Raghubabu Ponakala, 1966–2026
Scientist-Engineer SG, LEOS • UR Rao Satellite Centre • ISRO, Bengaluru
It was past ten o’clock on a Tuesday night in the cavernous integration hall of ISRO’s Laboratory for Electro-Optics Systems, Peenya, Bengaluru. The rest of the floor had emptied — the day-shift engineers gone, the fluorescents powered down to a single row above the sensor test bench. But one terminal was still lit, and one man sat before it, unmoving, reading numbers.
On the screen before him was the calibration trace for Earth Sensor Unit No. 47, destined for a GSAT communication satellite that would be launched within the year into geostationary orbit 35,786 kilometres above the equator. The sensor’s job was absolute: detect the precise thermal boundary between the warm disc of Earth and the cold void of space, translate that boundary into a nadir vector, and feed that vector to the spacecraft’s attitude control system so the satellite would always know which way was home. One degree of error in this sensor’s reading meant antennas drifting off-target, solar panels tilting from the Sun, and a communication backbone serving millions of Indians slowly going dark.
Unit No. 47 had a problem. It was a small thing — a seventeen-millivolt asymmetry in the detector bridge output at the second scan crossing — the kind of deviation that most engineers would have dismissed as thermal noise or flagged for next morning’s review. The man at the terminal had seen it three times in the last four hours in three different temperature profiles. He was not dismissing it. He was not deferring it.
He knew each transistor in that bridge by its part number and its individual thermal coefficient. He had characterised the pyroelectric detector stack himself during incoming inspection. He knew, without needing to run the fault-tree, that this asymmetry was a micro-crack in the detector’s substrate mounting — invisible to the eye, undetectable in room-temperature testing, but catastrophic in the thermal cycling of geostationary orbit where temperatures swing 250 degrees between sunlit and eclipse.
He pulled the unit from the test jig himself, tagged it for rejection, raised the anomaly report, and began writing a corrective action note for the assembly team. He would not leave until it was written. The satellite could not afford a blind eye in space. And Raghubabu Ponakala could not afford to let one go.
That scene — the empty hall, the single lit terminal, the one man who caught what others would have missed — did not happen once. It happened, in various configurations, across nearly four decades, producing more than sixty Earth Sensor units that flew aboard India’s INSAT and GSAT fleets and continue to orbit, this very moment, watching the curve of the Earth with the precision he spent his life instilling in them.
FROM A VILLAGE BENEATH ANDHRA’S SKIES
The man who would one day design the instruments that told India’s satellites where they were in the universe was born in Naguluppadadu, a small village in the Prakasam district of Andhra Pradesh. He grew up in the unhurried rhythms of rural life, where the sky above was wide and unobstructed and academic achievement was the most credible ladder available to a young mind of ambition.
In 1984, he arrived at VR Siddhartha Engineering College, Vijayawada — a first-generation engineering student, carrying with him the simplicity of his upbringing and, concealed beneath it, an intellect of uncommon range. The college was his first real encounter with peers drawn from across Andhra Pradesh, and the encounter was revealing — revealing above all to those peers. The village boy who dressed without fuss and spoke without flourish was, within weeks, the person the rest of the class turned to when equations refused to yield.
His batchmates from the 1984–88 cohort, many of whom have tracked his career closely over the four decades since, reach for the word “prodigy” when they try to describe him — and then immediately qualify it. It was not the narrow prodigiousness of a single discipline. It was a systemic fluency: mathematics, electronics, circuit theory, systems thinking. He saw structures inside problems that others saw only as problems. And he explained them, when he bothered to explain at all, with a clarity that made his classmates feel briefly brilliant for having understood.
What his classmates remember with equal warmth, however, is not the intellect but the man carrying it. He had, as one batchmate and also his roommate Ravi Kamaraju K put it, “zero interest in the business of being impressive.” The frugality was genuine, the simplicity was unperformed, the absence of ego was constitutional rather than cultivated. In a college environment where academic competition could harden into rivalry, Raghubabu generated neither envy nor resentment. He was, his friends recall, impossible to dislike.
THE SCANNING EARTH SENSOR MAN
After graduating in 1988, Raghubabu joined the Indian Space Research Organisation and was posted to the Laboratory for Electro-Optics Systems (LEOS) at Peenya, Bengaluru — ISRO’s dedicated centre for the design, development and production of electro-optic attitude sensors for all of India’s spacecraft programmes, from Low Earth Orbit missions to deep-space probes. Within the wide portfolio of sensors LEOS handled — Earth sensors, Sun sensors, star sensors, magnetometers, fibre-optic gyros — Raghubabu found his life’s domain with the instinctive certainty of a person who recognises home.
The Scanning Earth Sensor. An infrared horizon sensor. A device that scans the thermal boundary of the Earth’s limb and, from the geometry of that scan, derives the nadir direction of the satellite — the vector pointing back to the centre of the Earth. In geostationary orbit, where India’s communication satellites must hold their position with extreme accuracy to keep antennas locked on their ground footprints, this sensor is not optional instrumentation. It is the satellite’s fundamental orientation reference. Without it, attitude control collapses. The satellite tumbles. The mission ends.
He understood this before most of his colleagues had fully appreciated it. And he devoted himself to it with a singularity of focus that, over the years, transformed him from a junior engineer learning the sensor into the person LEOS came to when the sensor had a problem. Colleagues, like VVR Reddy, recall that he knew “each and every component” of the Earth Sensor hardware — not as a theoretical matter but as a living, tactile knowledge: the thermal coefficients, the detector characteristics, the interface quirks, the ways the sensor behaved differently in vacuum than on the bench. When anomalies surfaced during spacecraft-level integration, or during the tense hours of post-launch attitude acquisition at the Master Control Facility, Raghubabu was the man they called.
Over the arc of his career, he delivered more than sixty Scanning Earth Sensor units for ISRO’s INSAT and GSAT communication satellites — the backbone of India’s domestic telecommunications, broadcasting, disaster management and meteorological infrastructure. He tested each unit at spacecraft level. He supported each satellite’s initial orbit-raising and attitude-acquisition phase from the MCF. He was, in every meaningful sense, responsible for the sensor from the moment it entered his lab to the moment it began its operational life in orbit. LEOS’s own records acknowledge that over a hundred scanning Earth sensors have flown on ISRO communication spacecraft. Raghubabu’s hands are on more than half of them.
SOFTWARE, PRODUCTION AND NEW FRONTIERS
The depth of his expertise compelled him to extend it. He wrote the first two-axis Huber controller software for Earth Sensor testing — a control algorithm that became the foundational engine for automated test consoles for both Earth Sensors and Sun Sensors at LEOS. The contribution was quietly transformative: by codifying his sensor-level knowledge into repeatable software infrastructure, he moved LEOS from engineer-dependent manual testing towards a standardised, mission-consistent production capability that would outlast any individual’s presence.
As ISRO progressively opened its supply chain to Indian industry, Raghubabu trained vendor engineers personally — transferring three decades of flight-proven manufacturing knowledge to external organisations without diluting the quality standards that had made LEOS sensors reliable. He streamlined the initial production activities for LEOS’s first star sensor production line, extending his organisational reach into the higher-precision attitude sensors that complement the Earth sensor chain. And in the laboratory’s forward technology agenda, he laid the initial conceptual foundations for an Optical Communication Terminal at LEOS — seeding a capability that has since become a declared next-generation thrust for the organisation.
His career trajectory carried him, in due course, into leadership: first as Head for Sun Sensors, Earth Sensors, and Magnetometers, and later as General Manager overseeing all Sensor Assembly and Fabrication activities at LEOS. His formal seniority was confirmed in URSC’s official records as Scientist/Engineer-SG at Level 13A, among the highest technical grades in ISRO’s hierarchy. He held that seniority with the same indifference to its outward significance that had characterised everything else about him.
‘ZERO HATERS IN THE OFFICE’
Ms. Yandrapalli Vijaya, Group Director of LEOS at URSC, who worked with Raghubabu over many years, paid tribute in terms that capture both the professional and the personal:
“From the time he joined, he dedicated himself entirely to the Earth Sensor. He is totally responsible for delivering more than 60 Earth Sensor units for all INSAT and GSAT missions. He was equally responsible for testing Earth Sensors at spacecraft level and during post-launch operations at MCF. He was so thorough with all circuits — he knew each and every component. He wrote the first two-axis Huber controller software, which became the basis for automated test consoles for Earth Sensors and Sun Sensors. He laid the initial foundation to develop an Optical Communication Terminal at LEOS. He trained external industry people to deliver Scanning Earth Sensors. He streamlined the first Star Sensor production activities. He worked as Head for Sun, Earth and Magnetometers, and later held the GM post for all Sensor Assembly and Fabrication activities. He is the person we can see in purest form. He has zero haters in office. Very innocent and straightforward. The way he speaks — and his voice — is so lovely.”
Ms. Yandrapalli Vijaya, Group Director, LEOS, URSC, Bengaluru
A QUIET BATTLE, A SUDDEN END
He had been fighting colon cancer, and — in the manner entirely characteristic of him — fighting it quietly. Surgery was done. Recovery had begun. Friends and colleagues, who had learned of his condition through the subdued channels of alumnus networks rather than from the man himself, had begun to allow themselves cautious relief.
On 12 May 2026, a sudden and severe brain stroke — silent until its final strike — claimed Raghubabu Ponakala at M.S. Ramaiah Hospital, Bengaluru. He was sixty. He did not suffer. He simply stopped, as quietly as he had always lived.
He leaves behind his family, his colleagues, the alumni circle from VRSEC Vijayawada who had tracked his quiet journey for forty years, and more than sixty attitude sensors in geostationary orbit that continue, at this moment, to do exactly what he spent his life teaching them to do.
The universe does not record the names of those who calibrated the instruments that measured it. But the instruments remember. And those who know what a Scanning Earth Sensor does — what it takes to make one perfectly, to deliver sixty of them without a single on-orbit failure, to give a satellite its bearings in the cold indifference of space — those people will understand what was lost on the afternoon of 12 May 2026 in a hospital room in Bengaluru.
