M A I N   N E W S

Edusat placed in orbit

New Delhi, September 26
Edusat, which was launched by GSLV from the master control facility (MCF), Hassan, was placed near the geosynchronous orbit after the third and final orbit-raising operation conducted at 8.21 am on September 24.

The manoeuvre was completed by firing liquid apogee motor (LAM) on board the satellite for a duration of 2 minutes and 15 seconds, an official release said today.

With this operation, the satellite has achieved an orbital period of 23 hours and 46 minutes and is continuously within radio visibility of the MCF.

It is now located at 61° east longitude, and is drifting towards its orbital slot of 74° east, at a rate of 2.54° per day. It will reach its first in-orbit test slot by October 2.

After the completion of the third apogee motor firing, the east-side antenna of the satellite was also deployed successfully. This antenna is intended for transmitting and receiving Ku-band signals with multiple spot-beam coverage.

Three-axes stabilisation of the satellite and its west side antenna deployment were carried out yesterday at 7 am and 2.15 pm, respectively.

This antenna is intended for transmitting and receiving extended C-band signals.

Besides two deployable antennas, the satellite has one body-mounted antenna meant for transmitting and receiving Ku-band signals with the national coverage beam.

In the three-axes stabilised mode, the satellite is locked onto earth continuously through its optical sensors and maintains proper orientation to look at the earth in a stable manner.

The momentum wheels onboard the satellite spinning at 4,500 revolutions per minute provide gyroscopic stiffness and maintain three-axis stabilisation.

Edusat was launched by GSLV on September 20 into a geosynchronous transfer orbit (GTO) of 180 km perigee (nearest point to the earth) and 36,000 km apogee (farthest point to the earth) with an orbital inclination of 19.3° with respect to the equatorial plane.

Subsequently, LAM was fired in three stages to take the satellite to its present near geosynchronous orbit with an inclination of almost zero degree with respect to the equator.

The LAM was fired for a total duration of 94 minutes.

A total velocity of 1.66 km per second was added by LAM at the apogee point of the orbit to take the satellite from GTO to near GSO.

Edusat had 1,128 kg of propellants at the time of its injection into GTO by GSLV. After orbit-raising operations, it now has 300 kg of propellants remaining which is sufficient to maintain the satellite in its orbit and control its orientation during its design life of 7 years.

The communication transponders of the satellite will be tested during the next three weeks and it is expected to be ready for use in two months. — UNI