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S.C. Tapde: Of Antennae, Telescopes and an Engineer for All Seasons

S.C. Tapde: Of Antennae, Telescopes and an Engineer for All Seasons

S.C. Tapde (right) in front of the 32-metre antenna being built for ISRO at Byalalu. He was visiting on behalf of ECIL. To the left is S. Ananthakrishnan, former observatory director of the GMRT, in the role of review committee member. Photo: S. Ananthakrishnan

On April 12, 2021, more than fifty current and past staff from premier research, development and design organisations across the country gathered virtually at the National Centre for Radio Astrophysics (NCRA), Pune, for an online meeting in memory of Suresh Chandra Tapde. A few days after the customary thirteen, the meeting nonetheless marked the transition from mourning to acceptance, remembrance and, in this case, celebration of a life of singular achievement.

Tapde, as he was universally known, played a key role in some of the proudest space communication and astronomy initiatives in independent India. His journey started in the late 1960s, when he joined the project to build the country’s first indigenous large antenna for satellite communication at Arvi, north of Pune. This dish was nearly 30 metres in diameter – a good size even by today’s standards.

In 1977, he moved to the challenging 2.3-metre optical telescope project of the Indian Institute of Astrophysics (IIA) at Kavalur, midway between Bengaluru and Chennai. He spent an entire decade helping build it – the first large optical telescope to be fully made in India. It remains the largest in this category and was the workhorse for the Indian optical astronomy community for several decades.

After completing this project, he moved on in 1986 to what was surely his greatest challenge: the construction of the Giant Metrewave Radio Telescope (GMRT) at Khodad, a village off the Pune-Nashik highway. This was planned as an array of thirty 45-metre-wide antennae of an innovative but unproven design – the brainchild of Govind Swarup and given shape by Tata Consulting Engineers (TCE). The ambition was unprecedented, to achieve world-class performance within an extremely tight budget.

After it was finally commissioned in 2000, the GMRT was and remains one of the most sensitive radio telescopes in the world. Speakers at the memorial meeting recounted witnessing sparks fly between Swarup and Tapde and fearing the consequences for the GMRT project. But to the great credit of both men, these sparks, instead of setting off an inferno, lit a bright flame that continues to shine today.

Also read: Remembering Govind Swarup – Astronomer, Builder, Leader

One stringent test of the person and the work is what happens after retirement. As the reminiscences unfolded in the meeting, it became clear that Tapde’s superannuation in the year 2000 only cemented his position as the go-to expert for engineering projects linked to astronomy and space. These included the 32-metre deep space antenna for the Indian Space Research Organisation (pictured above) and MACE, the unique multi-mirror steerable gamma-ray telescope built for the Bhabha Atomic Research Centre (BARC).

He also played an important role in the project management board of the 3.6-metre optical telescope at Devasthal, even in declining health. In every case his counsel was sought by people who already knew him intimately, often people he had mentored earlier. They valued his extensive knowledge and experience, sharp and quick technical insight and ability to think out of the box. Equally important was the rare ability to listen closely to everyone, to call a spade a spade and yet not give offence.

Tapde would find the best way forward drawing on all inputs, and more often than not, he had the last word in the numerous meetings he attended. These skills were surely honed in the projects he had managed before retiring. The label of “manager” does poor justice to his role and contributions, especially his mentorship of a whole generation of engineers across a range of projects.

Architecture has been described as “frozen music”. In contrast, we have the restless machines powering our equally restless movement on land, sea and air. Telescopes and antennae fall between these extremes. When still, they rise majestic, like the epitome of architecture – yet they exist to move, usually slowly, to follow a distant object in the

heavens or track a spacecraft on its way to the Moon or Mars. The movement has to be smooth and precise, preserving the geometry and integrity of the reflecting surface that brings the radiation into focus. When high winds threaten, the same structure has to swing quickly to a safe position and, for optical telescopes, seek shelter behind a large movable dome.

All this is and has to be built to last many decades. Their builders draw on diverse branches of engineering to fulfil these goals – civil, mechanical, electrical, control, electronics, hardware and software. In theory, the person entrusted with such a project is like the conductor of a very large orchestra who does not write the score nor play a single instrument, yet has to understand and coordinate everything, and deliver a seamless whole.

In real life, the boundaries between conductor and orchestra can move and blur. Requirements, constraints and demands from the ultimate users, the designers, the contractors and workers on the ground, and the suppliers from many industries, all have to be accounted for and balanced. This is the complex and shifting terrain that Tapde deftly negotiated for many decades.

Also read: The Little Known Histories of Indian, British Engineers Before 1947

Tapde’s style and personality were key to his enormous contributions. He organised his own working space and time systematically, even amidst external chaos. His attention to detail, discipline, planning and tight scheduling were legendary. However, any preconception I may have had about him being a cold, dispassionate engineer was quickly dispelled when I shared a road journey with him or sat in a meeting with Tapde (both of which I did several times).

His quick purposeful movements, animated and usually smiling face, intense engagement in discussion, witty observations, occasional philosophical reflections and comments all yielded insights into the man behind the professional. People who knew Tapde for decades recall how there was so much more to Tapde as a human being than just the extremely competent engineer. This group included not just staff from IIA and NCRA, but also BARC, TCE and the Electronics Corporation of India. All have been touched by him, professionally and personally.

The visionaries like Vikram Sarabhai, Vainu Bappu and Govind Swarup who conceived of great projects are very well known in India. Suresh Chandra Tapde was the right man in the right places at the right times to catalyse the transformation of these visions into reality. The world should know more of him, and the largely unsung fraternity of those who deliver grand projects into the world.

Rajaram Nityananda spent more two and a half decades at the Raman Research Institute and one at the National Centre for Radio Astrophysics. He is currently with the Azim Premji University, and thanks his colleagues at NCRA for their help writing this article.

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