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A brief history of 500 scientific balloon flights by the TIFR Balloon Group

Balloons, sometimes fondly called a “poor man’s satellite” with its promising high vertical resolution due to slow ascent rates, provide useful sub-orbital platform for measurement of various important scientific parameters that may not always be achievable from aircraft or satellite platforms.

The TIFR Balloon Facility, Hyderabad, offers a unique blend of expertise attained over decades of successful balloon experiments in the frontiers of Astronomy, Astrobiology, High Energy Physics and Atmospheric Sciences up to an altitude of 43 km. Ever since its inception, the TIFR Balloon Facility has been relentlessly carrying out Research & Development efforts in improving the design and development of plastic balloons, control instrumentation and launch facilities comparable to those at other leading scientific ballooning centers in the world. The TIFR Balloon Facility provides complete solutions in scientific ballooning right from balloon design, fabrication, payload integration, control instrumentation and tracking support, balloon launch and payload recovery, all under one roof. It is one of the leading balloon launch facilities in the world. In addition, the TIFR Balloon Facility also regularly conducts public outreach programs, comprising brief talks on various activities of the balloon facility, exhibition of balloon flight equipment and accessories, demonstration of balloon launches,to motivate and inculcate the spirit of space science among students from various universities and colleges in India.

The art and science of scientific ballooning in India has evolved over the years with the scientists’ requirements as the primary focal point. Balloon flights for cosmic ray research were initiated in India by Dr. Homi Jehangir Bhabha at TIFR in the year 1948. During 1948-58, clusters of rubber weather balloons were deployed to carry modest weight cosmic ray instruments to altitudes of about 30 km (fig.1). These flights were conducted from several locations in India, such as Bombay (Mumbai), Madras (Chennai), Bangalore (Bengaluru), Delhi and Srinagar, covering a range of geomagnetic latitudes. This cluster of rubber balloons had limitations in terms of load carrying capability, reaching higher and predetermined altitudes and maintaining long float durations, while all these aspects were becoming increasingly important for primary cosmic ray experiments. It was, therefore, decided to develop a new technique of flying large zero pressure plastic balloons capable of carrying heavier payloads to higher altitudes and with this in view, a plastic balloon design and fabrication project was started in TIFR during the year 1956. When the TIFR group started balloon fabrication work in 1956, only limited information was available and the group, more or less, developed the plastic balloon techniques independently.

Fig.1: (Left): Mr. Vasudevachari inflating a rubber balloon along with Dr.Homi Jehangir Bhabha (1948), (Middle): Cluster of 50-60 rubber weather balloons carrying a cosmic ray instrument (1948), (Right): Dr. Homi Jehangir Bhabha with a cosmic ray payload at Osmania University, Hyderabad (1959).

When the balloon work started in TIFR in 1956, initial trial balloons were made using commercially available polyethylene film (Black film, painted film and Visqueen sheets). These balloons could not survive passage through the equatorial tropopause region with temperatures in the range of -78 deg C. The first plastic balloon flight conducted from the Old Tata Oil Mills, Sewri, Bombay (Mumbai) during April 1957, carried a cosmic ray photo emulsion payload. To overcome the problem of balloon bursts at the tropopause region, the TIFR balloon group hit upon an ingenious method of making balloons out of black tinted polyethylene film. The balloons made out of such a film would survive the passage through tropopause; as the balloon film absorbed solar radiation and the consequent heating would keep its temperature well above the cold brittle point of the balloon film. These balloons were known as ‘black balloons’. All these balloon flights were carried out during the day time. After twenty three trial flights in December 1958, the first successful flight with black painted polyethylene film balloon was carried out from the Old Tata Oil mills, Sewri grounds in Bombay (fig. 2). For a decade since 1959, plastic balloon flight programs were carried out annually from the campus grounds of the Osmania University, Hyderabad. The ‘black balloon’, however, could be used only for day launches. Therefore, for night launches, being an important requirement of Astronomy experiments, a ‘white balloon’ or ‘transparent balloon’ technique was developed. With the increased demand for more balloon flights, bigger balloons and heavier payloads, a need for improved technical / engineering and logistics support and launching facilities was felt. Hence, TIFR established a permanent integrated scientific balloon facility in the year 1969 at Moula-Ali on the out skirts of Hyderabad. Since late 1969, regular balloon flights with sophisticated advanced instruments are being conducted from the TIFR Balloon Facility, Hyderabad (fig. 3). These balloon flights have resulted in important scientific results in different areas of space science. The facility has been extensively used in the past 45 years by scientists from the National and International Laboratories and Universities including USA, Russia, the UK, Japan, Germany, Spain, Canada, Singapore and Italy.

Fig. 2: Prof. M. G. K. Menon and Prof. G. S. Gokhale during inflation of ‘black balloon’ at the Old Tata Oil Mills, Sewri, Bombay (1958).

Fig.3: Balloon launch from TIFR Balloon Facility launching ground, Hyderabad (1969).

TIFR Balloon Facility, Hyderabad today has the capability to launch heavy payloads of up to 1200 kg gross weight to altitudes of 32 km for Astronomy experiments and medium payloads of up to 600 kg to 42 km for High Energy Physics and Atmospheric Science experiments. In recent years, thin film balloons carrying 10 kg lighter payloads have reached record altitudes of 51.8 km and small zero pressure plastic balloons carrying light Atmospheric Science payloads have floated for several hours for collecting aerosols and water vapour particles in the coldest tropopause region between 15 to 18 km altitudes.

The TIFR Balloon Facility achieved the landmark of 500 scientific balloon launches on 13 April 2018 (fig. 4). In this balloon-borne experiment (T500), a specially designed and fabricated zero pressure balloon of volume 3,026 cu.m made out of 15 microns Antrix film was used. The balloon was launched from Hyderabad with a D-15 payload weight of 57.5 kg up to an altitude of about 25 km above mean sea level (amsl). The payload consisted of instrumentation packages and other developmental instruments. After successful completion of the mission objectives, the balloon flight was terminated and the payload was safely recovered 102 km south-west of the TIFR Balloon Facility, Hyderabad.

fig.4: Hydrogen inflated T500 balloon is ready for take-off on 13th April 2018.

On the occasion of 500 scientific balloon flight, we remember the pioneers of scientific ballooning in India: Dr. Homi Jehangir Bhabha, Prof. M. G. K. Menon, Prof. G. S. Gokhale, Prof. A. S. Rao, Prof. R. R. Daniel, Prof. B. V. Sreekantan, Prof. S. V. Damle and Mr. R. T. Redkar, whose great struggles and innovations were instrumental in learning new techniques and developments to meet the present and future scientific ballooning requirements.

Prof. Devendra K. Ojha,
TIFR Balloon Facility Committee.