Throughout its service life, a satellite must be maintained in the correct attitude (i.e., pointing in the right direction). Attitude is controlled by one of three methods: "spin-stabilizing" the entire satellite, including the antennas; spinning the body of the satellite while the antenna platform is "despun," or counter-rotated, in order to point stably at some point on Earth; and maintaining "three-axis" stability of the entire satellite by means of an internal gyroscope and small thruster jets.

The successful launch of PSLV-C6 by ISRO is a history-making accomplishment with India achieving its first presence of amateur radio satellite in space.

Congratulations to the HAMSAT Team and Chairman ISRO. This achievement is due to tireless work of many Scientists, Engineers of ISRO, Hams in India and around the world, who have helped accomplish this momentous task.

HAMSAT's polar sun synchronous orbit is some 618 km above Earth. Among other capabilities, the 42.5 KG, 24-inch-cuboid microsat--equipped with a transmitter capable of up to 1 Watt output--will allow voice communication using FM, SSB and CW (Morse Code – Radio Telegraphy).

We count on this launch as a step forward in the development of our country and the whole south Asia region. Today, we are getting the capability of covering the Indian sub continent with a simple handheld transceiver and getting into the club of countries that possess ability to design, building, integration, testing and launching of amateur radio satellites.

We're really excited of the fact that this satellite program has made technology available to common man through amateur radio. We have established ourselves as capable to achieve our goals, encourage youth to experiment new technologies, help in providing communication during emergencies, help develop rural areas with amateur radio communications.

We would like to take this as a stepping stone for future development and hope ISRO would go further ahead, with the experience gained during the first launch to continue in building programs in amateur satellite communication.

Once again, Congratulations to ISRO and HAMSAT team for making Indian Hams proud with an indigenous amateur radio satellite.

S.Suri (VU2 MY)
Founder, Chairman - NIAR

Small satellites, which are cheaper and quicker to build, are also a low-risk way to test new technology.

HITCHHIKING ON the Polar Satellite Launch Vehicle (PSLV) earlier this month alongside the 1,500 kg Cartosat-1 earth observation satellite was a small box-like satellite weighing just over 40 kg. It was Hamsat, a microsatellite built by the Indian Space Research Organisation with the help of amateur radio operators (known as hams) in India and in the Netherlands. Acting as a relay station high up in the sky, the satellite gives hams an easy and reliable way to communicate across vast distances.

Hamsat is the smallest satellite ISRO has built in recent times. The last time it made such light-weight satellites was 20 years ago when it developed the Rohini series, which too weighed around 40 kg, to fly experimental spacecraft on India's first launch vehicle, the SLV-3. Since then, ISRO's operational satellites for communications and earth observation have grown bigger and heavier.

The first of the Insat-4 communication satellites that ISRO plans to launch in a few months' time will, at over three tonnes, be two and a half times heavier than the Insat-1 satellites launched in the 1980s. Similarly, Cartosat-1 is one and a half times heavier than the IRS-1A launched in 1988.

Low cost

There is now worldwide interest in small satellites as they are cheaper and quicker to build. Hence, they are a low-risk way to test new technology. The European Space Agency recently issued a press statement saying that Proba, a washing machine-size earth observation satellite launched on the PSLV in October 2001 as a one-year technology demonstrator, was continuing its high-quality performance. It was making "a big contribution to science." Images supplied by its cameras were being used by some 56 scientific teams for a range of applications from studying vegetation and water quality to assessing the productivity of vineyards.

Surrey Satellite Technology Limited (SSTL) in the United Kingdom, world leaders in small satellites, has created a `Disaster Monitoring Constellation' with four earth observation satellites that were built for Algeria, Nigeria, Turkey and the United Kingdom; a fifth satellite for China is to be launched later this year. With four satellites in orbit, the constellation is able to image every part of the Earth every day.

Hamsat is part of ISRO's efforts to benefit from small satellite technology. Hamsat was built in two years at a cost of just Rs.3 crores, according to K. Thyagarajan, who heads the small satellite programme at the ISRO Satellite Centre in Bangalore. As the satellite handles orbit-keeping functions autonomously, ground operators need to check the satellite only once every few days. One of the satellite's two transponders (which receives radio signals from ham sets and then relays them back to the ground) was supplied by a ham enthusiast in the Netherlands and Indian hams have been involved in the satellite's development and testing.

Hamsat spins at about four revolutions a minute to maintain stability while orbiting the earth. ISRO is developing the basic structure for small satellites weighing around 100 kg that do not need to spin. The 90 kg TWSAT is intended by ISRO as an earth observation satellite suitable for Third World countries. User terminals for receiving data from this satellite would be installed in Indian universities and some Third World countries, according to the Department of Space's annual report.

Hams in India and abroad are delighted with Hamsat. After Project OSCAR when a U.S. based group built and launched the very first amateur radio satellite in 1961, a number of such satellites have been put into orbit, observes Air Commodore (Retd.) V. Subramanian, president of AMSAT India. AMSAT India was formed in 2001 by Indian hams to promote the development and use of amateur radio satellites.

Hamsat has already become the most popular amateur radio satellite among Indian and foreign hams as it relays voice signals rather than the more sophisticated digital communications, says Pratap Kumar, secretary of AMSAT India. Anyone with a simple handset can access it and reach fellow hams up to a few thousand kilometres away. On the very first day Hamsat became available for use, he was able to contact a person in Malaysia, Mr. Kumar told The Hindu.

By N. Gopal Raj - The Hindu