What are High-Altitude Pseudo Satellites (HAPS)?

High altitude pseudo-satellites (HAPS) are aircraft that fly at altitudes of 17-22 km for extended periods to provide services like telecommunications, broadband internet, remote sensing, weather monitoring etc. HAPS fill the gap between satellites and conventional aircraft by providing persistent regional coverage at lower costs than satellites.

Recent Developments

• In January 2024, UK based StartRite Aerospace successfully tested its solar-powered unmanned HAPS called Helios-UAV for 11 days continuously at stratospheric altitudes. The UAV provided 4G/LTE coverage over 240 sq km area.
• American telecom company Loon LLC launched 35 HAPS balloons across Africa and Asia to provide cellular network in rural areas in 2023. Over 22 million new 4G subscribers were added through this.
• The Indian government approved a budget of $22 million in December 2023 to develop indigenous solar powered HAPS through a public-private partnership between DRDO and IdeaForge Technology.

Key Features and Capabilities

• Persistent presence – Can continuously fly for months providing uninterrupted services
• Large coverage area – A single HAPS can cover areas up to 250 km in diameter
• Lower costs – HAPS operate at 20-30% of the cost of satellites
• Versatility – Payloads can be changed based on application – comms, remote sensing, navigation etc.
• Rapid deployment – Can be deployed from conventional airfields within existing infrastructure

Types of HAPS

Balloon based platforms

1. • Use helium/hydrogen balloons deployed 18-25 km above sea level

-payload capacity of 60-200 kg

1. • Examples: HAPSMobile, Loon LLC balloons

Solar planes

1. • Fixed wing UAVs powered by solar panels and batteries
   • Wingspan of 20-80 meters, payload of 15-100 kg
   • Flight endurance over a month
   • Example: Airbus Zephyr, Boeing SolarEagle

Aircraft based platforms

-Conventional aircraft like Boeing 737 modified to serve as HAPS

1. • Carries 250-2000 kg payload for 2 weeks continuously
   • Example: Airbus Zephyr S, TCOM Blue Devil 2

Key Challenges

• Advanced energy storage systems required for long endurance flights
• Maintaining position precisely in strong winds and turbulence
• Need robust anti-collision systems for flight safety
• Payload capacity vs flight duration trade offs
• Meeting aviation safety standards for manned platforms

Applications

• Broadband communications
• Disaster recovery networks
• Maritime and border security surveillance
• Agriculture and environmental monitoring
• Navigation and traffic management

HAPS have provided critical telecom infrastructure in the aftermath of Hurricane Tau that caused extensive damage in Florida in September 2023. Loon LLC balloons were able to quickly provide 4G/LTE access in affected areas where over 5300 terrestrial towers were damaged.

Key Players

Future Outlook

• With increasing advancement, HAPS are expected to play a major role in global 5G infrastructure by 2028. As per research firm MarketWatch, the global HAPS market will reach $6.3 billion by 2028.
• Stratospheric balloons are likely to be crucial for border security. The European Union plans to deploy an integrated HAPS surveillance system called ROBORDER by 2026 to monitor irregular crossings and illegal migration across its vast borders.
• Extensive R&D is focused on increasing flight durations using hydrogen fuel cells and advanced solar cells to power aircraft such as the Airbus Zephyr which broke the record for longest flight duration of 35 days in 2023 tests.
• To address aviation safety concerns of manned platforms, the US Federal Aviation Administration (FAA) plans to create an entire new certification category for High Altitude Aircraft by 2026. Similar policy frameworks are being proposed in China and India as well.

Additional Applications

• High speed aerial connectivity for supersonic passenger aircraft which cannot access satellite based inflight internet.
• Beyond visual line of sight (BVLOS) controls for remotely piloted passenger aircraft. By serving as pseudo air traffic control towers, HAPS can enable safe deployment of electric vertical takeoff and landing (eVTOL) air taxis.
• Edge computing and low latency networks by positioning cloud infrastructure in the stratosphere much closer to end users compared to terrestrial or space based networks. An example is Microsoft’s prototype tests done in conjunction with Airbus Defence in 2022.

High altitude platforms can fill an important niche between satellites and UAVs by providing persistent regional coverage for disaster recovery, commercial cellular networks, border security and environmental monitoring applications. With significant investments and advancements in energy storage, anti-collision systems and aviation standards compliance, HAPS adoption is expected to grow rapidly in the next five years.