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ISRO’s Chandrayaan-1 – detected in lunar orbit

By Gurbir Dated: March 10, 2017 Leave a Comment

Using an innovative radar technique, NASA has been able to detect two spacecraft in lunar orbit from the surface of the Earth. NASA’s Lunar Reconnaissance Orbiter was launched in 2009 and was in lunar orbit at the same time as Chandrayaan-1. Although a joint experiment was designed for both spacecraft, it did not work out. LRO is still operating in Lunar Orbit today. Communication with India’s Chandrayaan-1 was lost in August 2009.  At the time ISRO engineers estimated that Chandrayaan-1’s orbit would decay and it would impact on the surface of the Moon by around 2012.  The new microwave radar technique using three of the world’s largest radio telescopes (Goldstone, Arecibo and Green Bank) first located the Chandrayaan-1 in July 2016. Remarkably it was still pretty much in its 200km polar orbit going round the Moon every 2 hours.

Chandrayaan-1 was originally (November 2008) in a 100km orbit which was raised to 200 km (May 2009)  to overcome internal heating problems. Although not welcomed at the time because the resolution of the data captured by several of the onboard instruments was reduced given the higher altitude. This raised orbit is probably the reason it survives in lunar orbit today.

One of the better write-ups, from 2009 about the demise of the Chandrayaan-1 mission from an accomplished Indian journalist T.S. Subramanian here.

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Book Review: ISRO’s Earth Observation Cameras

By Gurbir Dated: August 10, 2016 Leave a Comment

India’s Journey Towards Excellence In Building Earth Observation Cameras
India’s Journey Towards Excellence In Building Earth Observation Cameras

Title: India’s Journey Towards Excellence In Building Earth Observation Cameras

Publisher:  Notionpress.com

Author: Dr George Joseph

ISBN:  978-93-5206-998-9

As a late joiner to the space club, India’s space program was in “catch-up” mode for most of its early history.  Never the less, original technological innovation did take place. In this book, Dr George Joseph describes how the electro-optical sensors used on-board India’s Earth Observation satellites were designed, built and deployed. He knows because he was at the forefront leading this work during the 1970s and 1980s.

As with any account written by the those who are intimately involved, Dr Joseph brings a level intimate detail and authenticity that is not otherwise available.   His arrival at ISRO in 1973 was timely. He lead the team that built the imaging system (image intensifier and vidicon tube) for India’s first Earth Observation satellite, Bhaskara-1. In the 200 pages, the book traces ISRO’s deployments of new techniques and technology as the Indian Remote Sensing program (IRS) evolved during the 1980s. The quality and quantity of data captured increased as multispectral, stereoscopic, higher specification optics and digital technology was introduced.

ISRO’s history is littered with examples of imaginative solutions to overcome the deficit of resources.  Images of rocket nose cones transported on bikes or a bullock cart with rubber wheels for testing satellite antenna in a non-magnetic environment, have generated iconic images. They represent a lasting public perception of the ingenuity and frugality of the Indian space program. Dr Joseph describes another.  In 1973 when a dark room was not available, a kitchen in a residential apartment was converted in to one along with the solid work surface to an optical bench.

Most of the book is readable for anyone with an interest in this subject. Since,  Dr Joseph is a scientist, some technical terms such as “Modulation Transfer Function” and “scan mirror for off nadir viewing” are present. Although the book traces the evolution of imaging systems which was the author’s primary contribution during the early phase, it covers how those early techniques and technologies continue to support the 2008 Moon mission and the 2013 ISRO’s Mars Orbiter Mission.

Chapter 10 highlights another of ISRO’s contribution that many, even within India, do not appreciate – international collaboration. The US Landsat series of Earth Observation satellites was the premier supplier of Earth Observation data. During the 1980s, 1990s, and early 200s, problems with Landsat 5, 6 and 7 coincided with the time that ISRO’s EO constellation of  satellites matured. Despite the very different pedigree, ISRO EO data was sought by many nations to fill the gap left by Landsat. Chapter 10 looks at several examples of how data from ISRO’s satellites is used by Australia, Sweden, Italy USA, Brazil and Kuwait to help toward understanding and mitigating against the effects of climate change.

The book is fascinating resource not only detailing the evolution of a key asset of satellite imaging systems but the personal account of how that was achieved. An appendix with 5 sections at the end deals with some of the more technical and specialised areas such as Bhaskara TV Camera Failure Analysis, Supplementary Notes, Space based Electro-Optical Cameras of ISRO, Glossary and Memory Lane.  I found the Supplementary Notes and Memory Lane sections particularly interesting. They contain transcriptions of letters, notes and several B&W images of high quality capturing some of the key events from the time when the author was engaged with his ground breaking work.

This is an interesting read, even if you have no interest in ISRO per se. The description of space based imaging systems, by someone who built them, is sufficient justification for acquiring a copy.  How could the work be improved? This book has one of the better quality of post production that I have seen. Despite this however,  there are some minor typos that do not get in the way of comprehension but are a distraction. Something that copy editing or proofreading should have picked up. The other is my frequent complaint – absence of an index. The book is available on  paperback from Amazon but hardback only from the publisher in India www.notionpress.com. It is incomprehensible that in 2016, an ebook is not ALWAYS made available  at time of publication. A sample of the book, the forward, is available on the author’s personal website.

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Episode 72: Satish Dhawan Space Centre

By Gurbir Dated: June 1, 2015 Leave a Comment

ep72
From left to right. V. Seshagiri Rao Associate director, Dr M.Y.S. Prasad SDSC director, Dr S.V. Subba Rao Deputy Director

Located about 80km from Chennai on India’s east coast, Satish Dhawan Space centre is used by ISRO to launch all of its satellites including those to the Moon and Mars. Also known as Sriharikota, it was established during the late 1960s but today it has a vehicle assembly building, two launch pads and a state of the art mission control centre.

In this episode, Dr MYS Prasad, the director at Satish Dhawan Space Centre describes the key services and activities that take place at India’s 21st century rocket launch complex. This interview was recorded in January 2014 and Dr Prasad stood down as director on 31st May 2015.

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Episode 71: TATA Institute for Fundamental Research

By Gurbir Dated: May 25, 2015 Leave a Comment

 

Homi Bhabha 1909 - 1966
Homi Bhabha 1909 – 1966

The Indian Space Program was initiated by a brilliant nuclear physicist Homi Bhabha who pretty much immediately handed over the space program to Vikram Sarabhai. Bhabha himself pursued the goal of establishing premier scientific institutions for fundamental research in India. At the time he regarded scientific institutions to be critical for the new emerging independent India. Whilst working in the Indian Institute of Science, in 1945 he came up with the idea of an institution for fundamental research and went on to establish the Tata Institute for Fundamental Research (TIFR) which continues to operate today.

Opening ceremony  in 1954
Opening ceremony in 1954

Although separate organisations, the connection between ISRO and TIFR remains strong to this day. Many of the instruments and subsystem onboard ISRO’s satellites are designed and constructed within TIFR. In this episode, the former director of TIFR, Professor Mustansir Barma talks about Homi Bhabha, his achievements in physics and the role of the TIFR in modern India.

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