Note: I wrote this on my earlier blog hosted as http://parallelspirals.blogspot.com. I recovered the text from the WayBack Machine. This post appeared on February 7, 2011 as per the time stamp. I’m trying to collect here again all my old writings spread on various blogs.
Today’s Chai and Why session at Prithvi Theatre, Juhu was on “Scientific Ballooning”. Manchanda, who has been working with TIFR for about 44 years was faced with a young school going audience brought there in two buses. Manchanda presented about scientific ballooning work done at the National Balloon Facility, Hyderabad and also shared some of the interesting applications and research from the field of scientific ballooning.
Delving into history, Manchanda said that the first balloon was flown on June 4, 1783 and was a paper balloon flown using smoke. The first scientific application of balloon was made in 1912 to study the source of radiation. He shared pictures of early flights of these balloons from India, some even done by Indian scientists like Homi Bhaba. He shared that some of the first balloon was fabricated in the basement of the TIFR, Colaba campus before the current National Balloon Facility was setup in Hyderabad. He ended by mentioning the example of Lighter than Air (LTA) balloons.
After a brief description of Archimedes Principle, the working principle of the balloons. He said that the research balloons had a thin film of polyethylene and were filled with lighter than air gases like hydrogen and helium. On the point of why we used such research balloons, Manchanda said that these were to bypass the effect of the atmosphere which absorbed certain wavelengths of light. He said that it was mainly used for the study of the Very Cold Universe or InfraRed Astronomy and the Very Hot Universe in the ultraviolet and gamma astronomy. He said some of the science themes that balloons cover are astroscience, Earth Sciences and heliophysics. A new and rising field is called Geo Engineering and the balloons are working towards contributing in the field.
Manchanda believes that balloons had a few advantages. He said that balloons could be launched from anywhere, could be made ready in around 6 months, was low cost and was a very stable platform for long duration flights.
Getting back to the National Balloon Facility he said it was established in 1971. It is one of the 5 such establishments in the world and the only one that fabricates its balloons. He said that besides the science, it was also a technology center and hence also conducted research on ballooning to meet the requirements of future science applications. It was started by a gentleman by the name of Gokhale in 1971 who took over the efforts in Hyderabad. Some of the lab facilities like a 184 meter long table, labs for Quality Control, Telemetry and Data Centers and boasts of a 100% flight success rate (with success even during testing phases). In the QnA session, Manchanda said that the Quality crew worked as the balloon was sewed together. These are hand sewn balloons with about 185 sections. The Facility has carried X-Ray, LIDAR, Gamma Ray and InfraRed payloads. The facility has been used by other countries as well and has even been sent out to countries like the US and Canada. He said that the lab had achieved 100% indigenous development capability.
Talking about the balloon flight, he said it went through various stages like planning, wind sounding, launch operations, tracking and cut off and recovery of payload with parachute. Going in depth, he said wind sounding was done to enable to understand the possible track and inform air traffic controllers. He later showed a video explaining the launch operations (unfurling of the balloon, attaching of the payload, filling the balloon with hydrogen gas, tensioning the payload tether and launch of payload). It was tracked using Google Earth using GPS and other modes. When it was ensured that it was in an empty space, cut off instructions were given. The payload would separate from the balloon, a rope attached to the skin of balloon would tear and empty the balloon and would fall on land with a parachute system.
Talking about applications of the balloon systems since 2001. Called the diversity plan, the Centre has concentrated on tethered vehicle, remote operations, airships and balloons. The work on tethered flight was on science, surveillance, disaster management etc. TIFR has been working with Tata Indicom to fly a tethered balloon to a height of 500 meters which helped provide a cell phone network of 60 km region. Normally, the network infrastructure is deployed on top of a building which provides a 3 km region and could pose as a health hazard. Currently, this balloon is planned for rural operations where deploying a cell network would be very expensive.
Another application is something called a quasi geosynchronous platform. Manchanda said that at altitudes of 18-20 km, there was a region where wind velocities fell to almost zero. Deploying balloon platforms to this height would provide an opportunity for providing communication systems.
Talking about ballooning, Manchanda said they were considering balloon flights from Andamans to mainland India (Chennai) and flights over the South pole from India’s Antarctic Station, Maitri. The flight from Andamans to Chennai would give a flight time of 3 days and covering a distance of 4500 km, which provides a lot of time for conducting experiments. From Maitri, Manchanda said, the circular pattern of winds over the South pole, would allow balloons to fly in circles, remain in eye contact and could travel for upto 3 weeks, extending the time provided for collecting science data.
Answering a question of why Hyderabad was chosen as the site of the balloon facility, Manchanda said that the closeness to Equator provided improvement in sensitivity of instrument measurements due to rigidity of the magnetic fields near the Equator for studying certain kinds of particles.
Answering another question, Manchanda said that the largest balloon would cost about Rs. 50 lakhs while the smallest balloon would cost about Rs. 50,000.
He mentioned that general operation balloons had a thickness of 6 microns while the ones launched before rocket launches from Sriharikota would have films as thin as 3 microns. He said that each hand sewn balloon had to be filled with 1 cubic meter of Hydrogen to lift a kilogram of payload. Balloons were generally only filled upto 40% to allow for their expansion when in rarer atmosphere at high altitudes. He also answered that various factors led to the balloon launch being either in the night or early morning.
R K Manchanda is also working on a payload for ASTROSAT and said that student payloads are accommodated for free as piggyback. He can be reached via email at ravi@tifr.res.in.
Parallel Spirals 