NAL successfully tests solar-powered 'pseudo satellite'; UAV can float in air for days

New Delhi: India has taken the first step in realising a high-altitude pseudo-satellite that will fly in the stratosphere for days, capturing images of the ground below for a variety of purposes ranging from strategic to flood monitoring.

For over 10 days between Jan 23 and Feb 2, scientists at the National Aerospace Laboratories, Bengaluru carried out a series of flight trials of a scaled down version of the HAPS – a light-weight solar powered UAV – at the aeronautical test range at Challakere, reaching the first milestone of the ambitious programme.

“The plan is to have the full-scale prototype ready for trial by 2027. But there are multiple challenges that need to be overcome. Also, more capable battery packs are required for continuous day and night operations,” Abhay Anant Pashilkar, NAL director told DH.

At the trial, the subscale model with a wingspan of 12 metres flew for eight and half hours at an altitude of 3 km above the mean sea level.

“We will carry out two more flight trials this year possibly including one next month in which we plan to fly the HASP continuously for 24 hours,” he said.

Such aircraft are called pseudo-satellites because they can carry out some of the basic functions of a satellite – looking at the ground from high up in space – at a fraction of cost, as it doesn’t need a rocket for launching.

Another advantage of these platforms is that they can be easily moved to a location of choice unlike a satellite, which has a fixed predetermined path. Also, the HASPs can be linked to multiple ground stations simultaneously.

HAPS platforms are of interest to the military operators for intelligence, surveillance, and reconnaissance. They can be tailored for civilian roles like a telecom satellite in the time of environmental disasters.

Several nations and companies are currently working on a commercial HASP, but there is barely any product in the market yet.

“This is a significant development. The full-scale version will have multiple cameras and sensors for surveillance. We will look for a commercial partner for production,” commented Shekhar Mande, former director general of the Council of Scientific and Industrial Research. NAL is one of the CSIR’s constituent laboratories.

The full-scale model will have a wingspan of around 30 metres and weight of 150 kg. It will be a slow-moving aircraft with a speed of 80-100 km per hour, but will be able to fly for 90 days at an altitude of 17-20 km. The payload carrying capacity will be 15 kg.

Taking the HASP to such an altitude overcoming climatic factors like jet-stream in northern parts of the country as well as monsoon clouds will be yet another challenge. An equally critical task will be to find very powerful solar cells and batteries to sustain the HASP day and night for three months.

“The full-scale HASP will need a launch window and suitable launch location as it will need 14 hours to climb above the weather and there should not be any air-traffic in the flying zone for those hours. But once it is up, it can stay there for months, watching the ground silently,” said L Venkatakrishnan, programme director, high altitude platform at NAL.