In the eleventh flight of Polar Satellite Launch Vehicle (PSLV) conducted from Satish Dhawan Space Centre (SDSC, SHAR), Sriharikota on April 23, 2007, PSLV-C8 successfully launched the 352 kg Italian astronomical satellite, AGILE, into a 550 km circular orbit, inclined at an angle of 2.5 deg to the equator.

PSLV-C8 mission was unique in many respects. In this mission, PSLV was flown, for the first time, without the six strap-on motors of the first stage. Also, for the first time, PSLV launched a satellite into an equatorial circular orbit of 550 km. PSLV-C8 was the first major commercial launch of PSLV, the contract for which was won against stiff international competition.

Along with the Italian satellite, AGILE, an Advanced Avionics Module (AAM) from ISRO, weighing 185 kg, to test advanced launch vehicle avionics systems like mission computers, navigation and telemetry systems, was also flown on PSLV-C8. With ten successful flights so far, PSLV has emerged as the workhorse launch vehicle of ISRO.

After the final count down, PSLV-C8 lifted off from the Second Launch Pad (SLP) at SDSC SHAR at 15:30 hrs Indian Standard Time (IST ) with the ignition of the core first stage. The important flight events included the separation of the first stage, ignition of the second stage, separation of the payload fairing at about 116 km altitude after the vehicle had cleared the dense atmosphere, second stage separation, third stage ignition and third stage separation, fourth stage ignition and fourth stage cut-off. AGILE was placed in orbit about 1371 sec after lift off.

AGILE undergoing prelaunch tests at Satish Dhawan Space Centre (SDSC) SHAR

With a much lower payload mass and the low inclination of the orbit in which  AGILE was to be placed, PSLV-C8 was launched in ‘core alone’ configuration without strap-ons. Also, the propellant in the fourth stage had been reduced by about 400 kg compared to the previous PSLV flight. The core-alone PSLV-C8 had a lift-off mass of 230 tonne.

Since its first successful launch in 1994, PSLV has launched eight Indian remote sensing satellites, an amateur radio satellite, HAMSAT, a recoverable space capsule, SRE-1, and six small satellites for foreign customers into 550-800 km high polar Sun Synchronous Orbits (SSO). Besides, it has launched India’s exclusive meteorological satellite, Kalpana-1, into Geosynchronous Transfer Orbit (GTO) and now, this versatile vehicle has launched a satellite from abroad into a low earth equatorial orbit. PSLV will also be used to launch India’s first spacecraft mission to moon, Chandrayaan-1, during 2008.

Advanced Avionics Module mounted on the lower portion of PSLV-C8’s Dual Launch Adapter

Hoisting of AGILE during its integration with PSLV-C8

In its standard configuration, the 44 m tall PSLV has a lift-off mass of 295 tonne. It is a four-stage launch vehicle with the first and the third stages as well as the six strap-ons surrounding the first stage using HTPB based solid propellant. PSLV’s first stage is one of the largest solid propellant boosters in the world. Its second and fourth stages use liquid propellants. PSLV’s bulbous payload fairing has a diameter of 3.2 metre. The vehicle has S-band telemetry and C-band transponder systems for monitoring its health and flight status respectively. It also has sophisticated auxiliary systems like stage and payload fairing separation systems.

AGILE
AGILE is an X-ray and Gamma ray astronomical satellite of the Italian Space Agency (ASI), Rome. The design, development and fabrication activities of the satellite were led by Carlo Gavazzi Space, Milan, Italy. The launch was arranged by Cosmos International through Antrix Corporation. The satellite carries scientific instruments capable of studying distant celestial objects in X-ray and Gamma ray regions of the electromagnetic spectrum.