Tapan Misra
Congratulations to Team ISRO and JPL-NASA for successful launch of NISAR (NASA – ISRO SAR – Synthetic Aperture Radar) today, 30 th July. A great finale to a collaborative project, spread apart in two continents, two different working cultures. However, NISAR is the project with one of the longest gestation period in ISRO’s experience, almost 14+ years. This delay was less to do with technology issues and apt for management case study.
JPL team visited SAC in December 2011 with a proposal for L band sweep SAR. We prepared in three days a SAR configuration to suit the best to most of the applications envisaged. The configuration stood the test of the time.
In next joint meeting in ISAC (present day URSC) on 24th January 2012, from ISRO side I proposed S band contribution. The idea came from L-S band SAR we already built for Chandrayaan 2 orbiter. The rationale was: observation in two frequencies will have different foliage and ground penetration, leading to better estimate of biomass and better interpretation of differential interferometry.
It was a harrowing day. RISAT was being installed in the 9 metre thermovac chamber. On the same day, so called Antrix Devas imbroglio burst forth on TV screens. I was running in and out of the meeting to supervise initiation of thermovac testing of RISAT, taking occasional glances on TV screen for unfolding Antrix Devas drama and convincing JPL team, who were slightly less inclined for this addition.
We launched RISAT on 26th May, 2012. In July same year, I visited US State Department in Washington as part of Indo-US Strategic Dialogue. During Samosa Break, then NASA Chief Dr. Charles Bolden took me aside and whispered, “Did you build RISAT at such a cheap cost of so and so million Dollars?”. I answered diplomatically, “Sir, your guess is quite close.” He promised to visit RISAT lab to understand how ISRO builds sophisticated space hardware so cheap. Dr. Charles Bolden did visit SAC in August 2012, strolled around RISAT clean room, had a look at the facilities and technologies being developed. That day he was convinced on the win-win nature of joint collaboration in NISAR project.
NISAR was originally named as INSAR. In order not to confuse with the abbreviation of Interferometric SAR, the name was changed to NISAR. I had to agree reluctantly.
In 2016-2017 time frame, there was an after thought from senior leaders, put forward to me as lead role as well as Director, SAC to drop the S band SAR from NISAR. I played rope-a-dope to new found brain wave coming from influential higher ups. Today I feel vindicated that this right stand did stand the test of the time and made ISRO an equal partner rather than a junior one.
In between I could figure out that if the NISAR foot print was yawed by 90 degrees, we could actually have a MIMO strip map SAR with spotlight-mode like high resolution. This idea resulted into an ISRO patent. An improved configuration and algorithm won an IDEX award for our Startup Sisir Radar. Sisir Radar made further innovation to achieve world’s first sub- wavelength azimuth resolution with our Drone borne Dual Frequency L-P band SAR. We have nomenclatured this innovation as Complex Multi Look SAR.
Tapan Misra, founder of SISIR Radar, is a distinguished space scientist. Known in knowledgeable circles as father of Indian Synthetic Aperture Radar (SAR), he is former Director Space Applications Centre.
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