NESTLED amid the eucalyptus, cashew and coconut trees of Sriharikota Island on the eastern coast of India, north of Chennai, is a 76-metre steel tower. If all goes to plan, some time in late 2007 the tower will be engulfed in flames as India's first mission to the moon blasts off. Sriharikota will also be the launch site for India's most advanced scientific research satellite, Astrosat. The satellite will measure, among other things, X-ray radiation emitted by matter sucked into black holes and given off at the birth and collision of stars.

But why is India, a country that still has so many development problems on the ground, aiming for the heavens? To Indian scientists, the question is not only patronising of their scientific aspirations, it betrays an ignorance of the Indian space programme's greater purpose and successes against the odds.

India's political leaders say the country cannot afford not to have a space programme. Indira Gandhi, who was India's longest-serving prime minister, believed it was not only important for science, but also vital to India's development.

Take, for example, India's six remote-sensing satellites - the largest such constellation in the world. These monitor the country's land and coastal waters so that scientists can advise rural communities on the location of aquifers and where to find watercourses, suggest to fishermen when to set sail for the best catch, and warn coastal communities of imminent storms (see "Eyes in the sky"). India's seven communication satellites, the biggest civilian system in the Asia-Pacific region, now reach some of the remotest corners of the country, providing television coverage to 90 per cent of the population. The system is also being used to extend remote healthcare services and education to the rural poor.

But it has been a long time coming. When India first detonated a nuclear device in 1974, the US and European nations imposed widespread sanctions to restrict India's access to technologies that could be used to make a nuclear missile. This hobbled the country's rocket development programme and forced the Indian Space Research Organisation (ISRO) to reinvent technologies it could no longer buy. In the long run this has given India an advantage over other countries with aspirations to reach space. Its space programme is already largely self-sufficient and aims to soon be completely independent of foreign support.

It hasn't all been plain sailing. Its first rocket, the Satellite Launch Vehicle, ended up crashing into the Bay of Bengal 5 minutes after launch in 1979. The following year it placed a 40-kilogram remote-sensing satellite into near-Earth orbit, but the satellite's perigee was lower than planned and it entered the atmosphere and burnt up after only 130 orbits. The Augmented Satellite Launch Vehicle followed, and in 1992, after two crashes, it finally succeeded in lifting 150 kilograms to a height of 435 kilometres.

ISRO moved on to the Polar Synchronous Launch Vehicle, designed to carry 1-tonne satellites to a height of nearly 1000 kilometres. Though the first launch in September 1993 crashed, the PSLV has since performed flawlessly, placing seven Indian satellites and four from other countries into orbit. "It is our workhorse," says Madhavan Nair, director of ISRO. In 2003 the rocket was used to launch India's latest remote-sensing satellite, IRS-P6, capable of imaging the Earth's surface to a resolution of 5 metres.

To put its heavier communications satellites into geostationary orbit, India still has to rely on foreign hardware. But that may soon change. ISRO's latest rocket, the Geosynchronous Launch Vehicle (GSLV) is able to lift large satellites into geostationary orbit, 36,000 kilometres up. On 20 September 2004, the GSLV launched the 2-tonne EDUSAT, the world's first satellite dedicated to providing support for educational projects.

One of the GSLV's rocket boosters is a Russian-made cryogenic engine. International sanctions meant India was only allowed to buy engines, not the know-how to design and build them. So for future rockets ISRO engineers are developing their own. Ground tests have been completed and the plan is to launch a completely home-made GSLV-Mark 2 by the end of this year, Nair says.

ISRO is already planning the next-generation GSLV, the Mark 3, which will be powerful enough to launch India's biggest satellites. Nair now has his sights on the commercial market. A launch on GSLV-Mark 3 should cost about half the rate charged by France, the US and Russia, he says.

India's space programme is already a money-earner. ISRO sells infrared images from its remote-sensing satellites to other countries, including the US, where they are used for mapping. And the Technology Experiment Satellite, launched in October 2001, is beaming back images of the Earth's surface with a resolution of 1 metre, though they are not yet available commercially.

Three per cent of ISRO's $3.3 billion 5-year budget is devoted to the planned moon mission. A reconfigured PSLV rocket will lift Chandrayan - "moon vehicle" in Hindi - to 36,000 kilometres, after which the craft's own engines will take it to the moon. Nair says one of the purposes of the mission is to inspire Indian youngsters to take up a career in science.

Chandrayan will create 3D maps of the moon's surface at a resolution of between 5 and 10 metres, something that has never been done before. It will also map the distribution of ilmenite, a mineral that traps helium-3, a possible source of energy for future bases on the moon. No manned missions are planned, but if the trip is successful, robots might be sent up to collect samples.

According to Nair, the Madras School of Economics in Chennai has estimated that ISRO's projects have added between two and three times the organisation's budget to the nation's GDP. Several countries in Africa and Asia are seeking ISRO's help to emulate the model. "India is perhaps the only country where societal needs are met by the space programme in a cost-effective manner and the services are reaching the needy," says Nair.

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