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Fifty years ago, on April 19, 1975, a Soviet rocket carrier, Interkosmos, successfully launched Aryabhata into space from the Kapustin Yar cosmodrome. This event marked a pivotal moment, launching India's satellite odyssey and setting the stage for the Indian Space Research Organisation's (ISRO) remarkable journey in space exploration. Today, ISRO boasts a fleet of 131 satellites, with 51 currently orbiting Earth, a testament to the vision and dedication that began with Aryabhata. Named after the ancient Indian astronomer, Aryabhata represented the nation's first indigenously built satellite, a symbol of self-reliance and technological prowess. The initial signals from Aryabhata were received just 30 minutes after launch at the Indian ground station in Sriharikota, Andhra Pradesh, located approximately 5,000 kilometers from the Soviet launch complex. This immediate success underscored the meticulous planning and engineering that went into the project.
Before Aryabhata, ISRO had gained valuable experience through the Rohini Sounding Rocket Experiment and other experiments conducted since 1963 at the Thumba Equatorial Rocket Launching Station in Thiruvananthapuram, established by the visionary Vikram Sarabhai. However, the ambitious goal of designing and building India's own Satellite Launch Vehicle (SLV) remained on the drawing board. This necessitated collaboration with established spacefaring nations with existing satellite launching facilities. In a significant step towards realizing this vision, India signed an agreement with the Academy of Sciences of the Union of Soviet Socialist Republics (USSR) on May 10, 1972. The USSR had initiated the Interkosmos program to foster joint research endeavors with other countries. The agreement stipulated that an Indian-made satellite would be launched from a Soviet cosmodrome within two to three years. This collaboration proved crucial in overcoming the challenges posed by international politics.
The international landscape at the time presented significant hurdles. India's discreet conduct of its first nuclear test at Pokhran in May 1974 triggered sanctions from the United States, impeding the transfer of knowledge and technology that could have aided in the development of Aryabhata. Recognizing the potential for increased international scrutiny, Pramod Kale, former director of the Vikram Sarabhai Space Centre, even suggested renaming the Indo-Soviet Satellite Programme to the Indian Scientific Satellite Programme to attract less attention to India's burgeoning space ambitions. This highlights the delicate geopolitical considerations that influenced the project's development and execution.
The location of ISRO's initial operations near Thiruvananthapuram, chosen for its proximity to the equator, proved to be less than ideal for establishing the necessary infrastructure for advanced space activities. The coastal environment and frequent saltwater splashes hindered the construction of clean room facilities and specialized instrumentation. As Pramod Kale explained, this led to the decision to relocate the activities to Bangalore, which offered a more conducive environment and access to established institutions such as Hindustan Aeronautics Limited (HAL). The establishment of the Isro Satellite Systems Project at Peenya village, then known as Asia's largest chain of small and medium-scale industries producing engineering and electronics goods, provided the necessary ecosystem for the project to thrive.
Under the leadership of U R Rao, a pioneer in India's satellite technology, a dedicated team of 200 engineers and scientists embarked on the challenging task of designing and building Aryabhata at Peenya. The spacecraft's unique quasi-spherical shape, with 26 sides and a weight of 358 kg, reflected innovative design principles. Aryabhata was equipped with three scientific experiments: X-ray astronomy, solar neutrons and gamma rays observation, and upper atmosphere studies. The distinctive structure of Aryabhata piqued the curiosity of local residents in Peenya. S Radhakrishnan, who worked at a factory in Peenya during the 1970s, recalled seeing ISRO engineers conducting tests and experiments in shed 'A,' though the exact nature of their work remained a mystery to him and his colleagues. He also remembered glimpses of then-Prime Minister Indira Gandhi, who made several visits to Bangalore to inspect Aryabhata's progress.
The development of Aryabhata required the establishment of specialized infrastructure within the shed in Peenya. This included electronics laboratories, a clean room for the final assembly of the satellite, thermal laboratories, control and stabilization laboratories, antenna testing facilities, and workshop and drafting sections. For approximately 30 months, ISRO teams dedicated themselves to developing prototypes, conducting rigorous testing, and ensuring the highest levels of reliability. These tests included qualification in a thermo-vacuum chamber, vibration and shock tests. To simulate the conditions of spaceflight, the satellite model was even transported by helicopter over Sriharikota during January 1975. The helicopter hovered at various distances and altitudes from the ground station, allowing engineers to verify the two-way communication link between the satellite and the ground telemetry station under simulated power levels.
In addition to helicopter-based testing, the instruments for the scientific experiments underwent rigorous testing on a balloon at an altitude of 25 kilometers in May 1973. The communication link was tested at a simulated distance of 400 kilometers. During the first quarter of 1975, the final fabrication phase of two flight models was completed, along with the complete integration and testing of the actual flight model. Simultaneously, in Bangalore, ground-based support and tracking systems, including telemetry, telecommand, and communication units, were being prepared. The entire ground station's functionality was rigorously tested using a helicopter-borne satellite model and simulating the transmitter power levels for the maximum range the satellite would have during its orbit. This ensured that the ground station could effectively receive telemetered data and send commands to the satellite. A Mission Operations and Control Centre was established at Peenya to coordinate the commanding and data-gathering program from various ground stations.
Despite the eventual failure of the three scientific experiments onboard Aryabhata due to a power failure, the satellite's technological experiments proved invaluable. These experiments focused on using the onboard telecommand system and the transmitter-receiver for data transmission between stations using the satellite as a node. These technological advancements laid the foundation for future satellite communication systems.
The legacy of Aryabhata extends far beyond its initial mission. Fifty years later, satellite-based communication has become ubiquitous in India and around the world. The foundations of this technology in India can be directly traced back to Aryabhata and ISRO's pioneering efforts. The first voice transmission of a recorded speech was transmitted from Sriharikota to Bangalore via Aryabhata. This demonstration highlighted the potential for high-quality satellite communication. Further experiments involved the transmission of electrocardiogram (ECG) signals, showcasing the unlimited possibilities that satellite communication could offer in the future of healthcare and remote monitoring. The India Meteorological Department in Pune collaborated with ISRO to establish a weather data gathering platform, collecting wind speed, temperature, and wind direction data from standard data collection points. This early application of satellite technology for weather monitoring paved the way for more advanced forecasting systems.
Aryabhata, composed of over 12,000 electronic components, 20,000 solar cells, and more than 25,000 interconnections, served as a powerful demonstration of India's indigenous capabilities in the realm of space technology. It showcased the nation's ability to undertake the structural designing of a space-worthy satellite, fabricate and test it, develop thermal and power control systems, and establish a comprehensive ground station along with sophisticated data processing systems. Aryabhata stands as a testament to the vision, dedication, and ingenuity of Indian scientists and engineers, marking a significant milestone in India's journey to becoming a major player in the global space arena. Its success inspired generations of scientists and engineers, and its legacy continues to shape India's space program today. The journey that began with Aryabhata has transformed India into a spacefaring nation capable of launching sophisticated satellites, conducting complex scientific missions, and contributing significantly to our understanding of the universe. From communication and navigation to weather forecasting and remote sensing, the applications of space technology are deeply embedded in modern life, and India's contributions to this field are a direct result of the foundation laid by Aryabhata and the visionaries who made it possible. The future of India's space program is bright, with ambitious plans for lunar and planetary exploration, advanced satellite systems, and innovative technologies that will continue to benefit society and inspire future generations. The spirit of Aryabhata lives on, driving India's relentless pursuit of knowledge and exploration in the vast expanse of space.