The Indian Space Programme

by Gurbir Singh

Initial design

  Designated GEO location at 102°E

  Operational life of 2 years

  Ni-Cd battery of 240 watts and two solar arrays.

  Total mass

  672 kg (380 kg propellant)

  Dimensions

  1.2 m diameter and height

  Launch date

  19 June 1981. GTO 201 km by 36,206 km

  Transmitter

  2 C-band transponders

  Designated operational

  13 Aug 1981. Final GEO orbit of 35,500 km to 35,900 km

  Mission terminated

  19 September 1983

  Table 12‑3 Overview of Ariane Passenger Pay Load Sequence of Events

  During the late 1970s, Indian industry did not have the capacity to build all the space-qualified components and systems ISRO required. To generate electricity, Aryabhata had used body-mounted solar cells. Since the surface area was small and only a part of it could be facing the Sun at any one time, the power it could generate was limited. Additional services of a communication satellite required increased power. GEO satellites are further from Earth, and the nature of communication services makes greater demands on power. Body-mounted solar cells would not suffice, and solar panels that could continually face the Sun would be needed for APPLE.

  The lack of some facilities generated some inventive and anachronistic innovations. In the absence of electromagnetic testing facilities, a bullock cart with rubber tyres provided a “non-magnetic environment to conduct the antenna test in an open field to remedy the TT&C link problem caused by the impedance-matching problem. The solution was found quickly at the cost of Rs. 150 ($19) for hiring the cart.”[689]

  India did not have the capability to fabricate space-qualified solar panels or rechargeable batteries. Consequently, the solar panels for APPLE were acquired from Spectrolab, a US company, and the 240-watt Ni-Cd battery was supplied by Saft of France. APPLE used momentum wheels and RCS for attitude control. One of the momentum wheels was manufactured at VSSC, and the other came from Teldex in what was then West Germany.[690]

  Figure 12‑4 APPLE Electromagnetic testing on Bullock Cart 1981. Credit ISRO

  The Hamilton Standard RCS used for attitude control came from the US. ISRO had developed a unique passive thermal control system using paints, multi-layered insulation blankets, optical solar reflectors and specially treated surfaces for Aryabhata and used that design approach once more in APPLE.[691] In its final form, the 672-kg APPLE was a three-axis stabilised cylinder with a diameter and height of 1.2 m, topped by a 0.9 m parabolic antenna for the two C-band transponders and two solar panels for recharging a 240-watt battery. It was designed for a lifetime of two years.

  ISRO developed APPLE using the three (Structural, Engineering and Flight) model philosophy. ESA had insisted that a structural model of APPLE be kept in France. Should ISRO not be able to produce the flight model of APPLE, ESA would then proceed with the structural model instead to allow ESA to test its satellite-deploying mechanism. Had the structural model been flown, ISRO would have suffered “considerable humiliation.”[692] APPLE was completed in time and tested in India by the joint effort of several ISRO teams.

  APPLE was flown out of Bangalore 45 days prior to launch accompanied by a team of ISRO engineers.[693] While the solid-fuel apogee motor was transported to France by aircraft, the liquid-hydrazine fuel made in Thumba for the reaction control engines was transported to Guiana by ship in specially constructed containers. Ariane’s launch capacity allowed ESA to launch more than one satellite at the same time. APPLE was launched with two other spacecraft both from ESA, an engineering test vehicle called Capsule Ariane Technologique (CAT-3) and a weather satellite METEOSAT-2[694]. In the launch configuration, APPLE was positioned in the middle with the primary payload METEOSAT-2 above and CAT-3 below in the Ariane payload bay. The first four flights had been designated experimental by ESA. The first flight of Ariane 1 in December 1979 had been a success, but the second flight in May 1980 had failed. APPLE was launched on Ariane’s third experimental flight from ESA’s Guiana Space Centre in South America on 19 June 1981. Sixteen minutes after launch, the Ariane launcher first released METEOSAT-2 followed by APPLE.

  Ariane put APPLE in a GTO of 201 km by 36,206 km with an orbit of 10 hours and 40 minutes. From this highly elliptical orbit, it was up to APPLE’s own rocket (known as an apogee motor) under ISRO engineers’ command to move the satellite from GTO to GEO to its designated longitude of 102°E and a circular orbit at 35,900 km above the Earth’s equator with a period of 24 hours. The onboard engine used by APPLE for this manoeuvre was a modified fourth stage of ISRO’s SLV-3 launcher. The apogee motor with 314 kg of solid propellant fired for 33 seconds, but it was insufficient, taking APPLE only to an orbit of 31,000 by 35,800 km. The 16 small thrusters designed for attitude control and station-keeping were used to make up the deficit.[695] This was the first time an Indian-built satellite was successfully moved by ISRO from GTO to GEO.

  Once in GEO, APPLE experienced another problem. When the command was issued to deploy the two solar panels, only one deployed. Following unsuccessful attempts (spinning, de-spinning and selective heating) to release the stuck solar panel, it was decided to proceed with the mission using the reduced power of 140 instead of 240 watts. In addition to the loss of power, APPLE's ability to dissipate internally generated heat was limited by the solar panel in its stowed position. Consequently, some of the internal subsystems were operating at a high temperature of 50°C, close to their operational limit.

  This was of particular concern during the periods of equinoxes in March and September when APPLE would receive maximum solar radiation. To prevent damage from overheating, ISRO engineers would change APPLE’s orientation for four hours daily during these critical days to help reduce the internal temperature. This was done at night to minimise operational impact.[696] Despite the additional demands on fuel for these unplanned manoeuvres, APPLE exceeded its target operating lifetime of two years by three months. On 13 August 1981, the Indian Prime Minister symbolically handed over APPLE to the Department of Telecommunications from an ISRO ground station in New Delhi. During the event transmitted live using APPLE, she thanked the ISRO staff watching at the SAC in Ahmedabad. During its 27 months of active operations, APPLE was used to conduct experiments, provide live TV coverage of national events (such as the Indian Air Force (IAF) Fire Power Demonstration), transmit educational courses, as well as broadcast 600 hours of TV programmes.[697]

  In the haste to get APPLE operational, the APPLE Mission Control Centre was established as part of the ISTRAC at Sriharikota. Post APPLE, this facility was moved to Bangalore. The total number of staff at ISAC increased to beyond 600. To accommodate them and prepare for the additional growth that INSAT-2 would demand, funding was made available to move ISAC from leased units in an industrial estate to a new purpose-built centre near the old Bangalore airport where it remains today.[698] The overall cost of APPLE, including the launch and communication support service, was estimated to be about Rs.12 crore ($15 million). In practical terms, the value of APPLE to ISRO was much more. APPLE validated ISRO and its engineers’ capability to operate communication satellites in GEO from the associated ground-based infrastructure.

  APPLE provided ISRO with the opportunity to hone skills and technologies unique to communication satellites, including raising the orbit from GTO to GEO, using solar panels and 3-axis stabilisation, station-keeping and operating the ground infrastructure necessary to manage the operational services for a communication satellite.[699]As India's first true communication satellite, APPLE was entirely different to Aryabhata in size, function and complexity. APPLE became the test bed that allowed ISRO to learn to design, build, test and operate communication satellites. APPLE's success was the combined effort of a large team of 2,500 engineers, scientists and administrative personnel, with support from industry and institutions. The average age of the team was 27, and just as Rao had discovered with Aryabhata, the absence of
previous experience was not necessarily a disadvantage. If they were not capable of achieving this goal, they did not know it. APPLE was an ideal stepping stone for ISRO’s next major undertaking, the INSAT programme.

  Communication Satellites

  In his 1970 paper, A Profile for the Decade 1970-80, Vikram Sarabhai asserted “A most important practical application of space research is the use of satellites for telecommunications.”[700] ISRO has since then developed and deployed a series of INSAT satellites that has become the touch point through which most Indians receive the benefits of space technology, even if they are unaware that the services they use rely on space assets. The idea of INSAT was first contemplated by Vikram Sarabhai as early as 1968, as recalled by E.V. Chitnis “We were convinced that India should have a satellite INSAT with television communication, telephonic television and meteorology.”[701] The first public announcement of INSAT was made by Vikram Sarabhai in his presentation, INSAT, A Strategy for Development, at the Bombay National Electronics Conference in 1970.[702] The vision at this early stage was for INSAT to deliver for India what satellite technology was delivering for developed countries, long-distance telecommunication, meteorological services and television broadcasts.

  Although commercial satellite TV services were available from the 1960s, the cost for private users was prohibitive even for many in the developed nations. A satellite was an elegant alternative to the complex, expensive and time-consuming traditional network of TV antennas on the ground. With its unique location in orbit, a satellite TV broadcast could cover the whole of India from space. For India, with its huge and varied landmass, skipping this traditional network of antennas and going straight to satellite TV transmission made practical sense and was consistent with Bhabha and Sarabhai’s vision. By leapfrogging some of the incremental steps in the technological evolution, India could catch up with the pace of development in the West.

  India got first-hand experience in satellite-based TV broadcast through the SITE, a pilot project supported by NASA to deliver educational satellite TV programmes to rural Indian villages. This ran for a year between 1 August 1975 and 31 July 1976. An unintended (at least from India’s perspective) consequence of SITE was to raise India’s expectation that India's INSAT would be modelled on ATS-6, that is, have the capability to transmit TV broadcasts and provide national telecommunication, as well as meteorological services. At the time, ATS-6 was a state-of-the-art spacecraft built by the most advanced space agency in the world, and ISRO was the newest kid on the block.

  INSAT 1 Series

  A technical specification for INSAT came out of an ISRO scientists interdepartmental meeting in Ahmedabad in 1972.[703] The prevailing approach was to deliver each function, telecommunication, TV broadcast and meteorology, through a dedicated satellite. The INSAT design combined all three into one, cutting duplicate costs, including that of launch. In part, the complex design reflected the interests of three government departments, Department of Telecommunication, responsible for telephony; AIR, responsible for TV and radio broadcasts; and the Department of Civil Aviation, responsible for meteorology. These government departments were funding it, and each one wanted INSAT to satisfy its respective operational needs. Described as a “crowded Indian bus”, INSAT was forced to serve three key roles simultaneously.[704] They included: (i) telecommunication services for mainland India and offshore islands (ii) DTH television and radio and (iii) meteorological full Earth images every half hour with up to 2.5 km resolution using visible and infrared sensors.

  Communication and TV broadcast functions were readily accepted. However, the benefits of a meteorological payload were not immediately clear. Given that India’s agriculture contributed 50% of its gross national product and 10% of that was lost annually “due to bad weather, unseasonal rain and wrong forecasting”,[705] the significance of monitoring the weather from space was soon recognised, and a meteorological payload was also included. Consequently, INSAT was the most complex single non-military satellite designed at the time.

  Building and operating something as large and sophisticated as INSAT was a new venture for ISRO. Although ISRO had built and operated satellites, like Aryabhata and Bhaskara 1 and 2, INSAT was too large and sophisticated to build or launch. In 1983, ISRO’s first launch vehicle, SLV-3, with a very simple solid-fuel design had demonstrated that it could place a 40-kg satellite in LEO. However, INSAT-1A and 1B with a mass of 1,152 kg each were well outside ISRO’s capability to launch to GEO. PSLV was still over a decade away. A third party would have to be engaged on a commercial basis to get INSAT started.

  Initially, ISRO procured consultancy from ESA in drafting the Request for Proposal, which was issued at the end of 1977 to global vendors for tender. The key payloads included:

  Two high-power transponders for television broadcasting to community TV sets, distribution of TV programmes for rebroadcasting and radio networking.

  Twelve transponders for telecommunications.

  Meteorological EO instrument (VHRR)for imaging the Earth in the visible (2.5-km resolution) and thermal infrared (10.5-km resolution) spectra and measuring wind speeds as low as 3 miles/s.

  Data relay transponder for meteorological data collection from unattended data-collection platforms.[706]

  Two vendors responded to India’s tender, Hughes Aircraft Corporation and Ford Aerospace and Communication Corporation (FACC). Ford was selected, and an agreement was signed at the Indian Embassy in Washington DC in July 1978 for INSAT-1A to be delivered 28 months later and INSAT-1B a year after that. The cost of the two satellites excluding launch was $60.7 million (Rs.50.5 crore).[707] Throughout its short history, the Indian space programme had always practised a buy, learn and then build strategy. ISRO built its first solid-stage launcher, SLV-3, with assistance from NASA, its liquid-fuel engine technology came from France and a limited cryogenic-engine technology from the USSR. The agreement with FACC had no element of technology transfer, but it did incorporate training to allow ISRO engineers to manage and operate the satellites in orbit, once they were launched. Gaining this knowledge on how to operate satellites in space was a key element in ISRO's plans for self-sufficiency.

  The satellites would be launched from the US either on a Delta rocket or on the Space Shuttle, which in the late 1970s was concluding its testing phase and approaching the first launch. The final specification to which FACC built INSAT-1A included:

  Mass at launch: 1,152 kg

  Expected operational lifetime: 7 years

  Instruments in payload: for communication, meteorology and TV and radio broadcasting services

  Stabilisation: 3-axis stabilised

  Power: deployable solar arrays

  Orbital location: 74°Eat GEO

  Launch: from the US in April 1982 using Delta 3920 launch vehicle

  During the handover phase of INSAT, 25 Ford Aerospace engineers temporarily relocated to ISRO’s MCF in Hassan 200 km west of Bangalore.[708] Following launch on 10 April 1982 from Cape Canaveral, INSAT-1A was successfully piloted by the FACC and ISRO engineers to its designated position of 74°E in GEO with a plan to gradually test and commission all the onboard systems. INSAT-1A was formally commissioned in June, and for a short time, it operated successfully. However, it soon developed issues. INSAT-1A had solar panels on one side, so it required a long boom on the opposite side (called a solar sail) for balance. Despite successfully deploying the solar sail and resolving a problem with an antenna, INSAT-1A lost its orientation. To regain control, the onboard thrusters of the RCS were fired to re-orientate the spacecraft. A faulty propellant valve failed to close after the burn and unused fuel leaked out. Eventually, the entire supply of fuel was exhausted, something from which the spacecraft could not recover. INSAT-1A was deemed to have failed and was officially deactivated on 6 September 1982. The cost of INSAT-1A and its launch was insured, and ISRO recovered the associated costs.[709]

  In contrast, INSAT-1B was an outstanding success. With it, India started to receive the sp
ace-based services that ISRO’s founders had envisaged two decades earlier. It was launched at night on 30 August 1983 by the Space Shuttle STS-8. The Space Shuttle’s first night launch was driven by INSAT-1B’s requirements.[710] In the attempt to draw customers away from ESA’s Ariane launcher, the US offered a heavily discounted launch price on the Space Shuttle, and India took full advantage. Despite initial problems with the deployment of solar panels and the solar sail, INSAT-1B was declared fully operational in October 1983. During the first two years of INSAT-1B’s operation, ISRO consolidated its ground infrastructure and built up the technical skills of its engineers in operating spacecraft in GEO. INSAT-1B introduced to India the nationwide space-based services common today, including:

  Increased capacity for long-distance telephone calls: 4,000 two-way voice circuits for 70 long-distance telecommunication routes.

  High-speed communication for commercial entities, such as The Hindu newspaper, Oil and Gas Commission and the National Thermal Power Corporation.

  An experimental satellite-based telegraphy network for rural locations in the north-eastern India

  Nationwide communication services: 400 Earth stations provided communication across India for isolated communities, including offshore islands.

  National weather service: a collection of meteorological data centres with a primary centre in New Delhi and 22 secondary centres across India distributed meteorological information, including wind and cloud cover over land and the Indian Ocean, for farming, transport, fishing communities and the general public daily. Subsequently, this data supported monsoon modelling and prediction.