February 1982:the SLV-3 rocket

Since its inception, in 1963, the Indian Space Programme has stressed two main aims:

1. The rapid development of mass communications and education, especially in widely dispersed rural areas.

2. Timely surveying and management of the country’s natural resources.

In keeping with these aims, India has built three satellites for launch by other countries: Aryabhata, Bhaskara and Apple. The first two were launched in 1975 and 1979, respectively,from Kapustin Yar in the Soviet Union on the C-1 Interkosmos launch vehicle. Apple was given a free ride into space by the European Space Agency’s Ariane LO-3 launcher on 19 June 1981.

While Aryabhata was basically a technological test satellite,Bhaskara has, since May 1980, been returning about 10 TV pictures per day of the Indian subcontinent for Earth resources studies, as well as performing other remote sensing activities.

Apple is designed to test the performance of an Indian-built 3-axis stabilised communications satellite stationed in geostationary orbit, and is the forerunner of the Insat 1 and 2 comsats currently being built for India by Ford Aerospace in the USA. Insats 1 and 2 will, following their launches in 1982 and 1983, respectively, provide comsat services for the country as well as conducting meteorological observations.

The SLV-3 launcher

While India has been accepting foreign aicj to launch its satellites, ISRO (Indian Space Research Organisation) has been developing a national launcher which, in its final form, will be capable of launching 5 tonnes into low Earth orbit. The first steps in the programme have seen ISRO fly three of the first development launchers built under this programme.

SLV-3 development began in 1973 with the intended objective of being able to place 140 kg into a 300 x 900 km orbit. The development programme has involved over 46 public and private industries working to develop the hardware and software for the SLV-3.

SLV-3 is a four stage solid propellant rocket 22.7 m high and 1 m in diameter. Take-off weight is about 28 tonnes. The first stage is 10 m long and is powered by a single 255,250 kgf thrust motor. The 6.4 m long second stage single motor has a thrust of 23,500 kgf. The third stage is 2.34 m long and is powered by a single 18,070 kgf thrust motor. The fourth stage motor has a maximum thrust of 2,150 kgf and the stage is 1.5 m long. Control of all stages is by inertial guidance.

More than 85% of the SLV-3’s components were developed in India, including the solid propellants which are said to be comparable with any produced elsewhere. The first stage motor consists of three separate segments, reportedly for ease of manufacture, while the other stages have one-piece motors.

The SLV-3 contains 44 major systems, 250 sub-systems and 10,000 components.

Payload for the three SLV-3s launched to July 1981 were small technological capsules called Rohini satellites. The RS weighed 3 5 kg each, and were spin-stabilised polyhedral shaped capsules whose main function was the monitoring of the performance of the fourth stage of the SLV-3. Other objectives included evaluation of solar panel fabrication technology and the Indian-made solar cells. The third RS also carried a small landmark camera for Earth observations. The camera,with sensors based on charged-couple devices, collected data with a 1 km resolution.

Flight history

The first flight SLV-3 was launched on 10 August 1979 from the launch site at Sriharikota Island, north of Madras. The flight lasted for 317 seconds. Due to a second stage fault (caused by the malfunction of the control system when nitric acid in a solenoid valve drained off) insufficient velocity was obtained to reach orbit and, despite the successful performance of over 70% of the SLV-3 systems, the rocket impacted in the Bay of Bengal some 500 km away from the launch site.

Following fixes to the next vehicle, the second SLV-3, launched 18 July 1980, successfully placed the RS-1 satellite into a 290 x 900 km orbit inclined at 45°. The solar cells developed 3 W of electrical power and the satellite was reported to be spinning at a rate of 165 rpm. Tracking of the satellite was performed by the ISRO stations at Sriharikota and Ahmedabad.

The third SLV-3 flight occurred on 31 May 1981 and placed the 38 kg RSD-1 satellite into a lower orbit than planned - 181 x 364 km instead of 296 x 834 km - which resulted in the satellite re-entering the atmosphere and burning up on 9 June, after 130 revolutions. The lower orbit was apparently the result of anomalies occurring between the third stage separation and fourth stage firing.