IRNSS-1B

IRNSS-1B is an Indian navigational satellite operated by the Indian Space Research Organisation (ISRO) and the second spacecraft to be launched as part of the Indian Regional Navigation Satellite System (IRNSS) constellation. Cataloged by the United States Space Surveillance Network under NORAD ID 39635 and designated internationally as 2014-017A, the satellite lifted off in April 2014 and remains in orbit today, contributing to India's effort to establish an independent, regionally focused satellite navigation capability. Its deployment followed closely after the first satellite in the series and marked a steady progression toward completing the full constellation of seven spacecraft that the program envisioned.

Mission and Purpose

The Indian Regional Navigation Satellite System was conceived to give India sovereign control over a navigation infrastructure serving the Indian subcontinent and surrounding regions, reducing dependence on foreign systems such as the United States Global Positioning System (GPS) or Russia's GLONASS. Like its predecessor IRNSS-1A, IRNSS-1B was designed as one of the foundational elements of this constellation, which was planned to comprise seven satellites in total.

Navigation satellites in the IRNSS program are intended to provide positioning, velocity, and timing services to users across India and extending into a surrounding region roughly 1,500 kilometers beyond the nation's borders. These services support a wide range of civilian and strategic applications, including terrestrial navigation, disaster management coordination, fleet tracking, precision timing for telecommunications networks, and maritime and aerial navigation assistance. The satellite carries both standard positioning services intended for civilian users and a restricted service for authorized users requiring higher accuracy and security.

The mission type and operational status of IRNSS-1B are not formally recorded in the satellite catalog consulted for this entry. However, given its role in a navigational constellation and the broader program context, the satellite's payload is consistent with the L5 and S-band signal transmission equipment that IRNSS satellites are known to carry to broadcast navigation signals to ground receivers across the service region.

IRNSS-1B was placed into a geosynchronous orbit on April 4, 2014, a day after its launch, following the apogee-raising maneuvers typical of satellites delivered initially to a transfer orbit by a launch vehicle. This orbital placement was deliberate: geosynchronous satellites at inclined orbits provide continuous or near-continuous visibility over specific geographic regions without the extensive ground segment infrastructure that a lower-orbit constellation would require.

Orbit and Tracking

IRNSS-1B occupies what is classified as an inclined geosynchronous orbit (IGSO), a variant of the standard geostationary configuration in which the satellite's orbital plane is tilted relative to the equatorial plane. While a true geostationary satellite maintains a fixed inclination of zero degrees and appears stationary above a single point on Earth, an inclined geosynchronous orbit results in an apparent figure-eight or analemma-shaped ground track as seen from the surface. This characteristic is shared by several other regional navigation satellites worldwide.

The satellite's current tracked orbital parameters reflect this configuration precisely. Its apogee stands at 35,891 kilometers, and its perigee is recorded at 35,697 kilometers, placing it in a nearly circular orbit at approximately geosynchronous altitude. The relatively small difference between apogee and perigee — less than 200 kilometers — confirms that the orbit is close to circular, as intended for a navigation satellite requiring predictable signal geometry. The orbital inclination is 28.9 degrees to the equatorial plane, which is the defining characteristic distinguishing it from a zero-inclination geostationary orbit.

The satellite's orbital period is approximately 1,436.1 minutes, which corresponds closely to Earth's sidereal rotation period. This synchrony means IRNSS-1B completes one orbit in roughly the same time that Earth completes one full rotation, ensuring that the satellite traces a repeating ground track each day. This repeating geometry is essential for a regional navigation system, because it allows ground users to rely on a predictable schedule of satellite visibility.

With a launch mass of 1,432 kilograms, IRNSS-1B falls within the class of medium-weight geostationary and geosynchronous satellites that ISRO's launch vehicles were developed to handle. The satellite was launched on April 3, 2014 (Eastern Daylight Time), with orbital insertion into geosynchronous orbit confirmed the following day. It remains in orbit as of the time this entry was compiled, with no decay or reentry recorded.

Design and Operator

IRNSS-1B was built and is operated by the Indian Space Research Organisation, the government space agency of India. ISRO, headquartered in Bengaluru, has been the driving force behind India's independent space program since its establishment and has developed a range of launch vehicles, Earth observation platforms, interplanetary missions, and navigation satellite systems. The IRNSS program represents one of ISRO's most strategically significant undertakings, aimed squarely at providing India with capabilities that were previously available only to nations operating global navigation satellite systems.

The manufacturer of IRNSS-1B is not specified in the available catalog data. ISRO's satellite fabrication facilities, including the U R Rao Satellite Centre in Bengaluru, have historically been responsible for constructing the spacecraft in this series, but this article limits itself to confirmed data and does not attribute manufacturing to a specific entity without verified sourcing.

The satellite has a recorded mass of 1,432 kilograms. At geosynchronous altitude, this class of satellite typically carries a combination of navigation payloads, ranging and integrity monitoring equipment, and the associated power generation and thermal management systems needed to sustain operations over a multi-year design lifetime. Solar arrays and onboard batteries supply power, while the spacecraft bus maintains attitude control and housekeeping functions necessary to keep the navigation antenna pointed toward the intended coverage area.

IRNSS-1B operates as a payload — that is, a functional spacecraft with an active mission purpose, as opposed to a rocket body or debris fragment. This classification in the NORAD catalog confirms it as an intentionally placed, operational-type object, regardless of its current specific operational status as recorded in public databases.

Significance and Context

The launch of IRNSS-1B in April 2014 was a meaningful milestone in the broader assembly of India's regional navigation architecture. As the second satellite in the seven-spacecraft series, it demonstrated ISRO's ability to maintain a cadence of launches necessary to build out a functional constellation within a manageable timeframe. Navigational constellations require a minimum number of simultaneously visible satellites before they can deliver useful positioning fixes to ground receivers; each successful launch brought the system closer to that operational threshold.

India's development of IRNSS, later rebranded as NavIC (Navigation with Indian Constellation), positioned the country alongside a small group of nations and regional bodies that operate their own satellite navigation systems. These include the United States (GPS), Russia (GLONASS), the European Union (Galileo), China (BeiDou), and Japan, which operates a regional augmentation system. India's decision to develop an independent system reflects both the strategic value of navigation sovereignty and the country's broader ambitions as a space-capable nation.

The inclined geosynchronous orbit chosen for IRNSS-1B and certain other satellites in the constellation is well suited to providing coverage at the latitudes that encompass the Indian subcontinent, which lies predominantly between roughly 8 and 37 degrees north. An IGSO satellite with a 28.9-degree inclination spends a significant portion of each day at elevated angles above the horizon as seen from these latitudes, improving signal availability and reducing obstruction by terrain or buildings. This geometric advantage complements the geostationary slots used by other satellites in the IRNSS design, creating a combined architecture that balances coverage area with signal quality.

IRNSS-1B's continued presence in orbit, years after its April 2014 launch, underscores the durability of geosynchronous spacecraft. At this altitude, far above the denser regions of the atmosphere, orbital decay is negligible over human timescales, and satellites can remain in their assigned orbital slots for decades unless actively deorbited or relocated. The satellite continues to be tracked and cataloged, maintaining its position in the international registry of space objects under its COSPAR designation 2014-017A.

For observers and analysts following India's space program, IRNSS-1B serves as a reference point for the country's growing proficiency in designing, launching, and operating complex navigation infrastructure. Its place as the second node in a system that now supports real-world navigation services across the Indian subcontinent reflects a sustained institutional commitment by ISRO and the Indian government to developing sovereign, resilient, and regionally significant space capabilities.