Context: Bengaluru-based space start-up, Galaxeye Space has flown a synthetic aperture radar (SAR) developed by it on a High-Altitude Platform station (HAPS) of the National Aerospace Laboratories, based in Pune.
About Synthetic Aperture Radar
- SAR is a powerful remote sensing tool that can see through cloud and vegetation cover to picture the ground below.
- HAPS are like big drones, they can be moved, or made to hover over a certain country or a region.
High-altitude platform stations:
- High-altitude platform stations (HAPS) are aircrafts that can fly at an altitude of 18-20 km from the ground (stratosphere), almost double the heights attained by commercial aeroplanes.
- HAPs are of many types: Balloons, airships and unmanned aerial vehicles.
- They are typically solar-powered so can remain in the air for months and even years, giving the advantage of a satellite.
- They can carry payloads of up to 40 kg.
Differences between HAPS and Satellites:
| S.No. | Category | HAPS | Satellites |
| Altitude | Operates in the stratosphere, 18-20 km above the Earth. | Range varies from Low Earth Orbit (LEO) at 200-2000 km to Geostationary Earth Orbit (GEO) at 36,000 km. | |
| Coverage | Covers a specific area, typically up to 400 km in diameter. | Can offer spot coverage (LEO) as well as global coverage (GEO). | |
| Latency | Lower latency due to their closer proximity to Earth, ideal for real-time applications. | Higher latency, especially for GEO satellites, which can cause signal delays. | |
| Cost | Generally cheaper than satellites due to no need for a rocket launch. | Launching and maintaining satellites in space is expensive. | |
| Applications | Providing remote internet connectivity, remote sensing, disaster response communication, border surveillance and defence applications. | Global communication networks, navigation (GPS), earth observation. |
