INSAT-4A: India's Pioneering High-Capacity Communications Satellite
The INSAT-4A marked a significant milestone in India's space capabilities, serving as the inaugural spacecraft in the INSAT-4 series. Designed specifically for advanced communications, this satellite expanded the nation's ability to transmit data and broadcast services across a vast geographical area. At the time of its deployment, it held the distinction of being the heaviest satellite ever produced by India.
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Key Facts
- Mission Type: Communications
- Operator: INSAT
- Launch Date: December 21, 2005
- Operational Lifespan: 13 years, 9 months, and 29 days
- Orbital Position: 83° East (Geostationary)
- Manufacturer: ISRO (Indian Space Research Organisation)
Technical Specifications and Design
Built on the I-3K bus (the structural framework of the satellite), the INSAT-4A was engineered for durability and high power output. With a launch mass of 3,081 kilograms and a dry mass of 1,386 kilograms, the spacecraft measured 2.8 x 1.7 x 2.0 meters. To support its complex communication payloads, the satellite utilized a power system capable of generating 5,922 watts.
Launch and Deployment
The spacecraft was launched on December 21, 2005, at 22:33 UTC from the Kourou ELA-3 launch site. The mission was executed by Arianespace using an Ariane 5GS rocket. Upon reaching space, the satellite was positioned in a geostationary orbit—an orbit where the satellite matches the Earth's rotation, appearing stationary from the ground—at the 83° East slot, sharing the position with INSAT-2E and INSAT-3B.
Communication Capabilities
The primary purpose of INSAT-4A was to provide robust communication services using two distinct frequency bands. The satellite was equipped with a total of 24 transponders (devices that receive a signal and retransmit it on a different frequency) with a bandwidth of 36 megahertz.
- Ku-band: Featuring 12 transponders, this band was specifically designed to provide coverage over the Indian mainland.
- C-band: Featuring 12 transponders, this band provided coverage over a more extended geographical area.
The technical performance was supported by Traveling Wave Tube Amplifiers (TWTA), providing power levels of 140 and 63 watts, with an Equivalent Isotropically Radiated Power (EIRP) of 51 and 38 dbW respectively.
Mission Summary Table
| Parameter | Detail |
|---|---|
| COSPAR ID / SATCAT No. | 2005-049A / 28911 |
| Launch Mass | 3,081 kg |
| Power Output | 5,922 Watts |
| Orbital Regime | Geostationary (83° E) |
| Planned Duration | 12 Years |
| Actual Duration | 13 Years, 9 Months, 29 Days |
| Deactivation Date | October 21, 2019 |
End of Mission
After exceeding its planned 12-year lifespan, the INSAT-4A was officially deactivated on October 21, 2019. To ensure the safety of other active satellites in the geostationary belt, the spacecraft was moved to a graveyard orbit, a disposal orbit located above the geostationary region where defunct satellites are placed.
Frequently Asked Questions
What was the primary purpose of INSAT-4A?
INSAT-4A was a communications satellite designed to provide services via Ku-band and C-band frequencies, covering both the Indian mainland and extended regional areas.
Which rocket was used to launch INSAT-4A?
The satellite was launched by an Ariane 5GS rocket, contracted through Arianespace, from the Kourou ELA-3 launch site.
How long did INSAT-4A remain operational?
While the mission was planned for 12 years, the satellite achieved a total operational duration of 13 years, 9 months, and 29 days.
What is the difference between the Ku-band and C-band on this satellite?
The 12 Ku-band transponders were focused on providing coverage for the Indian mainland, while the 12 C-band transponders were used for a wider, extended coverage area.
What happened to the satellite after it was deactivated?
Following its deactivation on October 21, 2019, the spacecraft was moved to a graveyard orbit for disposal.