Mention salient features of ‘Mission Drishti’. Discuss the imaging techniques used in the satellite launched on 3rd May 2026. Why it is being considered world’s first satellite of its kind ?
🧭 How to think about this question · directive: “mention / discuss / why”
Decode the demand
- Three directives, three parts: 'mention' the salient features (brief, factual), 'discuss' the imaging techniques (explain how each works and why they are combined), 'why' it is called the world's first (give the reasoning, not just the label).
- The act in one line: a private Indian startup flew an optical camera and a radar on one satellite and fused their data at source; everything in the answer hangs on this.
- The trap: writing a general essay on India's space reforms, or describing SAR vaguely as 'advanced imaging'. The examiner wants the physics in plain words and the precise reason earlier satellites did not do this.
- Carry the keywords: passive versus active sensor, multispectral, synthetic aperture, parallax, temporal gap, co-registration, fusion at source, OptoSAR.
Think in a structure
- Open with the date, the builder, the two verified tags (largest private satellite, world's first OptoSAR), then turn to the three demands.
- One heading per demand in the question's words: features as crisp one-line points; techniques as a comparison table plus a flowchart of fusion; the 'first' as a contrast with how optical and radar were flown before.
- End as an administrator: what the government, IN-SPACe and NSIL can do so one satellite becomes a constellation; close on the Indian Space Policy 2023's vision rather than a generic line.
Facts checked at source (2)· open
- The Prime Minister described Drishti as the world's first OptoSAR satellite and the largest privately built satellite in India.PIB — PM congratulates GalaxEye on Mission Drishti (3 May 2026) ↗“the successful launch of the world’s first OptoSAR satellite and the largest privately-built satellite in India is a testament to the youth’s passion for innovation and nation-building”
- GalaxEye (company technology page): combining data from two satellites, one SAR and one optical, introduces errors from differences in viewing angle (parallax) and capture time; OptoSAR fuses both sensors on one platform.GalaxEye Space (company page) — The technology behind OptoSAR imagery ↗“Traditionally, creating a multi-layered analysis required data from two separate satellites: one with a SAR sensor and one with an optical sensor. This approach introduces unavoidable errors from differences in viewing angle (parallax) and capture time (temporal gaps).”
Question: UPSC's CS (Main) 2026, GS Paper III — paper ↗. Guidance: Minimalist IAS, checked 8 Nov 2026 (how we verify). ·
Model answer· 644words · Minimalist IAS
Launched on 3 May 2026, Drishti, built by the Bengaluru startup GalaxEye, is India's largest privately built satellite and, in the Prime Minister's words, the world's first OptoSAR Earth-observation satellite: one spacecraft that sees in both light and radar. Its features, its two imaging techniques and the reason for the 'first' tag are examined below.
Salient features of Mission Drishti
- Private build: designed by an Indian startup under the 2020 space reforms, with IN-SPACe as single-window regulator and the Indian Space Policy 2023 opening Earth observation to non-government entities.
- Two sensors, one platform: a small satellite carrying an optical multispectral camera and a synthetic aperture radar (SAR) side by side.
- Fusion at source: both sensors image the same scene at the same instant; the data are merged into one analysis-ready product.
- All-weather, day-night sight: radar fills in where cloud, smoke or darkness blinds the camera, so coverage never breaks.
- Scale and sovereignty: India's largest privately built satellite, giving Indian users imagery that does not depend on foreign providers.
- PIB (3 May 2026): the Prime Minister called it 'the world's first OptoSAR satellite and the largest privately-built satellite in India'.
Imaging techniques used in the satellite
| Technique | Nature | How it works | Limit |
|---|---|---|---|
| Optical multispectral | Passive | Records reflected sunlight in visible and near-infrared bands | Blind at night and under cloud |
| Synthetic aperture radar | Active | Sends microwave pulses; echoes along the orbit build a fine image | Harder to interpret, speckle noise |
| OptoSAR fusion | Combined | Both frames captured together and co-registered pixel by pixel | New; yet to be proven at scale |
- Optical multispectral: a passive sensor reads colour, land use and vegetation health intuitively, as ISRO's Cartosat and Resourcesat series do.
- Synthetic aperture radar: an active sensor that uses the satellite's motion to mimic a long antenna, so a small antenna yields high resolution.
- Reads surface roughness, soil moisture and ground deformation; ISRO's RISAT series and the NASA-ISRO NISAR mission work on the same principle.
- Penetration: microwaves pass through cloud, smoke and night, so SAR maps monsoon floods and fires when cameras fail.
- OptoSAR fusion: pixels from both sensors, captured together, give one layered image with the detail of optical and the reliability of radar.
- Same scene
- optical frame + SAR frame at one instant
- co-registration
- fused product
- analysis-ready imagery
- Why fusion at source matters: two satellites see a scene from different angles and times, adding parallax and temporal-gap errors; one platform removes both.
- GalaxEye: data from separate SAR and optical satellites carry 'unavoidable errors from differences in viewing angle (parallax) and capture time'.
Why the world's first satellite of its kind
- Single-sensor tradition: national agencies flew optical and radar payloads on separate satellites; ISRO's Cartosat and RISAT are one example.
- Fusion done on the ground: earlier multi-sensor products merged downloaded datasets and inherited the parallax and time-gap errors.
- Drishti's claim: the first spacecraft to carry both sensors and fuse their data at source, which is what 'OptoSAR' denotes.
- Private first: the design came from a startup, not a national agency, marking the shift from ISRO as sole builder to ISRO as enabler.
Way forward for India's private space sector
- Anchor demand: government users should buy OptoSAR data for floods, crops and borders, giving startups a paying market.
- NewSpace India Limited, ISRO's commercial arm, can aggregate public demand into long-term contracts.
- Clear data policy: resolution and sharing rules under the Indian Space Policy 2023 so private imagery reaches disaster managers without delay.
- Domestic launch slots: priority on PSLV and SSLV for Indian small satellites, cutting dependence on foreign rideshares.
- Constellation, not a single satellite: several Drishti-class spacecraft would shorten revisit times enough for near-real-time response.
Drishti shows India's private space sector moving from launch services to frontier sensing. The Indian Space Policy 2023 envisions a thriving commercial space ecosystem; that vision is realised when such satellites multiply into constellations that serve Indian farmers, soldiers and disaster managers first.
Prepared by Minimalist IAS to the answer standard of Shivam Singh (mentor, 7 years) · facts checked against official sources (how we verify) · updated 8 Nov 2026. UPSC publishes no model answers: compare your structure and coverage with this, then write your own.
