The GSLV-D1 mission was India’s first attempt at launching a satellite using the Geosynchronous Satellite Launch Vehicle (GSLV), marking a significant step in the country’s space ambitions.

Launch Date & Time: 18 April 2001, 15:43 IST

Launch Site: Satish Dhawan Space Centre (SHAR), Sriharikota, Andhra Pradesh

Launch Vehicle: GSLV-D1 (Geosynchronous Satellite Launch Vehicle, Developmental Flight 1)

Payload: GSAT-1 (Experimental Communication Satellite)

Satellite Mass: 1,540 kg

Planned Orbit: Geosynchronous Transfer Orbit (GTO)

GSLV-D1 Vehicle Configuration

The GSLV-D1 was a three-stage launch vehicle, developed to place satellites into geostationary orbit (GEO).

First Stage (Solid Rocket Motor + Liquid Strap-ons)

Core stage: S-125 solid rocket motor

Four liquid strap-on boosters (L40H engines)

Second Stage (Liquid Propellant)

Engine: Vikas engine (powered by UDMH + N2O4)

Third Stage (Cryogenic Upper Stage)

Used a Russian-built KVD-1 cryogenic engine

Fueled by Liquid Hydrogen (LH2) and Liquid Oxygen (LOX)

The GSLV-D1 successfully lifted off and reached its intended altitude.

However, GSAT-1 failed to reach its final geostationary orbit due to an underperformance of the cryogenic upper stage, leading to an elliptical orbit instead of a circular geostationary one.

GSAT-1 was still able to perform some communications tests, but it could not be used operationally.

Significance of GSLV-D1

First Indian rocket designed for GEO satellite launches

First Indian launch vehicle to use a cryogenic upper stage (though Russian-built, as India’s indigenous cryogenic engine was still under development)

Despite the partial failure, the mission was a crucial learning experience for ISRO, leading to improvements in later GSLV missions.

The lessons from GSLV-D1 helped ISRO achieve full success in the GSLV-D2 mission (2003) and later develop India’s indigenous cryogenic engine, first successfully flown in GSLV-D5 (2014).