UPSC Mains Current Affairs for 4 May 2026

Drishti Satellite Opto-SAR Technology: How Drishti Satellite Opto-SAR Technology is Transforming Space Imaging

May 4, 2026

Drishti Satellite Latest News

Indian space start-up GalaxEye launched its first satellite 'Drishti' aboard a SpaceX Falcon 9 rocket from Vandenberg Space Force Base, California, as one of 45 payloads on the CAS500-2 mission.
Founded by IIT Madras alumni, GalaxEye has created the world's first satellite capable of capturing optical and radar images simultaneously of the same location — a technological first in space imaging.

Space Imaging

Space imaging refers to the collection of visual and electromagnetic data from space, used to map celestial bodies, track cosmic phenomena, and monitor Earth's environment.
This technology translates data from across the electromagnetic spectrum into high-resolution imagery.

Key Technologies

Optical Sensors: Capture visible light to produce detailed, high-resolution photographs of Earth and deep-space objects.
Synthetic Aperture Radar (SAR): Emits microwave pulses to map terrain. Because it doesn't rely on sunlight, it can image through clouds, smoke, and total darkness.
Infrared and Thermal Imaging: Detects heat signatures, which is essential for studying star formation in deep space and monitoring wildfires or climate patterns on Earth.
Hyperspectral Imaging: Breaks down light into hundreds of narrow bands, allowing scientists to identify the exact chemical composition of minerals, vegetation, and gases.
AI and Cloud Computing: Modern space systems utilize artificial intelligence directly on orbit to process petabytes of imagery instantly, enabling real-time change detection and analysis.

Limitations of Existing Imaging Technologies

Space imaging satellites currently use one of two technologies:
- Optical/Multi-spectral Imaging — Works like a normal camera, producing clear, intuitive, and easy-to-understand images.
  - However, it is ineffective during cloudy weather or night time — a significant limitation for tropical countries like India where cloud cover is frequent and unpredictable.
- Synthetic Aperture Radar (SAR) — Uses radar signals that can penetrate clouds and capture images continuously regardless of weather or lighting conditions.
  - However, SAR images are not intuitive — like X-ray images, they require trained experts to interpret the data, limiting their usability for general users.

The Gap — Why Fusion is Needed but Difficult

Users currently need data from multiple satellites — optical data for clarity and SAR data for continuity and all-weather availability.
While superimposing these two datasets often works, it has serious limitations.
The two satellites are not watching the same place at the same time, and the angles at which they observe Earth can be very different — making accurate data fusion a persistent challenge.

What Makes Drishti Unique — The Opto-SAR Technology

Drishti is the world's first satellite equipped with both optical and SAR sensors operating simultaneously to capture images of the same location at the same time.
GalaxEye calls this proprietary innovation "Opto-SAR technology."

The Core Technological Challenge — and How It Was Solved

SAR and optical sensors are designed differently and look at Earth at different angles.
If placed side by side without synchronisation, the optical sensor might be capturing Bengaluru while the SAR sensor is simultaneously capturing Dubai.
GalaxEye developed a proprietary technology stack that synchronises the functionalities of both sensors, enabling them to look at the exact same location at the same time.
Hence, it eliminates the need for users to manually align datasets from two different satellites.

The AI Dimension

When optical sensors are unable to capture images due to clouds, Drishti uses Artificial Intelligence to regenerate optical-like images from SAR data — further bridging the gap between clarity and all-weather reliability.

Why This Problem is Particularly Indian

Most traditional satellite companies are based in Western countries where weather is relatively more predictable and skies are cleaner.
They do not face the same intensity of cloud cover challenges that countries like India — located in the tropics — routinely experience.
GalaxEye is therefore solving a problem specific to India and the developing world — making space imagery available all the time and understandable to all kinds of users.

Applications of Drishti

The data produced by Drishti has both civilian and military applications including:
- agriculture monitoring,
- disaster management,
- urban planning,
- infrastructure monitoring,
- border surveillance, and
- defence intelligence.

India's Growing Space Start-up Ecosystem

GalaxEye is part of a rapidly emerging wave of Indian private space companies making significant technological contributions.
Other notable start-ups include:
- Agnikul Cosmos (IIT Madras) — which built the world's first 3D-printed rocket engine, Skyroot — which tested India's first privately built rocket, and
- Pixxel, Dhruva Space, and Bellatrix — demonstrating impressive innovations in satellite technologies.
This ecosystem has been significantly enabled by India's Space Policy 2023, which opened end-to-end space activities to private players.

Source: IE

Drishti Satellite FAQs

Q1: What is Drishti satellite opto-SAR technology?

Ans: Drishti satellite opto-SAR technology combines optical and radar imaging to capture simultaneous data of the same location, improving accuracy, clarity, and all-weather monitoring capabilities.

Q2: Why is Drishti satellite opto-SAR technology important?

Ans: Drishti satellite opto-SAR technology solves limitations of traditional imaging by enabling continuous observation even during clouds or night, crucial for countries like India.

Q3: How does Drishti satellite opto-SAR technology work?

Ans: Drishti satellite opto-SAR technology synchronizes optical and SAR sensors to capture real-time images of the same location, enhanced by AI for better interpretation.

Q4: What are the applications of Drishti satellite opto-SAR technology?

Ans: Drishti satellite opto-SAR technology is used in agriculture monitoring, disaster management, defence surveillance, urban planning, and infrastructure tracking.

Q5: How does Drishti satellite opto-SAR technology boost India’s space sector?

Ans: Drishti satellite opto-SAR technology highlights India’s growing private space ecosystem, supported by policy reforms and innovation from start-ups like GalaxEye.

NASM-SR Missile Salvo Test: How NASM-SR Missile Salvo Test Strengthens India’s Naval Power

May 4, 2026

NASM-SR Missile Salvo Test Latest News

India recently advanced its naval strike capabilities as the DRDO and the Indian Navy successfully conducted a salvo test of the indigenously developed Naval Anti-Ship Missile Short Range (NASM-SR) from a helicopter off the Odisha coast.
Two missiles were fired in quick succession from the same platform, marking the first successful salvo launch from a chopper.
The NASM-SR is designed for deployment from ship-borne helicopters and represents an upgrade over existing systems.
It incorporates advanced features such as “man-in-loop” guidance, allowing real-time control during flight, and “waterline hit” capability, which enhances its effectiveness in disabling enemy ships.
The test highlights the growing importance of helicopter-launched missiles in enhancing naval flexibility, precision strike capability, and maritime dominance.

Role of Helicopter-Launched Missiles in Naval Warfare

Helicopter-launched missile systems like the NASM-SR enhance naval combat capability by allowing forces to strike enemy ships from a safe distance without exposing their own vessels to direct threats.
This is crucial for anti-surface warfare and maintaining sea control in contested maritime zones.
The Indian Navy already uses systems like the British-origin Sea Eagle missile deployed on Sea King 42B helicopters, enabling ship-based helicopters to launch precision strikes.
This flexibility makes such systems highly effective in modern naval operations.

Need for NASM-SR: Modernising India’s Naval Missile Capability

The older Sea Eagle missiles, introduced in the 1980s, have become outdated and lack modern technological capabilities. A major drawback is their heavy weight (around 580 kg), limiting the number of missiles a helicopter can carry.
To address these limitations, the DRDO initiated the development of a lighter, more advanced, and indigenous missile in the early 2010s, aimed at enhancing operational flexibility.
The project involved multiple premier DRDO laboratories, including:
- Research Centre Imarat (Hyderabad)
- Defence Research and Development Laboratory
- High Energy Materials Research Laboratory (Pune)
- Terminal Ballistics Research Laboratory (Chandigarh)
The NASM-SR is being produced with the participation of private sector partners, MSMEs, and start-ups, strengthening India’s indigenous defence manufacturing ecosystem.

NASM-SR Missile: Design and Key Features

The NASM-SR missile is designed with a two-stage propulsion system, comprising a solid booster rocket for initial thrust and a long-burn sustainer engine for extended flight.
It is equipped with advanced subsystems, including a seeker for target detection and tracking, a radio altimeter to measure altitude above sea level, and a high-bandwidth two-way data link that enables real-time communication between the missile and the operator in the helicopter.
Weighing around 380 kg, it is significantly lighter than older systems, allowing helicopters to carry more missiles.
Although its range (55 km) is lower than that of earlier missiles, it compensates with improved technology and operational flexibility.
The missile uses a radio proximity fuse to detonate its warhead when it reaches close proximity to the target, ensuring effective impact.

Advanced Capabilities of NASM-SR: ‘Man-in-Loop’ and ‘Waterline Hit’

Many modern navies have helicopter-launched missiles that have these two features: ‘man-in-loop’ and ‘waterline hit’.

‘Man-in-Loop’ Guidance

The NASM-SR incorporates a “man-in-loop” feature, allowing a human operator to modify the missile’s trajectory during flight.
Enabled by a two-way data link, this system provides real-time feedback and control, making the missile more precise and adaptable.
It is particularly useful in crowded maritime environments, reducing the risk of accidental targeting and improving effectiveness against moving or evasive threats.
Unlike older “fire-and-forget” missiles such as the Sea Eagle, which cannot be redirected after launch, the NASM-SR’s guided control ensures greater operational flexibility and accuracy, especially in dynamic combat scenarios.

‘Waterline Hit’ Capability

Another key feature is the “waterline hit” capability, where the missile targets the area just above or at the waterline of a ship.
This is a structurally vulnerable point, and a strike here can cause severe damage, rapid flooding, and potentially sink the vessel.
This precision targeting significantly enhances the missile’s lethality compared to earlier systems lacking this capability.

NASM-SR Salvo Test: Demonstrating Enhanced Strike Capability

The recent test involved firing two NASM-SR missiles in quick succession from a single helicopter, showcasing the system’s ability to execute a salvo launch.
The test has operational significance:
- Demonstrates capability to overwhelm enemy ship defence systems
- Enhances effectiveness in real combat scenarios
- Increases chances of successful target neutralization
The salvo test highlights a major leap in India’s naval strike capability, combining precision, survivability, and multi-target engagement to strengthen maritime warfare readiness.

Source: IE | ToI

NASM-SR Missile Salvo Test FAQs

Q1: What is the NASM-SR missile salvo test?

Ans: The NASM-SR missile salvo test involves firing multiple missiles in quick succession from a helicopter, demonstrating India’s advanced naval strike capability and defence readiness.

Q2: Why is the NASM-SR missile salvo test important?

Ans: The NASM-SR missile salvo test shows the ability to overwhelm enemy defences, improving effectiveness in real combat and strengthening India’s maritime security capabilities.

Q3: What features make NASM-SR missile salvo test significant?

Ans: The NASM-SR missile salvo test highlights features like man-in-loop guidance and waterline targeting, enabling precision strikes and adaptability against moving or evasive targets.

Q4: How does NASM-SR missile salvo test improve naval warfare?

Ans: The NASM-SR missile salvo test enhances flexibility, survivability, and multi-target engagement, allowing helicopters to strike from safe distances in contested maritime environments.

Q5: Who developed the NASM-SR missile used in the salvo test?

Ans: The NASM-SR missile salvo test was conducted using an indigenous missile developed by DRDO with support from private sector partners, MSMEs, and start-ups.