Scientists at the Council of Scientific and Industrial Research (CSIR)-National Aerospace Laboratories (NAL) conducted, in February 2024, a successful testing of an unmanned aerial vehicle (UAV), called the High-Altitude Pseudo-Satellite (HAPS), at Challakere, Karnataka. It is seen as a huge technology breakthrough as the UAV was a prototype of a new-generation UAV which could fly at about 20 kilometres from the ground and run entirely on solar power. Further, it has the capability to remain in air for months. This vehicle belongs to the category of High-Altitude Long-Endurance (HALE) vehicles. According to the chief scientist at the NAL, the HAPS test has given the impetus to design a bigger system.
This prototype HAPS spent eight and a half hours in the air. The prototype was five metres long with a wingspan of 11 metres and weighed about 23 kilograms. NAL is in the process of testing the HAPS for 24 hours in the coming months. NAL has planned a series of tests and is anticipating to culminate in a full-bodied craft with a wingspan of 30 metres, by 2027. Once done, the HAPS would be able to rise to a height of 23 kilometres and could remain in the air for about 90 days.
About High-Altitude Pseudo-Satellite
High-Altitude Pseudo-Satellites (HAPS) are similar to drones, with the exception that they are designed to operate in the stratosphere. This layer is far above the altitude at which a commercial aircraft would fly. HAPS could be powered by solar cells and battery system which would help them operate for days on end. Applications of a fully functional HAPS range from 5G wave beaming to surveillance. They are more adaptable than satellites and could map a region of land from the above. They act as ‘towers in the sky’. HAPS could be useful in situations, such as disaster management.
There are two categories of HAPs. First is lighter-than-air which are usually balloon aerostats or airships filled with helium gas. It requires less energy in launching and stabilisation over a fixed spot.
Second is heavier-than-air (HTA) which encompass both manned airplanes and UAVs, serving critical roles in various applications. Operating on the principle articulated by Bernoulli, these vehicles rely on lift forces to sustain flight despite their weight. Propulsion is achieved through electric motors, jet engines, or other thrust mechanisms, ensuring sufficient forward momentum to counteract gravity.
Crucially, continuous motion is essential for the HTA HAPS to maintain altitude. Typically, these vehicles operate within circular flight paths, spanning up to a 2 km radius, with ground-based control mechanisms managing their movements. This controlled aerial domain facilitates diverse functionalities, ranging from surveillance to communication and beyond, making HTA HAPS indispensable assets in modern aerospace endeavours.
Need for HAPS Vehicles
- Endurance and persistence Unlike conventional UAVs, which are typically battery-powered and have limited flight durations, HAPS vehicles offer extended endurance. These vehicles can remain airborne for prolonged periods, allowing for continuous monitoring and surveillance without the need for frequent recharge or replacement.
- Altitude advantage Operating at an altitude of approximately 20 km above the ground, HAPS have a significant altitude advantage over traditional UAVs. This altitude provides a broader field of view, enabling coverage of larger areas compared to low-flying drones. Additionally, their altitude allows for a comprehensive perspective with minimal obstruction, enhancing surveillance capabilities.
- Continuous monitoring While satellites offer wide-area coverage, their orbits limit their ability to provide continuous monitoring of specific regions. HAPS address this limitation by loitering over designated areas for extended periods, maintaining constant surveillance without the need for orbital adjustments.
- Cost-effectiveness Geostationary satellites, while capable of continuous observation, are expensive to deploy and maintain. HAPS offer a more cost-effective alternative for persistent surveillance, providing comparable capabilities at a fraction of the cost.
- Flexibility and repurposability Unlike traditional satellites, which are fixed in their orbits once deployed, HAPS offer greater flexibility and adaptability. These vehicles can be repositioned and repurposed as needed, allowing for dynamic response to changing surveillance requirements.
- High resolution imaging HAPS are equipped with advanced imaging capabilities, capable of capturing detailed imagery with high resolution. This enables precise monitoring and analysis of target areas, facilitating enhanced situational awareness and intelligence gathering.
- Strategic importance The development of HAPS has been driven by strategic considerations, particularly in border surveillance and monitoring. In regions prone to geopolitical tensions, such as the aftermath of the Doklam stand-off, continuous monitoring of border areas is essential for early detection of changes or movements.
The Council of Scientific and Industrial Research-National Aerospace Laboratories (CSIR-NAL), established in 1959, stands as India’s sole government aerospace research and development laboratory within the civilian sector. Positioned as a hub for high-technology pursuits, CSIR-NAL specialises in cutting-edge aerospace disciplines.
CSIR-NAL is dedicated to the design and construction of small to medium-sized civil aircraft. Its laboratory actively contributes to and supports all national aerospace initiatives, thus embodying its commitment to advancing India’s aerospace capabilities and achieving excellence in the field.
Application of HAPS Vehicles
HAPS technology offers a wide array of applications across various sectors. These applications include:
- National and regional communication networks HAPS can provide extended coverage for both commercial and military radio-communication systems, offering services such as cellular, voice, Internet, and video over large areas, including rural and urban regions. They serve as vital communication infrastructure, especially during natural disasters and conflicts.
- Military and intelligence operations HAPS facilitate permanent surveillance and reconnaissance missions with high resolution, aiding in coastal or border observation, missile launch detection, and homeland security missions.
- Television broadcasting HAPS enable extended coverage for local and national television broadcasting, including high-definition TV (HDTV) and digital audio services, over operational distances of up to 1000 km.
- Radio-communication services HAPS support various radio-communication services such as data communications, distance learning, and financial transactions, with the potential for global coverage through collaboration with satellite systems.
- Surveillance for security purposes HAPS play a crucial role in persistent surveillance for detecting illegal activities like drug trafficking, signal gathering, spectrum monitoring, and monitoring ground vehicles, aircraft, and ships for traffic control and security surveillance.
- Weather monitoring and forecasting HAPS contribute to remote sensing of regional weather conditions, aiding in forecasting, atmospheric data gathering, and hurricane detection and monitoring.
- Environmental conservation HAPS are utilised for surveillance of pollution levels, including monitoring concentrations of carbon dioxide, ozone, and radiation levels, even at high altitudes, to support environmental conservation efforts.
- Space observations and radio-signal monitoring HAPS enable space observations and radio-signal monitoring from both space and ground stations.
- Enhancement of global positioning system (GPS) HAPS can enhance the reliability and accuracy of the GPS by incorporating differential GPS sources into their payload.
- Scientific exploration HAPS technology contributes to scientific exploration missions, including the exploration of the Moon, Mars, and other planets.
Technological Challenges of HAPS
There are significant technological obstacles in the process of creating an autonomous flying machine which is solely powered by solar energy and which as to stay in atmosphere for several months. This is why a full-fledged HAPS vehicle has not been created, despite decades of work, by the engineers. HAPS appears to be feasible in the near future because of the advancements in solar cell, batteries and composite material technologies.
Creating enough solar power to keep the aircraft in the air, the payloads functioning and the batteries charged are the primary hurdles. These planes require extremely thin solar films and there are only a couple of firms in the world that are capable of making thin solar cell films. Enough batteries are needed for operations to last through the night. There are also difficulties pertaining to design. For limiting the power consumption, the vehicle has to be extremely lightweight, yet stable. This ascent into the sky is challenging, given the air turbulence in the atmosphere and the fact that these are relatively light planes.
Their flight could be facilitated by the climate in the area between 17 and 23 kilometres above the Earth’s surface. It is the perfect wind speed for lightweight aircrafts to remain stable. Moreover, this altitude is advantageous for observation and surveillance tasks. However, it could get as cold as –50 degrees Celsius. Maintaining the temperature of electronics adds to the demand on power supplies. Furthermore, the density of the air is only roughly 7 per cent of that at sea level. This causes serious issues for the aircraft, when it comes to aspects such as lift and thrust production.
Global development efforts The development of HAPS is a global endeavour, with countries like China, South Korea, and the UK actively engaged in research and development. Additionally, private companies, including those in India, are investing in HAPS technology, indicating its growing importance in both military and civilian applications.
India and HAPS
India has begun its journey and is inching closer to HAPS. Since the past few years, India has been promoting research in emerging technologies to dependence on others for critical technologies in future. India has been adopting technology development early to have control over patents, business opportunities, and spin-off technologies.
According to NAL, India has moved into HAPS technology development at the right time. The successful test flight has proved the technological capabilities of India at par with other countries which are trying to develop this technology.
CSIR-NAL aims to design and build the HAPS’ propellers, battery management system, carbon-composite airframe, flight-control system, and the high-powered electric motors, which would be able to withstand extreme temperature ranges.
The successful test flight of NAL’s HAPS prototype signals a major advancement in the UAV technology. These solar-powered HAPS promise extended surveillance capabilities, overcoming the limitations of traditional UAVs and satellites. While challenges remain in engineering and operationalising HAPS, ongoing advancements suggest a bright future. India’s involvement underscores a strategic push towards indigenous innovation, positioning the country as a key player in the global race. As NAL continues its efforts, the potential for HAPS to transform surveillance, communication, and disaster response is immense, marking a significant milestone in aerospace technology.
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