🗞️ Why in News The Defence Acquisition Council (DAC) approved a total Rs 3.60 lakh crore package including High-Altitude Pseudo-Satellite (HAPS) systems for the Indian Air Force (~Rs 15,000 crore), while the Union Budget 2026-27 simultaneously allocated funds for three new astronomical observatories at Ladakh’s Hanle Dark Sky Reserve — including a 13.7-metre telescope that would be among the world’s largest optical telescopes.

High-Altitude Pseudo-Satellites (HAPS) — India’s Stratospheric ISR Platforms

What Are HAPS?

High-Altitude Pseudo-Satellites (HAPS) are unmanned aerial platforms — typically solar-powered airships or fixed-wing aircraft — that fly in the stratosphere at 18–22 km altitude, filling the capability gap between:

  • Low-orbit satellites (high cost, limited dwell time over specific areas)
  • Conventional UAVs/drones (low altitude, shorter range, more vulnerable)
Platform Type Altitude Dwell Time Cost
LEO Satellite 400–1,200 km Overflight (minutes/orbit) Very High
HAPS 18–22 km Months (solar-powered) Medium
High-altitude UAV (HALE) 15–18 km Weeks Medium
Medium-altitude UAV (MALE) 5–10 km Days Lower
Tactical UAV 1–5 km Hours Low

Key capabilities of HAPS:

  • Persistent ISR: Optical and infrared sensors that can monitor a large area (footprint: 500–800 km diameter at 20 km altitude) continuously for months
  • Communications relay: Can serve as an aerial communications hub, extending network coverage to areas without satellite or fibre connectivity
  • Electronic intelligence (ELINT): Signals intelligence at altitude without risking crewed platforms

Why India Needs HAPS Now

2017 Doklam standoff context: During the 73-day face-off between Indian and Chinese troops at Doklam (Bhutan-India-China trijunction), India’s surveillance of Chinese military build-up relied heavily on satellites with intermittent coverage and UAVs that were range-limited from Indian airbases. A HAPS platform stationed over the Himalayas could provide 24/7 continuous coverage.

China’s HAPS development: China has been actively developing HAPS systems (Caihong-T4 and Qimingxing series) since 2015. A Chinese HAPS capable of monitoring India’s military deployments in the Himalayas from Chinese territory would give the PLA a significant intelligence advantage.

Other applications:

  • Monitoring ceasefire lines (LoC in J&K, LAC in Ladakh)
  • Disaster management surveillance (floods, earthquakes)
  • Maritime domain awareness over the Indian Ocean
  • Communication support for troops in remote mountains

India’s Indigenous HAPS Development

NAL (National Aerospace Laboratories, Bengaluru) successfully tested a prototype HAPS in February 2024 at the Challakere Aeronautical Test Range, Karnataka. Target specs for the IAF variant:

  • Wingspan: 30 metres
  • Operating altitude: 23 km
  • Power: Solar panels on upper wing surface with battery storage for night operations
  • Delivery: By 2027

Industrial partners: HAL (manufacturing, integration) and NewSpace Research and Technologies (private sector partner, Bengaluru — India’s leading HAPS developer).

New Telescopes for Ladakh — Astronomical Infrastructure Push

Hanle Dark Sky Reserve

The Hanle Dark Sky Reserve in Ladakh (established 2022) is the world’s largest high-altitude dark sky reserve, at ~4,500 metres altitude. Low population density, minimal light pollution, exceptional atmospheric transparency, and high number of clear nights (~250–300 per year) make it ideal for optical and infrared astronomy.

Three Facilities

1. National Large Solar Telescope (NLST)

  • Aperture: 2 metres (the largest solar telescope in Asia on completion)
  • Location: Merak region, near Pangong Tso
  • Timeline: 5–6 years
  • Wavelengths: Visible and near-infrared
  • Purpose: High-resolution imaging of solar features (sunspots, solar flares, magnetic field dynamics, space-weather forecasting)

Space weather significance: Large solar flares and coronal mass ejections (CMEs) can disrupt satellite communications, power grids, and navigation systems (GPS). India needs independent solar monitoring for early warning.

2. National Large Optical-Near Infrared Telescope (NLOT)

  • Aperture: 13.7 metres (segmented mirror with 90 hexagonal segments)
  • Location: Hanle, Ladakh
  • Timeline: ~1 decade
  • Purpose: Deep sky observation — exoplanet detection, stellar evolution, supernovae, dark matter/dark energy studies
  • Scale context: This would place NLOT among the world’s 3–4 largest optical telescopes. The 30-metre Telescope (TMT, Mauna Kea) and the European Extremely Large Telescope (ELT, 39.3 metres, Atacama, Chile) are the largest under construction globally.

3. Himalayan Chandra Telescope (HCT) Upgrade

  • Current: 2.01-metre aperture (operational since 2000)
  • Upgrade: 3.7-metre segmented primary mirror
  • Operator: Indian Institute of Astrophysics (IIA), Bengaluru
  • Control: Remote-operated from CREST (Centre for Research and Education in Science and Technology), Hosakote, Karnataka

Why remote operation? At 4,500m altitude, regular human operation is physically taxing. The remote telescope model pioneered by HCT allows round-the-clock observations by scientists at lower altitude.

Indian Astronomy Infrastructure Context

India’s existing major observatories:

  • Giant Metrewave Radio Telescope (GMRT): Pune; 30 dish antennas; operated by NCRA-TIFR
  • Vainu Bappu Observatory: Kavalur, Tamil Nadu; 2.3-metre VBT
  • Indian Astronomical Observatory (IAO): Hanle, Ladakh (where HCT is located)
  • AstroSat: India’s first multi-wavelength space observatory (launched 2015); observes in UV to hard X-ray

UPSC Relevance

Prelims: HAPS (altitude range, applications, NAL prototype), Doklam standoff (2017), Challakere Aeronautical Test Range (Karnataka), Hanle Dark Sky Reserve (world’s largest high-altitude), NLST (2m, solar), NLOT (13.7m, segmented), HCT (IIA, remote operation, Hosakote), GMRT (Pune), AstroSat, NewSpace Research and Technologies, NAL. Mains GS-3: Defence technology indigenisation; UAV/HAPS capabilities and border surveillance; India’s space weather preparedness; scientific infrastructure investment; astronomy and space exploration.

📌 Facts Corner — Knowledgepedia

HAPS (High-Altitude Pseudo-Satellites):

  • Altitude: 18–22 km (stratosphere)
  • Dwell time: Months (solar-powered)
  • Footprint: 500–800 km diameter area from 20 km
  • IAF approval: DAC granted AoN (Acceptance of Necessity)
  • Cost component: ~Rs 15,000 crore (out of Rs 3.60 lakh crore total DAC package)
  • Indigenous: NAL prototype tested Feb 2024 at Challakere, Karnataka
  • Partners: HAL + NewSpace Research and Technologies
  • Target: 30m wingspan, 23 km altitude, by 2027

Ladakh Telescopes:

  • NLST: 2-metre solar telescope | Merak/Pangong Tso | 5–6 years
  • NLOT: 13.7-metre optical-NIR | Hanle | ~1 decade | 90 hexagonal segments
  • HCT upgrade: 2.01m → 3.7m | Hanle | remote-operated from CREST, Hosakote
  • Location: Hanle Dark Sky Reserve — world’s largest high-altitude DSR (~4,500m)

Key Telescope Comparisons:

  • World’s largest optical (operational): GTC (10.4m, La Palma, Spain)
  • ELT: 39.3m (European Southern Observatory, Atacama, Chile; under construction)
  • TMT: 30m (planned, delayed at Mauna Kea)
  • HCT: Operated by IIA (Indian Institute of Astrophysics), Bengaluru

Other Relevant Facts:

  • AstroSat: India’s first multi-wavelength space observatory; launched 2015 by ISRO; observes UV to hard X-ray
  • GMRT: Giant Metrewave Radio Telescope; Pune; 30 dishes; operated by NCRA-TIFR
  • Doklam Standoff 2017: 73-day face-off at Bhutan-India-China trijunction; HAPS would address surveillance gaps exposed
  • Space weather: Solar flares/CMEs can disrupt GPS, power grids, satellites; NLST provides independent monitoring capability

Sources: Drishti IAS, GKToday