CARTOSAT-2B

CARTOSAT-2B is an Indian Earth observation satellite operated by the Indian Space Research Organisation (ISRO). Launched on July 11, 2010, it occupies a Sun-synchronous low Earth orbit and forms part of the long-running Cartosat series, a family of spacecraft designed to collect detailed imagery of the Earth's surface. As of the time of writing, the satellite remains in orbit and continues to be tracked by the global space surveillance network under NORAD catalog identifier 36795 and the international designator 2010-035A.

Mission and Purpose

CARTOSAT-2B belongs to the Cartosat program, ISRO's dedicated line of high-resolution optical imaging satellites. The broader Cartosat series was conceived to provide India and its partner agencies with reliable, continuous remote sensing capability for a wide range of civil and governmental applications. These include land-use mapping, urban planning, infrastructure monitoring, agricultural assessment, disaster response, and cartographic projects — essentially any task that benefits from precise, high-resolution views of terrain and human development from space.

As the fourth satellite in the Cartosat series and the seventeenth spacecraft in India's broader Indian Remote Sensing (IRS) constellation, CARTOSAT-2B represents an incremental step in a program that has steadily grown in capability and ambition since the first IRS satellites were launched in the late 1980s. The IRS series is one of the world's most extensive civilian remote sensing constellations, and each new satellite has built upon lessons learned from its predecessors in terms of imaging resolution, onboard processing, and data downlink capacity.

The specific imaging instruments aboard CARTOSAT-2B and the precise details of its sensor specifications are not catalogued in the public tracking record reviewed here. What is well established is that the Cartosat-2 class of satellites is oriented toward sub-meter to low-single-digit-meter resolution panchromatic and multispectral imaging, making them well suited to applications that require detailed ground-feature discrimination. Data from the Cartosat series is routinely distributed through the National Remote Sensing Centre (NRSC), an ISRO facility, to government ministries, research institutions, and international partners.

The satellite's Sun-synchronous orbit is particularly well matched to the demands of Earth observation. By crossing any given point on the Earth's surface at approximately the same local solar time on each pass, a Sun-synchronous orbit ensures that lighting conditions remain broadly consistent from image to image, greatly simplifying the comparison of imagery taken weeks or months apart. This consistency is invaluable when monitoring gradual changes in land cover, detecting deforestation, tracking coastal erosion, or assessing the aftermath of floods and earthquakes.

Orbit and Tracking

CARTOSAT-2B orbits in a Sun-synchronous low Earth orbit with an apogee of approximately 645 km and a perigee of approximately 630 km, giving it a very nearly circular orbital profile. The inclination of 98.0° is characteristic of Sun-synchronous orbits, which are slightly retrograde relative to the Earth's rotation. This retrograde tilt, combined with the natural precession of the orbit's plane caused by Earth's equatorial bulge, allows the orbital plane to precess at roughly the same rate that the Earth progresses around the Sun — keeping the satellite's ground track in sync with local solar time throughout the year.

With an orbital period of 97.3 minutes, CARTOSAT-2B completes roughly 14 to 15 orbits of the Earth each day. Over the course of a full repeat cycle, the satellite's ground track systematically covers the entire Earth's surface at accessible latitudes, enabling systematic global or near-global coverage. The near-circular orbit minimizes variation in the satellite's altitude and, by extension, in the imaging geometry and ground resolution on any given pass.

The satellite was launched on July 11, 2010, and has remained in orbit continuously since that date. Its low-Earth orbit at this altitude means that atmospheric drag, while minimal, is non-negligible over long timescales. However, the satellite has shown no signs of imminent decay and remains active in current tracking data. Its orbital elements are regularly updated through the U.S. Space Surveillance Network and are available to the public via resources such as Space-Track.org and the LowEarth tracking platform.

For observers and researchers using the NORAD catalog, the satellite is indexed at catalog number 36795. The COSPAR international designator 2010-035A identifies it as the primary payload of the 35th launch of 2010, providing an unambiguous record that links the spacecraft to its launch event in the historical spaceflight registry.

Design and Operator

CARTOSAT-2B was built and is operated by the Indian Space Research Organisation, the national space agency of India. ISRO was established in 1969 and has since grown into one of the world's major space agencies, with a broad portfolio spanning launch vehicles, communications satellites, planetary exploration, and, notably, Earth observation. The organization has placed particular emphasis on developing indigenous remote sensing capacity, and the IRS and Cartosat programs represent the most mature expression of that priority.

The satellite's manufacturer is not recorded in the public catalog data available for this entry. In general, ISRO has relied heavily on its own in-house engineering centers — particularly the U R Rao Satellite Centre (formerly ISAC) in Bengaluru — for the design and fabrication of its remote sensing satellites. The Cartosat-2 class of spacecraft are typically three-axis stabilized platforms, designed to maintain precise pointing of their imaging instruments toward the Earth's surface while managing onboard power, thermal control, and data storage.

The mass of CARTOSAT-2B is not listed in the current tracking catalog entry. Launch vehicle details and exact spacecraft mass are sometimes omitted from public satellite catalogs, particularly for payloads where the operator has not formally disclosed full technical specifications. The satellite was placed into its operational orbit as the primary payload of its launch, as indicated by the "A" suffix in its international designator.

India's investment in the Cartosat series reflects a broader national strategy of achieving self-reliance in space-based geospatial intelligence. Rather than depending on foreign data providers for high-resolution imagery of Indian territory and neighboring regions, ISRO has systematically built a domestic constellation capable of serving national security, civil administration, and scientific research simultaneously.

Significance and Legacy

Within the history of Indian spaceflight, CARTOSAT-2B holds a specific place as the seventeenth satellite in the IRS lineage. That lineage stretches back more than three decades and represents one of the developing world's most sustained and successful civil remote sensing programs. The scale and consistency of the IRS program has enabled India to build up a significant national archive of Earth observation data, which supports everything from agricultural yield forecasting to urban master planning to environmental regulation.

The Cartosat-2 subclass, of which CARTOSAT-2B is a member, was specifically designed to offer improved imaging resolution and agility compared to earlier Cartosat satellites. The ability to acquire imagery not just in the nadir direction but across a range of look angles — as is characteristic of the Cartosat-2 design philosophy — expands the effective revisit rate and the operational flexibility of the system, allowing urgent requests for imagery of specific locations to be fulfilled more rapidly than a purely nadir-pointing instrument could manage.

In the broader context of global Earth observation, CARTOSAT-2B represents the kind of national investment that has become increasingly common as space-capable nations recognize the strategic and economic value of maintaining their own overhead imaging assets. The satellite is one of dozens of such spacecraft now operated by countries across Asia, Europe, and the Americas, collectively providing a level of global coverage and data availability that would have been extraordinary by the standards of even two decades ago.

As of the most recent tracking data, CARTOSAT-2B remains in orbit, having now exceeded well over a decade of on-orbit time since its July 2010 launch. Whether the spacecraft is still fully operational or in a degraded state is not specified in the public catalog record consulted for this article.

How to Spot It

CARTOSAT-2B orbits at an altitude between approximately 630 and 645 km, placing it well within the zone regularly swept by ground-based observers scanning for satellites in low Earth orbit. At this altitude, the satellite can be visible to the naked eye under favorable conditions — specifically when the observer is in twilight and the satellite is still sunlit, a configuration that typically occurs for a window of roughly one to two hours after sunset or before sunrise.

Because detailed brightness data for CARTOSAT-2B are not catalogued in the tracking record used here, its precise visual magnitude during typical passes is not known. However, satellites in this orbital class commonly appear as a steady, moderately bright point of light moving steadily across the sky over the course of two to four visible minutes per pass. The satellite's 97.3-minute orbital period means that favorable passes can repeat on successive nights at similar times, shifting slightly as the geometry evolves. Using the orbital elements available through LowEarth or compatible prediction tools, observers can calculate upcoming passes for their specific location with good accuracy.