The countdown for the launch of India's second geo-synchronous satellite launch vehicle, GSLV-D2, of the Indian Space Research Organization from Sriharikota begins on May 7 to carry the experimental communication satellite, GSAT-2, into the geo-synchronous transfer orbit.

Announcing this, ISRO chairman K Kasturirangan said on Monday that the launch windows of the second development test flight [GSLV-D2] would be kept open between 1658 and 1930 IST on May 8 for a smooth and perfect lift-off.

The 1,800kg GSAT-2 will be placed in the transfer orbit at 180km perigee [nearest point to earth] and 36,000km apogee [farthest point from earth]. The total duration for injecting the spacecraft into the transfer orbit from lift-off will be around 17 minutes.

"Dedicated teams have carried out a full dress rehearsal of the launch vehicle on May 4 that included separation of satellite simulation and integrated participation of vehicle specialists," Kasturirangan said.

The rocket's various stages have been validated by the vehicle, range, and satellite teams respectively at the Satish Dhawan Space Center in Sriharikota and the Master Control Facility at Hassan in southern Karnataka.

ISRO's ground stations in Canada, Italy and China will pick up the telemetry signals once the GSLV-D2 is fired from the Sriharikota launch pad in Andhra Pradesh, about 100km from Chennai.

ISRO's first experimental satellite (GSAT-1), carrying a payload of 1,540kg, had to be virtually abandoned after it was launched by the GSLV-D1 in April 2001. It failed to reach its designated slot in the geo-synchronous transfer orbit and drifted away.

"This time, we are taking all the precautions to ensure that GSAT-2 will reach its designated slot. Contingency plans are also in place to make the required maneuvers for parking the satellite in the transfer orbit," Kasturirangan said.

GSAT-2 will be positioned at 48 degrees east longitude in the geo-stationary orbit. It will carry 4 C-band and 2 Ku-band transponders, a mobile satellite service payload operating in S-band forward link and C-band return link.

As a piggyback, the satellite will also carry four more payloads to conduct major experiments in space such as:

Total Radiation Dose Monitor -- To compare the estimated radiation doses inside the satellite with the directly measured radiation doses, using a radiation sensitive field effect transistor.

Surface Charge Monitor -- To indicate the state of the charging environment in the vicinity of the spacecraft.

Solar X-ray Spectrometer -- To study the solar flare emission in 4KeV - 10MeV energy range, using the state-of-the-art semiconductor devices and phoswich scintillation detector.

Coherent Radio Beacon experiment -- To investigate the special structure, dynamic and temporal variations of the lonosphere and several aspects of equatorial electrodynamics.

ISRO will be using the Russian-made Cryogenic engine for firing the third stage to produce a thrust of 73.5kg Newton. It carries 12.6 ton liquid hydrogen and liquid oxygen.

After its launch into the transfer orbit, GSAT-2 will be taken to its final slot by firing the liquid apogee motor in phases. Its antenna and solar panels will be deployed subsequently.

Measuring 9.55m in length in its final in-orbit configuration, the satellite will be a 3-axis body, stabilized to use sun and earth sensors.

"GSLV is the most technologically challenging project undertaken so far under the Indian space program. The second test flight will revalidate the various systems and the improvements carried out since the first launch," Kasturirangan said.