IRNSS 1J, 1K (NVS 01, 02)

IRNSS [ISRO]

Navigation with Indian Constellation is the operational name of the Indian Regional Navigation Satellite System (IRNSS), also known as NavIC. It offers precise real-time positioning and timing services over India and an area encircling the Indian Mainland for about 1500 km. There are seven satellites in GEO (Geostationary Orbit) at 32.5°, 83° and 131.5° East, while the other four satellites are in an inclined geosynchronous orbit with an inclination of 29° with longitude crossing at 55° and 111.75° East.

The first of the second-generation navigation satellite series, NVS-01, will maintain the existing NavIC services while also introducing new L1 band services. The GSLV-compatible NVS-01 satellite is constructed based on the I-2K (I-2000) Bus. Its mass at liftoff is roughly 2232 kg. It carries payloads for navigation that operate in the L1, L5, and S bands. Two solar arrays that can produce up to 2.4 kW of power and a lithium-ion battery that can support the payload and bus load during an eclipse power the satellite. The satellite uses a three-axis body stabilised zero momentum system with reaction wheels, a unified bi-propellant propulsion system, and both passive and active thermal management. NVS-01 should have a mission life of more than 12 years.

The second-generation satellite series includes the L1 Navigation band and incorporates a locally developed Rubidium atomic clock as opposed to the first-generation satellite series. The L1 navigation band is well known for its interoperability with other GNSS signals and for offering PNT (Position, Navigation, and Timing) services to civilian users. The Space Applications Centre, Ahmedabad, developed the Rubidium atomic clock for use in space.

The navigation payload operates in L1, L5, and S bands and employs a Tri-band antenna. The heart of the navigation payload is the Rubidium Atomic Frequency Standard (RAFS), the atomic clock which acts as a stable frequency reference for the navigation payload.

The ranging payload consists of CXC transponder used for two-way CDMA ranging to facilitate precise orbit determination.