India is Close to Achieving Data Relay Technology for Space Applications

Article by Shantanu K. Bansal

The GSAT-29 satellite (featured above) was launched on 14 November, 2018. The GSAT-29 is a high-throughput communication satellite had something unusual with it. The ISRO website stated that GSAT-29 carries “an optical communication payload, for the first time, will be utilized for data transmission.”

The optical communication (or Laser communication) is used to communicate information like conventional radio payloads as a standard Radio Frequency (RF) apparatus shall do but are able to do so far more precisely, quicker and at a much higher rate compared to a normal RF system.

Outfitted with a laser communications package a satellite could beam an image to Earth within five minutes—and that’s aassumingg a modest optical transmission rate of 100 Mbps as compared to RF which uses an hour time for the same. This could be very beneficial for strategic operations.

For instance, today’s laser communications terminals are being designed to transmit at multi-Gigabit speeds, meaning that even high-definition images and other large data files can be sent from space at an unprecedented rate. Besides the speed another feature is that the laser communication is itself immune to any Eelectronic Warfare system hence cannot be intercepted.

This unique laser based optical communication is being tested for the first time by the ISRO on the GSAT-29 which worked as the testing platform for India’s future Data Relay satellite.

“Data transmission through optical communication link would help to realise future advanced satellites and would be used for Satellite-to-satellite communication” as stated by ISRO Chief Dr. K. Sivan while the launch of GSAT-29 satellite.

India is very close on its own Tracking and Data Relay Satellite (TDRS) which can provide data services in minutes instead of hours, allowing the user instant access to data from Lower Earth Orbit (LEO) satellites where almost 80% spy satellite operates.

This makes end-to-end use in LEO considerably simplified by transmitting data through space-based infrastructure instead of ground stations, which is more time-consuming.

The IRDSS Programme is on Track

The ISRO announced that it aims to launch its own TDRS (satellite) for space communication purposes, called the Indian Data Relay Satellite System (IDRSS).

The first of these two satellites will be launched into low-Earth orbit by the end of 2020, ahead of the unmanned Gaganyaan test flight that will also carry a humanoid dummy onboard, laden with sensors. The launch of the satellite may see delay due to the coronavirus pandemic.

The second satellite was to be launched in 2021, before the manned mission is embarked upon in 2022, as decided in pre-pandemic era.

The IDRSS will be pivotal in maintaining communication with the astronaut crew and ground mission control at any given phase since being a bulky mission the effective communication with the crew and the systems is a prerequisite therefore IRDSS is an integral part of the Gaganyan mission besides the obvious strategic implications of such satellite, as explained.

The IRDSS is also necessary because ISRO has planned with many advanced LEO missions such as space station, space docking, and distant expeditions to the moon, Mars and Venus. The Indian Data Relay Satellite System (IDRSS) will track and be constantly in touch with Indian satellites, in particular, those in low-earth orbits (LEO) which have limited coverage of earth.


  • Shantanu K. Bansal

    Founder of IADN. He has more than 10 years of experience in research and analysis. An award winning researcher, he writes for the leading defence and security journals, think-tanks and in-service publications. He is a senior consultant at the Indian Army Training Command (ARTRAC), Shimla. Contact him at:

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