IRNSS-1E

IRNSS-1E is an Indian navigational satellite operated by the Indian Space Research Organisation (ISRO) and the fifth spacecraft to be launched as part of the Indian Regional Navigation Satellite System (IRNSS) constellation. Catalogued by the United States Space Surveillance Network under NORAD ID 41241 and internationally designated 2016-003A, the satellite lifted off on 20 January 2016 and remains operational in a geosynchronous inclined orbit today. As one of seven satellites forming the IRNSS network — later rebranded NavIC (Navigation with Indian Constellation) — IRNSS-1E plays a role in providing positioning, navigation, and timing services across the Indian subcontinent and surrounding region.

Mission and Purpose

The IRNSS programme was conceived to give India an independent satellite-based navigation capability, reducing reliance on foreign systems such as the United States' GPS or Russia's GLONASS for critical civil and defence applications. The constellation was designed to serve users across India and an extended service area stretching roughly 1,500 kilometres beyond its borders, covering a region that includes the Indian Ocean, parts of Central Asia, and Southeast Asia.

IRNSS-1E joined a constellation that had been steadily assembled since the launch of the first satellite in the series, IRNSS-1A, making it the fifth incremental addition. Each successive satellite expanded the effective coverage and redundancy of the network, and IRNSS-1E continued that progression. The full seven-satellite IRNSS constellation was designed to provide a Standard Positioning Service available to civilian users and a Restricted Service — an encrypted signal — reserved for authorised and military users. The system transmits on L5 and S-band frequencies.

While the mission type for IRNSS-1E is not individually specified in publicly available cataloguing records, its role as a navigation payload within the IRNSS constellation is well established through the broader programme documentation released by ISRO. The satellite's current operational status is not confirmed in the catalogued data, though orbital tracking confirms it remains in orbit.

Orbit and Tracking

IRNSS-1E occupies an inclined geosynchronous orbit (IGSO), a configuration that distinguishes some of the IRNSS satellites from those placed in geostationary orbit. While a geostationary satellite maintains a fixed position above the equator as seen from the ground, an inclined geosynchronous orbit results in the satellite tracing a figure-eight ground track — known as an analemma — over a fixed longitude with each sidereal day. This apparent drift north and south of the equator is a direct consequence of the orbital inclination.

According to current tracking data, IRNSS-1E has an apogee of 35,869 km, a perigee of 35,719 km, and an orbital inclination of 33.2 degrees. The orbital period is approximately 1,436.1 minutes — very close to one sidereal day — which is precisely the condition that defines a geosynchronous orbit regardless of inclination. The relatively small difference between apogee and perigee indicates that the orbit is nearly circular, consistent with the requirements of a navigational satellite that must maintain predictable geometry relative to ground receivers.

The satellite is anchored at an orbital slot of 111.75 degrees East longitude, a position that keeps it over the Asia-Pacific region and within continuous view of the Indian subcontinent. This longitude was selected as part of ISRO's careful planning to achieve the geometric dilution of precision (GDOP) values needed for accurate positioning across the intended service area.

With a mass of 1,425 kg at launch, IRNSS-1E is a medium-class spacecraft by current standards. At geosynchronous altitude, it is not visible to the naked eye under ordinary circumstances, but it can be tracked by ground stations and catalogued observers using radar and optical means. Its NORAD catalogue entry (41241) allows it to be followed through publicly accessible two-line element (TLE) sets updated by the 18th Space Control Squadron and available on platforms such as this one.

Design and Operator

IRNSS-1E was designed and procured under the authority of the Indian Space Research Organisation, India's primary civilian space agency headquartered in Bengaluru. ISRO has served as both the developer and operator of the IRNSS programme from its inception, managing satellite design, launch coordination, and ground-segment operations through its own facilities, including the ISRO Telemetry, Tracking and Command Network (ISTRAC) and the dedicated IRNSS ground control infrastructure.

The satellite's manufacturer is not recorded in the public cataloguing data available for this entry. Consistent with ISRO practice for the IRNSS series, the spacecraft were built at ISRO's satellite integration facilities and launched aboard the organisation's own Polar Satellite Launch Vehicle (PSLV), which had by that point become a highly reliable workhorse for Indian space missions. The PSLV's proven capability with geosynchronous transfer trajectories made it the logical choice for positioning navigation satellites into their intended high orbits.

At 1,425 kg, the satellite falls within the range typical for the IRNSS series, which were built on ISRO's I-1K spacecraft bus — a platform developed domestically and used across several of the organisation's operational satellite families. The I-1K bus provides three-axis stabilisation, onboard power generation through solar panels, and the thermal management systems required for long-duration geosynchronous operations. The design lifespan for satellites of this class is generally around ten years, though actual service life can extend beyond that figure depending on propellant reserves and component health.

Current Status and Significance

IRNSS-1E holds a meaningful place in the history of India's space and technological development. Its launch in January 2016 came during the final stages of completing the seven-satellite IRNSS constellation, a milestone that India achieved within a relatively short programme timeline and entirely with domestic launch capability. The completion of the constellation gave India membership in a small group of nations and regional organisations — alongside the United States, Russia, Europe, China, and Japan — capable of operating an independent satellite navigation system.

The satellite's ongoing presence in orbit at 111.75 degrees East also reflects a broader story about the resilience of space infrastructure. In 2025, IRNSS-1E was expected to be relieved from active duty at its orbital slot by NVS-02, the second satellite in the next-generation NavIC Satellite (NVS) series, which was intended to modernise and expand the constellation's capabilities. However, following the failure of NVS-02, those transition plans could not be executed as scheduled, and IRNSS-1E continues to hold its orbital position. This outcome underlines a recurring reality in satellite operations: ageing spacecraft often find themselves in extended service when planned replacements encounter technical difficulties, and a satellite's designed end-of-life date can bear little resemblance to its actual operational retirement.

The broader IRNSS/NavIC programme, of which IRNSS-1E is a constituent part, has matured into an operationally significant system used for maritime navigation, disaster management support, vehicle tracking, and other location-based services across South Asia. The programme also carries strategic relevance, as India's defence and security establishment benefits from an independent navigation infrastructure not subject to the access policies of foreign operators.

IRNSS-1E itself has now been in orbit for more than nine years, outlasting its originally envisioned service window and demonstrating the longevity that can be achieved by well-engineered geosynchronous spacecraft. Whether the satellite continues to provide active navigational signals or has transitioned to a reserve or standby role is not confirmed in the public cataloguing record, but its orbit remains stable and it continues to be tracked as an active payload.

Observing IRNSS-1E

At geosynchronous altitude — roughly 35,800 km above the Earth's surface — IRNSS-1E is far too faint and distant to be observed with the naked eye under any practical circumstances. Even with modest amateur telescopes, geosynchronous satellites present a considerable challenge, as they appear essentially stationary against the star field and are typically around magnitude 10 to 14 depending on the spacecraft's reflectivity and the observer's equipment.

Dedicated satellite observers using large-aperture telescopes and precise pointing data derived from current TLE sets can locate IRNSS-1E near its nominal longitude of 111.75 degrees East at a declination that varies seasonally due to the 33.2-degree orbital inclination. Its apparent motion across the sky will be slow relative to low-Earth-orbit objects, and observations are best attempted in the hours around twilight when the satellite is illuminated by sunlight while the sky background remains dark enough for contrast. The orbital parameters listed on this page provide the basis for generating accurate prediction data through any standard satellite-tracking tool.