Launched on 5th May 2005 10:15 AM from Sri Hari Kota Launch Range (SHAR), hamsat was a co-passenger along with another of ISRO's satellite known as Cartosat I on a Polar Satellite Launch Vehicle (PSLV). HAMSAT or VUSAT as hams call it, is Indian Space Research Organisation's (ISRO) theme-based micro satellite.

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The HAMSAT micro satellite is India's contribution to the international community of Amateur Radio operators.  This effort is also meant to bring ISRO's satellite services within the reach of the common man and popularize space technology among the masses.

       

        It is a cuboidal structure of 630mm X 630mm X 550mm with a mass of about 42.5 Kg.  It has aluminium honey-comb structure with passive thermal control. Hamsat will be flown in a near-circular polar Low Earth Orbit(LEO). Body mounted solar panels and COTS (Commercial Off The Shelf) Lithium-Ion batteries are the main source of power. The satellite spins at a rate of about 4rpm with the spin axis orientation being ± 3degs. Spin stabilization is provided with on-board autonomy.

Tri-axial magnetometer and Twin Slit Sun Sensor with magnetic torquers act as actuators providing the required inputs to the Bus Electronics.  Bus Electronics consists of  MAR31750 processor.  This system also provides for attitude control, telemetry and telecommand for the satellite.

 

Communication for the satellite is on VHF (137MHz for TM and 149MHz for TC). There are two payload transponders - Indian and Dutch.   Dutch transponder was delivered by William Leijenaar, PE1RAH. Both these operate in Mode-B with 435.25MHz uplink and 145.90MHz downlink. Indian transponder is identified by an un-modulated carrier on 145.936MHz and Dutch transponder has a CW signal on 145.860MHz. The output power is about 30dBm. Bandwidth is 60KHz for the Indian transponder and 50KHz for the Dutch transponder. Only one transponder is `on' at a time. Antennae are turnstile are common for TM/TC and payload transponders.

 

       

HAMSAT Specifications
Physical	630mm X 630mm X 550mm Cuboid
Mass	42.5 Kg
Orbit	Near Circular Polar Low Earth Orbit
Structure	Aluminium Honeycomb Structure
Power	Body mounted Gallium Arsenide Solar Panels, Lithium Ion Battery
Stabilisation	Spin Stabilised (4 +/-  0.5 RPM)
Antennas	UHF Turnstile, VHF Turnstile
Transponder Uplink	435.250 Mhz
Transponder Downlink	145.900 Mhz
Bandwidth	60 KHz
Transmitter Ouput Power	1 watt
Modes of Communication	CW, SSB, FM

Apart from MAR31750 processor-based Bus Electronics, COTS Li-Ion batteries and Ga-As solar panels, other new technologies incorporated are micro strip VHF 180deg. hybrid coupler, micro strip 4-way power divider and negative-B dot law for attitude control.

 

        Programmed tracking of Hamsat is being carried out by ISRO's two stations at Bangalore and Lucknow.