India: Even as it moves into making heavier communication spacecraft weighing 4,000 kg to 6,000 kg, the Indian Space Research Organisation (ISRO) has also firmed up a strategy to a make increasingly smaller satellites for earth observation and scientific, experimental and other missions.
The plan for small satellites is two-pronged and can range from 10 kg ‘micros’ to 300 kg-500 kg ‘minis’. A series of 350-kg ‘mini’ satellites, probably with high resolution cameras and innovative features, will be built in the near future for the ISRO’s own remote-sensing uses.
They will be built on the decade-old IMS-2 platform on which the ISRO Satellite Centre (ISAC) has earlier brought out half a dozen EO (earth observation) satellites.
It also plans to build 10 kg or smaller nano and micro satellites using a 100 kg IMS-1 platform. This will offer ready and reliable micro and nano satellite ‘shells’ on which the Indian Institutes of Technology, universities and even start-ups can put their experimental payloads or devices.
The idea is to encourage users to save time to import a suitable small satellite and instead focus on test novel concepts on the satellites. IMS stands for 80 kg Indian Mini Satellite, launched in 2008.
The 300 kg – 400 kg class may be the new norm in Indian EO. “In future, we may put three EO satellites, each with a mass not more than 350 kg, at a time on a PSLV. They will be for remote sensing, weather or science missions,” ISAC director M. Annadurai told The Hindu. Such a plan, he said, would also need fewer launch vehicles, efforts and time.
Dr. Annadurai said that going small was in tune with the global trend and “a logical extension of what we were already doing a decade ago.”
The ISRO’s own remote-sensing satellites, he said, had been getting progressively smaller, from close to 1,000 kg to the recent 370-kg Scatsat-1 to monitor ocean weather.
Considering the growing interest among universities and start-ups to use sub-100 kg satellites as test beds, the ISAC can readily provide them the basic spacecraft using a “two-stack” configuration somewhat off the shelf. The user can later add a payload or application of 5 kg on to this. Today, university satellites take three years to materialise and involve students from two or three batches.
This affects continuity, quality and interest levels in the teams and risk producing “me-too” satellites with no new ideas. “We want to bridge these gaps,” he said.
Dr. Annadurai said that student satellite projects come up with interesting and relevant experiments and need to be encouraged. One such corelates ionospheric phenomena with impending earthquakes. To lessen debris they could be made to decay faster by putting them at lower 450 km orbits, among others.
The ISRO, too, used small satellites to test its concepts. IMS-1 was the test bed for elements that went into Chandrayaan-1 of 2008.