Miles to go
For India, space is not the final frontier to be conquered. The country’s performance in solving mundane problems such as poverty, illiteracy and malnutrition may be dismal, but its space programme is soaring high. Its latest achievement: the May 5, 2005, launch of Cartosat-1, a satellite for mapmaking, with a 2.5 metre resolution. The 1,560 kilogramme (kg) Cartosat is the only satellite in the world with two panchromatic cameras positioned so as to measure even the elevation of the terrain mapped, allowing almost instant generation of 3-dimensional maps.
The satellite can map the entire country in just 180 days, providing images clear enough for individual buildings to be identified.
Cartosat is India’s 35th satellite; the first was Aryabhatta, launched in 1975. A satellite has an average life span of 7-12 years depending on its functions.
At present, 15 Indian satellites are in orbit, of which as many as 10 have been launched in the last five years. Simultaneously, India has perfected satellite launch technology — it can now inject a satellite weighing up to 2,000 kg into any orbit. This capability has been used to launch satellites even for other countries such as Germany, Belgium and South Korea. Satellite communication is crucial in this era of digital convergence, which is why the governments in 28 countries invested as much as us$46.3 billion (nearly Rs 2,00,000 crore) in space in 2004, says a report, World Prospects for Government Space Markets 2005, by Euroconsult, a private firm.
With a share of Rs 2,540 crore, India was the seventh biggest investor. In the 2005-2006 Union budget, the allocation for space is 24 per cent more, taking the total figure to Rs 3,148 crore. India has spent Rs 25,660 crore since 1962 on its space programme, according to official figures.
Unlike advanced nations, India spends these funds not just on research, but also on launching satellites for basic telecom and broadcasting services. In the West, private satellite vendors largely provide for such activities . But the Indian Space Research Organisation (ISRO) designs, develops and launches satellites that are used both by state-owned public service providers and private companies. Its mandate also includes launching satellites, such as Edusat and Gramsat, to enable airing programmes targeted at the rural population on subjects such as health, education and agriculture.
Insat and IRS
Cartosat is the latest in the series called the Indian Remote Sensing (IRS) satellites. The other series of satellites is the Indian National Satellites (Insat). These two series account for the bulk of the Indian satellites — 10 in IRS and 14 in Insat.
A satellite can either be geo-synchronous or sun-synchronous. The former remains stationary in relation to the earth at an altitude of 36,000 kilometres (km) while the latter is located about 500-1,000 km away and moves as the sun appears to (from earth) every 24 hours. Satellites meant to provide observation data, such as the IRS satellites, are sun-synchronous.
Geo-synchronous satellites are mainly used for communications — receiving/transmitting television, telephone and radio signals. The Insat satellites are in this category. With the first of the series launched in 1983, Insat satellites have been singularly responsible for taking television and telephone to almost 90 per cent of the country. Some also carry instruments to gather meteorological data for use in short- and medium-range weather forecasting, such as to track cyclones.
All geo-synchronous satellites function through devices called transponders, which both receive and send messages in the form of electromagnetic signals. Each transponder tracks signals within a specified frequency range and has a typical capacity of 36 megahertz, which is enough to support as many as 12 digital television channels. At present, India has a total of 143 transponders on its satellites in orbit.
Earlier, the transponders worked mainly within two ranges of frequencies referred to as the s band and the c band. But as the need for point-to-point communications grew, the higher frequency bands such as the k u band (see Glossary) became popular. An increasing number of transponders nowadays are in the k u band, which is the most suitable for direct-to-home (DTH) telecasts and also for the fast-growing closed user group services such as the Very Small Aperture Terminals (V-SATS).
isro transponders were used solely by the department of telecommunications (dot) and the Union ministry of information and broadcasting (i & b), till the Union government adopted a new Satcom Policy in 2000, allowing the private sector access to Insat satellites. Today, 44 of the 143 transponders available with isro are leased out to the private sector — for tv, telecommunications and v-sats.
As many as 13 transponders are with private tv channels, which are demanding more. “We have a heavy demand for dth from Star tv, Sun tv and many other tv channels,” says isro chief G Madhavan Nair.
“The 143 transponders that we have just make both ends meet. If I don’t put three space craft (satellites) on schedule next, everything will come to a halt,” he adds. Anticipating the growing demand, the 10th Five Year Plan has set a target of 235 transponders by 2006-2007.
In the field of telecommunications, the public sector Videsh Sanchar Nigam Limited continues to be a major satellite user. The opening up of national long-distance and international long-distance telecommunications to the private sector since the late 1990s also increased satellite usage.
Thanks to technology and policy changes, and falling bandwidth prices, the v-sat segment is poised for a boom. Capable of providing highly-reliable point-to-point communications, even from remote places, v-sat is especially popular among business groups. India has about 45,000 v-sat users, up five times since 2001, according to a recent report of the v-sat Operators Association of India.
As the demand for transponders grew, isro effected a paradigm shift in its strategy — from multi-purpose satellites (a single satellite carrying payloads for communication, broadcasting and meteorological applications) to ones dedicated to a specific area such as Insat-3 b for communications and Insat-3 d (later renamed Kalpana-1) for meteorological applications.
The design for a multi-purpose satellite allows only one solar array, which limits the total power availability. Dedicated telecom satellites, with transponders on high-frequency band such as the k u band, however, require greater on-board power — either another solar array or high-power devices such as the travelling wave tube amplifiers, which require large heat dissipation systems. With either option, the result is an increase in the overall satellite mass. It is predicted by 2005, nearly 50 per cent of the satellites launched will weigh more than 4,000 kg.
“Specific applications have increased manifold. Earlier, expectations from Insat-1 a were not high — it had just meteorological and telecommunication instruments, but now we need exclusive communication satellites. The transponder demand for day-to-day communication process is increasing rapidly,” says Nair. Insat-1 a, the first in the series, weighed a mere 1,200 kg. But Insat–4 a (scheduled for launch later this year) will have 24 transponders (12 each in c band and k u band) and weigh about 3,100 kg.
“We used to have a hand-to-mouth existence but since the last one year there has been a turn around with the launch of Insat-3 e,” says Sridhara Murthy, executive director, Antrix Corporation, the commercial arm of isro. The growing demand for space services is reflected in Antrix’s rising annual revenue, which increased from Rs 40 crore to Rs 370 crore over the last five years.
Even though isro’s capacity to build and launch satellites has improved over the years, there have been major slip-ups in the utilisation of these precious, nonrenewable resources. On the other hand, isro officials say India is heading for a transponder shortage. Can India afford underutilisation of a resource whose shortage is imminent?