Milestone-Proposal:The Giant Metrewave Radio Telescope (GMRT) – Pune, India
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To the proposer’s knowledge, is this achievement subject to litigation? No
Is the achievement you are proposing more than 25 years old? Yes
Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes
Did the achievement provide a meaningful benefit for humanity? Yes
Was it of at least regional importance? Yes
Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes
Has an IEEE Organizational Unit agreed to arrange the dedication ceremony? Yes
Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes
Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes
Year or range of years in which the achievement occurred:
Title of the proposed milestone:
The Giant Metrewave Radio Telescope (GMRT), 1992
Plaque citation summarizing the achievement and its significance:
The Giant Metrewave Radio Telescope (GMRT) consisting of thirty antennas of 45m diameter, over 25 km near Pune , India, is one of the most sensitive low frequency (110–1460 MHz) radio telescopes in the world. The GMRT produced discoveries in a range of topics in astrophysics, which greatly enhanced our understanding of the Universe.
In what IEEE section(s) does it reside?
IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:
IEEE Organizational Unit(s) paying for milestone plaque(s):
IEEE Organizational Unit(s) arranging the dedication ceremony:
IEEE section(s) monitoring the plaque(s):
Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.
Street address(es) and GPS coordinates of the intended milestone plaque site(s):
GMRT Project, P. B. No. 6, Narayangoan, Tal – Junnar, 410 504, Dist – Pune, State - Maharashtra, INDIA , 19.096715, 74.049956
Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.
Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. The administrative block of the GMRT observatory.
Are the original buildings extant?
Details of the plaque mounting:
Proposed plaque to be placed on the wall in a prominent location in the Administrative Block of the GMRT observatory.
How is the site protected/secured, and in what ways is it accessible to the public?
It’s highly protected site, with limited access to outsiders; however, general public is allowed on specific dates and slots to visit the observatory.
Who is the present owner of the site(s)?
National Centre for Radio Astrophysics - NCRA-TIFR
What is the historical significance of the work (its technological, scientific, or social importance)?
Radio astronomy started at very low radio frequencies (~ 100 MHz) in the 1940s, but gradually moved to higher frequencies (~ 1000 MHz) by 1970s, due to a combination of reasons. However, there are a significant number of astrophysical problems that are best addressed at metre wavelengths. The radio astronomy group of TIFR, led by Prof. Govind Swarup, was one of the first to realise this, and proposed the GMRT in the late 1980s, and built it during the 1990s. The GMRT was thus one of the first in a series of new radio observatories that heralded the renaissance of low-frequency radio astronomy in the 1990s. Shortly after its commissioning, new facilities such as LOFAR, MWA, LWA were conceived and started becoming operational towards the end of the first decade of this century. On the technological front, the GMRT introduced several new ideas, and crossed some significant technological barriers. It was one of the first radio astronomy observatories to replace radio communication links with optical fibre technology to connect the antennas in the array to the central processing facility, a feature that is almost routine in all modern radio observatories. The design of the GMRT employed innovative ideas like SMART (Stretched Mesh Attached to Rope Trusses) to build very large fully steerable antennas (45 metres in diameter) that are very light (only 100 tons) and hence very economical, while still providing the required efficiency. The design of the electronics chain was also very challenging, especially the central digital signal processing system. Here, the GMRT was one of the first radio observatories to switch over to a software based implementation. The GMRT was also one of the first interferometric array telescope to also have a dedicated phased array mode to support observations of compact objects like pulsars. All of this resulted, in 2002, of the release to the global community, of the largest and most sensitive low frequency radio telescope in the world; a position that the GMRT has maintained over the years, supplementing it with a major technological upgrade carried out during 2012 to 2018 that keeps it on the forefront on the global scene. The GMRT has lived up admirably to its status as the most sensitive low frequency radio telescope, producing several new and interesting scientific results and discoveries in the 18 years or so of its operation. Each year, around 40-50 papers based on data from the GMRT are published in international journals. The range of science addressed by the GMRT is vast, covering many diverse topics :
- Solar & stellar studies: solar radio emission, radio stars, searching for extra-solar planets via radio emissions etc
- Galactic astronomy: including supernova remnants, micro-quasars, interstellar medium, the centre of our Galaxy etc
- Pulsars: searching, timing, emission properties, probing the interstellar medium
- Transient, explosive events in the Universe : Gamma-Ray Bursts, Fast Radio Bursts etc
- Extra-galactic astronomy : Galaxy evolution across cosmic time, gas and star formation, dark matter, radio galaxies and active galactic nuclei etc
- Galaxy clusters : Radio relics as probes of the intra-cluster medium, interactions between jets from active galactic nuclei and the intra-cluster medium etc
- Cosmology and the early Universe : studies of the Epoch of Reionisation, probing evolution of fundamental constants over cosmic time etc
- Major survey of the entire sky visible to the GMRT, to make the most sensitive atlas at 150 MHz, to date – the TIFR GMRT Sky Survey (TGSS).
In addition, the GMRT has also been used for interesting experiments in space science : for tracking critical space missions such as the landing on Mars by the Schiaparelli probe from the Exomars mission of the European Space Agency, in 2016.
On the social front, in addition to leading to a renaissance of low frequency radio astronomy in the world, the GMRT has also led to a major growth of professional astronomy in India, while also spurring the growth of a vast range of technology and capability growth in the country. A large number of students and scientists have been trained on the GMRT to become world class astronomers, and a strong engineering team has grown around the building, maintenance and upgrade of the facility. Today, the success story of the GMRT is widely and proudly recognised as one of the major accomplishments by the Indian scientific community of the country, on the global stage. Recently, in 2015, the GMRT was accorded the status of a pathfinder facility for the international Square Kilometre Array (SKA) project.
What obstacles (technical, political, geographic) needed to be overcome?
There were several technical challenges encountered (and overcome) in the GMRT project :
- The entire program was conceptualized, designed and fabricated indigenously; in the process several systems had to be designed and developed in house.
- The design of large but light weight antennas was a mechanical engineering challenge, which was successfully overcome with the innovative SMART (Stretched Mesh Attached to Rope Trusses) design.
- The in-situ fabrication of the large antennas to the required accuracy, when done on a shoe-string budget and by contractors who were not experts in erecting such large antennas, was also a challenge, and some ingenious but simple optimisation techniques allowed this to be done
- The design of the accurate drive train and servo system for the large antennas was another challenge; it was overcome by having a technical collaboration with the Bhabha Atomic Research Centre in Mumbai
- The first time use of optical fibre systems in a radio astronomy observatory posed its own set of issues – these were overcome by the engineering team with a “experiment, learn and grow” approach
- The design and fabrication of the complex digital receiver system was a difficult task and tool the longest to complete; the engineering team used a combination of collaboration and step by step scale up to achieve the final target
- Containing the systems generated radio frequency interference and mitigating that from external sources such as broadband impulsive and spectral line interference
The main political challenges encountered were :
- Providing sufficient compensation to the local population for the land acquired for the project, as well as for the fact that there is a zone around the GMRT in which there are constraints on the nature of industry and man made activities allowed
- Securing the funding : this was one of the largest and most expensive science projects proposed at its time in India, and it took a lot of convincing to have the funding approved
- Creating a radio frequency interference free zone, and a controlled industry zone around the observatory : there was a lot of resistance from the local population, and a lot of negotiations were required with various agencies
- Attracting sufficient talented manpower, given the somewhat remote location of the observatory
The main geographic challenges encountered were :
- Laying of optical fibre over long distances in populated areas, and maintaining it in the midst of ever growing human activity
- Identifying and procuring suitable land, including pockets for distant antennas
- Maintaining reasonable levels of radio quiet environment around the observatory : taking care of ever-increasing manmade Radio Frequency Interference (RFI) was and remains the biggest challenge till date
What features set this work apart from similar achievements?
The GMRT has a novel design, very well optimised to local conditions, and hence very different from other radio observatories around the world
- The GMRT was built at very low cost, compared to radio observatories of comparable size and capability around the world
- It has the largest collecting area at low radio frequencies, while having a very good resolution – this is a unique combination
- It has a very wide frequency coverage which has become much more complete with the recent upgrade – some of the frequency bands are not covered by any other facility in the world, at this level of sensitivity
- It has a phased array mode available concurrently with the interferometry mode, which make it a unique facility, and several novel science results have exploited this dual capability (which has now become the norm for new observatories)
- It has an interesting usage pattern : about 50% of the projects have PIs from abroad, and 50% from India – this leads to a balanced mix of the best innovative science projects from around the world, while allowing for healthy growth of astrophysics research within the country
Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.
The supporting texts are copyright, thus cannot be posted, but copies are on file at the IEEE History Center
Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to email@example.com. Please see the Milestone Program Guidelines for more information.
Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to firstname.lastname@example.org with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s).