Unfortunately, ISRO frittered away the advantage of the technology leadership of RISAT. It is a classic example how leadership failed ISRO in seizing technology leadership Tapan Misra, Distinguished Scientist
Newsroom24x7 has been following closely the happenings and exposing the irregularities and a series of failures, all linked to leadership deficit in Indian Space Research Organisation (ISRO) over last many years.
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Today we are not drawing the curtain on the affairs of India’s premier agency entrusted with the responsibility of carrying forward the country’s space programme but lifting the curtain by reproducing from social media this post by distinguished scientist Tapan Misra, who has contributed immensely to ISRO.
You can never resist an idea whose time has come
In the midst of all pervading panic and gloom due to the second surge in Covid-19 pandemic, I was pleasantly surprised to receive a compliment from Russel Keith Raney for my quite forgotten contribution in SAR technology. I was complimented by Professor Keith Raney for my ‘vision and leadership’ in bringing to fruition Hybrid Polarimetry, firmly in the lexicon of SAR technology and architecture, in the following e-mail:
Russell K Raney Fri, Apr 23, 3:57 AM
After many months of wrangling with paper submissions and negative reviews by “specialists” who seem to regard hybrid polarimetry as a death threat, we have successfully published a relevant and hopefully a valuable paper on the subject. If you are still interested in such things, I suggest you look over
RADARSAT Constellation Mission’s Operational Polarimetric Modes: A User-Driven Radar Architecture
Thank you for your vision and leadership on this theme!
To the SAR community, Dr. Keith Raney needs no introduction. For a wider audience, his contributions led to some very significant milestones in the evolution of SAR technology. During the launch and operation of pathbreaking SEASAT SAR in 1978, JPL and NASA were firmly convinced that there cannot be a better SAR processor than the complex optical SAR processor, developed by JPL. He differed and left for Canada, leading the development of digital SAR-processor which brought unimaginable flexibility and simplicity in the design of various SAR modes and their imaging.
Because of his contribution, Canada was elevated in the firmament of leading SAR technology power. He inspired the RADARSAT programme, designed architecture of the famed Mini-SAR from NASA, on-board Chandrayaan-1. His patented Chirp scaling algorithm that brought out major quality improvements in SAR imaging.
I recollect a presentation of a two-page paper by Dr. Raney in the EUSAR 2006 conference in Dresden. He talked about introduction of Hybrid Polarimetry in SAR imaging, where circular polarisation signal will be transmitted and return signal will be received in two orthogonal linear polarisations. The idea, derived as an extension of conventional astronomy measurements, was lukewarmly received by expert scientists, wedded to conventional Linear Polarimetry. In this mode, alternately signal is transmitted in two orthogonal polarisations; but in each case, the return signal is received in two polarisations.
I had a short discussion with him, over a cup of black coffee, during coffee break, following the session. I could grasp that the presented idea, beyond the dry mathematical formulations, is revolutionary as the data rate will be reduced by half. We concluded after detailed discussion that it will meet most polarimetric applications, probably leaving a few esoteric ones. Conventional linear polarimetry mode is designed as a special mode, operated at lower incidence angles only, in strip map mode of operation. Whereas, the suggested hybrid polarimetry can be operated in any of the SAR modes like scanSAR, spotlight, TOPSAR etc. and obviously in conventional strip map mode. Added to this advantage, there will be no limitation in incidence angle. To put it succinctly: the idea was leading to democratisation of polarimetry.
On the con side, new algorithms for decomposition are to be invented to work with Stoke’s parameters. Present algorithms of decompositions need to be tailored to Stoke’s parameters. All the industry-developed software on linear polarimetry has to be given ‘bye bye’ to usher in new polarimetry.
There was another issue, all SAR systems, other than RISAT, which we were pursuing, will not be able to implement this polarimetry as they use one transmitter, shared by two polarisations through a switch. Whereas RISAT had dedicated exclusive transmitters in each polarisation. We designed RISAT as two SARs, operating independently in two polarisations. In case of major power failure, we can ensure operation in single polarisation. I could figure out that RISAT can take advantage of its unique architecture, to become a harbinger of opening a new era of SAR imaging. All can be achieved by simple software changes in the top level of payload control software.
On my return, I put forward the idea to our scientists and our Director. I was stunned by the severity of the opposition. I was even humiliated in a meeting to discuss the proposal. One Deputy Director, even gave me a suggestion to abandon the idea, if I want to save my future career. I went ahead and implemented hybrid polarimetry as an optional feature to all the imaging modes. But the opposition continued unabated. After the launch, another top man of SAC, virtually outlawed operation of hybrid polarimetry with its ostensible crime of being novel and its operation was relegated to occasional out of India coverage. Needless to say, ISRO and India lost an opportunity to become a world leader in SAR technology and application.
In retrospect, I try to analyse the reasons for visceral opposition to the excellent feature of RISAT, from ISRO itself, specially from SAC and NRSC. They are:
- Technology innovation was probably ahead of its time
- Our lack of confidence in implementing a technology which has not been implemented in western world. We suffer from psychological satisfaction in being “also ran” than being front runners.
- Organisation immune system rejection, manifesting as allergy symptoms
- Our scientists were enjoying a comfort zone of running imported software and to pass it on as research. When they were faced with the prospect of developing new algorithms for hybrid polarimetry, they were on the verge of being caught that they already ceased to become relevant in terms of scientific innovation. So, they collectively employed the doctrine of “offence is the best defence” and management also chickened out in front of formidable scientific groups, masquerading as experts. They are no exception and can be noticed in almost all Indian institutions.
- Internationally there were vested interests of conforming to linear polarimetry as massive commercial interests were riding on many commercial software, developed over decades. Suddenly they came face to face with the spectres of going into oblivion and competing with new players.
- A clandestine campaign was probably being carried out by international commercial SAR operators, both civilian and military, who were finding RISAT as a formidable competitor because of this hybrid polarimetry capability. Internal opposition was thus fanned to limit the RISAT to conventional operations.
- RISAT was capable of operating for the first time in spotlight mode with polarimetric capability, giving it an impressive edge over all existing military SAR operators in classifying man-made targets.
I was invited for a workshop to define RCM (Radarsat Continuity Mission) in Canada in Montreal in 2013. I shared my experiences of RISAT, launched in the previous year. I experienced severe opposition to the idea of Hybrid Polarimetry from an army of experts in Linear Polarimetry. I was even accused of misleading the global SAR community. As the email from Dr. Keith Rane indicates, the opposition is continuing still after one and half decades.
On the flipside, RCM has adopted Hybrid Polarimetry as a major operational feature. All new SARs are getting equipped with this feature. It appears that the chickens have come home to roost for all the opposing scientific and commercial forces. It is difficult to resist an idea of remarkable innovation whose time has come. Though I paid the price by daring to innovate against the wishes of powerful people at the helm of affairs, I have the personal satisfaction that RISAT was the first payload from ISRO which set many new standards, apart from Hybrid Polarimetry. Another new standard was the first spotlight imaging in sliding spotlight mode, that too in C-band.