SCATSAT 1

SCATSAT-1 is an Indian Earth-observation satellite operated by the Indian Space Research Organisation (ISRO) and dedicated primarily to ocean-wind monitoring, weather forecasting, and cyclone surveillance. Launched on September 25, 2016, it carries a microwave scatterometer instrument designed to measure near-surface wind speed and direction over the world's oceans — data that feeds into meteorological models used not only by Indian agencies but by major international organizations as well. Catalogued by NORAD under ID 41790 and identified internationally by the COSPAR designator 2016-059H, the satellite remains in orbit as of the time of writing.

Mission and Purpose

The central function of SCATSAT-1 is the continuous measurement of ocean surface winds. A scatterometer works by transmitting radar pulses toward the sea surface and analyzing the backscattered signal: the rougher the water — driven by wind — the stronger the return. By measuring this backscatter in multiple directions, the instrument can derive both the speed and direction of near-surface winds across broad swaths of ocean, providing an invaluable input for numerical weather prediction models.

SCATSAT-1 was designed to fill a critical operational gap that opened when India found itself heavily reliant on external data sources for cyclone forecasting and maritime weather prediction. For a period, India depended significantly on NASA's ISS-RapidScat instrument — a scatterometer mounted on the International Space Station — for wind-field data relevant to its forecasting needs. When that dependency became strategically untenable, and when India's own earlier ocean-observation satellite, Oceansat-2, saw its scatterometer payload reach the end of its useful life after roughly four and a half years of operation, the need for a dedicated domestic replacement became urgent. SCATSAT-1 was the direct answer to that requirement.

The satellite's Ku-band scatterometer is closely derived from the heritage of the Oceansat-2 instrument, carrying forward proven design concepts while benefiting from accumulated operational experience. Ku-band radar, operating in the microwave portion of the spectrum, is well suited to ocean-wind sensing because it penetrates cloud cover and functions regardless of daylight conditions, enabling round-the-clock, all-weather data collection. The wind-field products generated by SCATSAT-1 are not consumed solely by Indian meteorological services. They are also routinely ingested by NASA, the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and the National Oceanic and Atmospheric Administration (NOAA), underscoring the satellite's role within the global network of operational Earth-observation assets.

At the national level, SCATSAT-1 data directly supports cyclone prediction and tracking over the Bay of Bengal and the Arabian Sea — two of the world's most cyclone-prone ocean basins, both of which border India's coastline. Accurate, timely wind-field maps from the satellite help meteorologists identify developing low-pressure systems, track their intensification, and issue warnings that protect lives and infrastructure across the Indian subcontinent and surrounding regions.

Orbit and Tracking

SCATSAT-1 occupies a sun-synchronous orbit (SSO), a near-polar orbit class in which the satellite's orbital plane precesses at a rate that keeps it at an approximately constant angle relative to the Sun throughout the year. This geometry ensures that the satellite passes over any given point on Earth's surface at roughly the same local solar time on each visit — a highly desirable property for Earth-observation missions, since it means illumination conditions and atmospheric states are consistent across repeat passes, simplifying the comparison of data collected on different dates.

The satellite's current orbital parameters place its apogee at approximately 673 km and its perigee at approximately 598 km above Earth's surface, giving it a mildly elliptical path at a mean altitude that sits comfortably within the low Earth orbit regime. Its orbital inclination is 98.1°, consistent with the retrograde, near-polar geometry characteristic of sun-synchronous orbits. SCATSAT-1 completes one full orbit of Earth every 97.3 minutes, meaning it circles the planet roughly 14 to 15 times per day. At this cadence and with the wide-swath coverage enabled by its scatterometer antenna, the satellite can build up near-global ocean-wind maps within a relatively short revisit period — typically on a sub-daily timescale — which is precisely the refresh rate that operational weather forecasting demands.

The orbit's sun-synchronous character also means the satellite enjoys nearly continuous solar illumination on its power-generating panels during certain seasons, reducing reliance on battery storage and helping to sustain consistent instrument operations. The relatively modest altitude keeps signal path lengths manageable for both downlink communications and for the radar instrument itself, which must transmit and receive signals through the full column of atmosphere beneath it.

Design and Operator

SCATSAT-1 was conceived, built, and operated by the Indian Space Research Organisation, India's national space agency, which has developed one of the world's most active and cost-effective civil space programs over the past several decades. The satellite's bus was developed at the ISRO Satellite Centre in Bangalore (now known as the U. R. Rao Satellite Centre), while the science payload — the Ku-band scatterometer itself — was developed at the Space Applications Centre in Ahmedabad. This division of responsibility between two major ISRO centres reflects the organization's established practice of distributing spacecraft and instrument development across its network of specialized facilities.

The satellite is classified as a payload — that is, an active, functional spacecraft rather than a rocket body or debris object — and it is registered as property of India. Its specific mass is not recorded in the publicly available catalog data, and details of its structural configuration and subsystem design are not fully disclosed in open sources. What is known is that it belongs to the category of small to medium Earth-observation satellites typical of ISRO's remote-sensing portfolio, designed for long-duration operational service rather than short experimental campaigns.

SCATSAT-1's development drew directly on the technical legacy of Oceansat-2, which had demonstrated the viability of the Indian Ku-band scatterometer concept in an operational environment. By reusing and refining a proven payload design, ISRO was able to move relatively quickly from the identification of the capability gap to the delivery of a functioning replacement, a pragmatic approach consistent with the agency's broader engineering philosophy of incremental capability development.

Significance and Legacy

SCATSAT-1 occupies a meaningful place in India's Earth-observation history because it represents the consolidation of an indigenous operational scatterometry capability — one that ensures Indian meteorological services are not dependent on the continued goodwill or operational continuity of foreign assets for time-critical severe-weather data. The cyclones that develop over the Bay of Bengal and Arabian Sea can be among the most destructive natural phenomena to affect South Asia, and having a nationally controlled, continuously operating wind-sensing asset in orbit is therefore not merely a technical achievement but a matter of direct public-safety relevance.

The satellite's data contributions extend beyond Indian borders. By sharing wind-field products with organizations including NASA, EUMETSAT, and NOAA, SCATSAT-1 has become a recognized node in the international constellation of scatterometer satellites that together provide the sustained ocean-wind record that global climate and weather science depends upon. No single satellite can cover the entire ocean surface at all times, so the international community operates multiple scatterometers simultaneously, with each contributing complementary spatial and temporal coverage. SCATSAT-1's contribution to this collective observing system gives it significance that reaches well beyond the subcontinent.

The satellite also demonstrates ISRO's capacity to develop operational meteorological instruments to internationally recognized standards — a capability that positions the agency as a peer contributor to global Earth-observation infrastructure rather than merely a consumer of data produced elsewhere. The willingness of major agencies like NASA and NOAA to operationally ingest SCATSAT-1 products is itself an implicit endorsement of the instrument's calibration quality and data reliability.

Current Status

As of the catalog data current at the time of writing, SCATSAT-1 remains in orbit. Its operational status — whether the satellite is still actively collecting and transmitting data, or whether it has been retired while remaining physically in orbit — is not confirmed in the publicly available catalog record. The satellite's orbital parameters continue to be tracked, and its NORAD catalog entry (41790) remains active, allowing its position to be computed and predicted through standard two-line element sets.

For those interested in tracking the satellite, its sun-synchronous orbit at an inclination of 98.1° means it passes over virtually every latitude on Earth, including high northern and southern latitudes, during the course of each day. With an orbital period of 97.3 minutes, observers at any given ground station will see multiple passes per day, though whether the satellite is bright enough for naked-eye or small-telescope observation from the ground is not readily determinable from catalog data alone. Dedicated satellite-tracking tools, including the resources available on this site, can be used to generate precise pass predictions for any observer location, specifying elevation, azimuth, and timing for upcoming visible opportunities.