INSAT-3B Launched
INSAT-3B, first satellite in the third generation INSAT-3 series built by ISRO, was successfully launched early this morning (March 22, 2000) by the Ariane-505 vehicle of Arianespace. The 128th flight of Ariane, carrying ISRO’s INSAT-3B and Asia Star of Worldspace, USA, satellites, lifted off at 04:58 hours IST early this morning (March 22, 2000) from Kourou, French Guyana in South America. The Asia Star was first injected into orbit 28 minutes after the lift-off, and 7 minutes later, INSAT-3B was injected in a 3-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 deg. with respect to the equator. The satellite is at present going round the earth with an orbital period of about 10.64 hours.
The INSAT Master Control Facility (MCF) at Hassan in Karnataka acquired the telemetry signal from INSAT-3B at 5.30 (IST) 3 minutes prior to its separation. Immediately after separation of the satellite from the composite adopter, satellite health checks were carried out and a series of commands issued from MCF so as to orient earth-viewing face of the satellite towards earth. The outermost panel of the stowed solar array on the south side of the satellite 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. For the first time, an indigenously developed titanium propellant tank, with special propellant management device that ensures bubble-free propellant supply under zero-G environment, has been employed.
The higher perigee height of 560 km at the time of injection by Ariane-5, compared to 200 km in earlier INSATs launched by Ariane-4, results in lesser propellant consumption for orbit raising operations — an equivalent of the propellant required for six months of in-orbit operation. 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 3-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 deg E longitude and INSAT-2DT is located at 55 deg E longitude besides INSAT-2E at 83 deg East longitude.
The satellite main body is a cuboid of 1.93 X 1.7 X 1.65 m and, with the two solar panels fully deployed in orbit, it will measure 14.7 m in length. The sun tracking, solar panels, with a total area of 23 sq m generate a 1.7 kW of power. A 24 Ah Ni-Cd battery supports the payload operations during eclipses. INSAT-3B, like all its predecessors in the INSAT series, is 3-axis body-stabilised using momentum/reaction wheels, earth sensors, sun sensors, inertial reference unit and magnetic torquers. It is equipped with unified bi-propellant thrusters. The satellite has two deployable antennas and three fixed antennas that carry out various transmit and receive functions. The antennas have a pointing accuracy of +/- 0.2 deg in pitch and roll axes and +/- 0.4 deg in yaw axis. The satellite uses passive thermal control system.
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 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 for interactive training and education. Tele-medicine is also expected to be introduced that will help in remote diagnostics and extension of super special hospital treatment to 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.
With ISRO Satellite Centre (ISAC), Bangalore, as lead centre, INSAT-3B was realised with major contributions from Space Application Centre (SAC), Ahmedabad, Liquid Propulsion System Centre (LPSC) at Valiamala and Bangalore, Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram and ISRO Inertial Systems Unit (IISU), Thiruvananthapuram. Besides, several industries in both public and private sectors have contributed to the realisation of INSAT-3B. MCF is responsible for initial and in-orbit operation of all INSAT satellites.
