owned by Google)
• Ascenta (owned by Facebook)
• Sunlight Photonics
• Bye Aerospace The Zephyr-7 The Airbus owned Zephyr-7 is probably the leader in the field of High Altitude Pseudo Satellites.
An August 2014 trial saw the Zephyr-7 take off, fly for 11 days and then land without incident. The Zephyr-8 is under construction.
This is an excellent article on the Zephyr.
Titan Aerospace Now owned by Google, Titan Aerospace is developing HAPS that can be used to deliver wireless broad brand internet from an altitude of about 70,000 meters. News Report.
SUNLINK-X (under development) is designed for long endurance missions at high altitudes. It combines advanced airframe design with a regenerative power system and will take advantage of the lower wind speed and reliably intense sunlight and avionics cooling of the stratospheric environment.. SUNLINK-X is capable of supporting a 10kg payload and providing over 250W of continuous payload power. The PV and communications antennas are integrated in multi-functional skins. The platform is designed to operate autonomously or as part of a Sunfleet, supporting high performance, long endurance Communication Networks. The communication payloads will include radio frequency and Free Space Optics (FSO) subsystems for air-to-user (ATU), air-to-ground (ATG), air-to-air (ATA) and air-to-satellite (ATS) links.