Arianespace and the Indian Space Research Organisation successfuly lifted the first in the third generation of Insat satellites on 22 March at 04:58 Indian time. The Arianespace-505 launcher had an additional payload in the Asiastar satellite which was launched for digital radio service, WorldSpace.
Asia Star was first injected into orbit 28 minutes after lift-off, and seven minutes later, INSAT-3B was injected (in a three-axis stabilised mode into a Geo-synchronous Transfer Orbit – GTO) with a perigee of 560 km and an apogee of 35,770 km and an inclination of 7 degree with respect to the equator.
The satellite is at present orbiting around the earth with a period of 10.64 hours. The Insat Master Control Control Facility (MCF) at Hassan in Karnataka acquired the telemetry signal from Insat-3B at 5.30 (IST) three minutes prior to its separation from the launcher.
On separation of the satellite from the composite adopter, satellite health checks were conducted and a series of commands issued from the MCF so as to orient its earth-viewing face towards earth. The outermost panel of the stowed solar array on the south side was also oriented towards the sun to start generating the electrical power required by the satellite during its transfer orbit phase.
The calibration of the gyros on board the satellite has also been carried out. The operations were completed in about (100 minutes). Insat-3B is being tracked, apart from MCF, Hassan, by INTELSAT Organisation’s ground stations at Perth (Australia), Fucino (Italy) and Lake Cowichan (Canada).
The satellite will go out of the visibility of MCF, Hassan at about 03:36 pm (IST) this afternoon and will come within the radio visibility of MCF, Hassan at 02:36 am tomorrow.
The satellite’s orbit is being precisely determined by continuous ranging from the participating TTC stations. The orbit raising operations on INSAT-3B will be carried out by firing the 440 Newton liquid apogee motor on board in stages till the satellite attains its final geostationary orbit, about 36,000 km above the equator.
The first Apogee Motor Firing (AMF-1) is planned during the third transfer orbit tomorrow (March 23, 2000) at about 07:30 am IST. The satellite has about 1,100 kg of propellant (Mono-Methyl Hydrazine – MMH and Mixed Oxides of Nitrogen – MON-3) for orbit raising operations as well as for station keeping and in-orbit attitude control for the duration of its designed life of 10 years.
When the satellite reaches near geo-stationary orbit, deployment of two solar panels and the two antennas will be carried out and the satellite put in its final three-axis stabilised mode. The payloads will be checked out before commissioning the satellite. The deployment of the solar array and the two antennas will be carried out after the satellite attains near geo-synchronous orbit.
Insat-3B will be collocated with INSAT-2E at 83 deg East longitude. It may be noted that Insat satellites now occupy four slots — Insat-2B and Insat-2C are collocated at 93.5 deg (E) longitude, INSAT-1D and INSAT-2A are collocated at 74 E longitude and Insat-2DT is located at 55 E longitude besides Insat-2E at 83 deg East longitude.
Insat-3B is primarily intended for business communication, developmental communication and mobile communication. The communication payload provides 12 extended C-band channels, each having a bandwidth of 36 MHz. The Ku-band payload provides three channels, having a bandwidth of 77/72 MHz. The Mobile Satellite Service transponders operate in C/S band frequencies. Compared to INSAT-2C/2D, the power of extended C-band transponders on board INSAT-3B has been increased from 10 W to 15 W and that of Ku-band from 20 W to 55 W.
Once commissioned, INSAT-3B is expected to further boost the Very Small Aperture Terminal (VSAT) services. The major VSAT users include banking and financial institutions, stock markets, white goods sector, fast moving consumer goods sector and medium to heavy engineering companies. Several public and private sector units have established dedicated closed-user group networks for their in-house applications. At present seven transponders from INSAT-2B and INSAT-2C are being used for these applications and INSAT-3B will almost double the transponder capacity for these services. For the first-time Ku-band frequencies will also be used for VSAT services, which enables use of smaller ground terminals.
INSAT-3B will provide the first set of transponders for Swaran Jayanti Vidya Vikas Antariksh Upagraha Yojana (Vidya Vahini) which had been announced by the Prime Minister on 15 August 15 1998. These transponders will be used exclusively for interactive training and developmental communication and will be a further extension of the present Training and Developmental Communication Channel of Insat that is being used by several agencies.
Tele-medicine is also expected to be introduced that will help in remote iagnostics and extension of super special hospital treatment to the rural population. INSAT-3B Mobile Satellite Service (MSS) has forward link channel in C X S band and return link in S X C band. MSS can support portable terminals and carry voice, fax or data. It also supports messaging service using reporting terminals.
