Cartosat 2 and ISRO's multiple outreach

December 4, 2017 By Lt. General P.C. Katoch (Retd) Photo(s): By ISRO
By Lt. General P.C. Katoch (Retd)
Former Director General of Information Systems, Indian Army


Cartosat-2 Series Satellite in a clean room at the launch centre

Come later half of December and the Indian Space Research Organization (ISRO) is getting ready to launch the next remote sensing satellite of Cartosat-2 series along with 30 nano satellites of foreign countries. This, after the unsuccessful launch of navigation satellite IRNSS-1H in August this year. The replacement satellite for IRNSS-1A is planned to be launched immediately thereafter. It may be recalled that the three atomic clocks of IRNSS-1A, meant to provide precise location data, had stopped working last year. IRNSS-1A was the first navigation satellite launched by India. Both these launches will be from the first launch pad at Sriharikota as the second launch pad is planned to be used for launching three GSLV rockets, including the Chandrayaan-2 mission in March 2018. The three GSLV launches, will involve two GSLV Mk II and one GSLV Mk III. For the Chandrayaan-2 mission, ISRO is using the heavier GSLV Mk II as the payload includes the orbiter, the lander and the rover, with combined launch mass weight of 3,250 kg. Concurrently, ISRO is also working on developing an indigenous global positioning system (GPS); indigenous regional positioning system named 'Navigation with India Constellation (NavIC), which will be independent of the US clock system. In this context, a MoU was signed between ISRO and the CSIR-National Physical Laboratory (NPL) in August this year for time and frequency traceability services. This will help the indigenous GPS get formally synchronized with the Indian Standard Time (IST) maintained by the Delhi-based National Physical Laboratory (NPL), which is the official timekeeper of India. Indo-US relations are presently at all time high but obviously India cannot keep being dependent on the US clock system. Not many would know that during the Kargil Conflict, the GPS was switched off by the US, causing navigational problems for Indian naval platforms out in the Arabian Sea.

Dependence on foreign clock systems has the danger not only of stopping the GPS, but also feeding of 'wrong' coordinates with adverse operational fallout to the users. Time synchronization is anyway essential for every type of service, be it operations concerning national security, preventing cyber crimes, financial transactions, stock handling, digital archiving, or time stamping. Time has to be extremely accurate since light travels 30 cms in one nanosecond and even a tiny error in the time signal can result in going off course by a very long way. The NPL maintains accuracy of ±20 nanoseconds and thereby gives the most accurate time which is essential for satellite navigation system. It has the "Primary Reference Clock", which is traceable to the Coordinated Universal Time (UTC) provided by International Bureau of Weights and Measures (BIPM) located in Sevres, France. The UTC consists of a time-scale that combines the output of more than 400 highly precise atomic clocks worldwide, including five at the CSIR-NPL. With all the intricacies, it is not that NavIC will get fielded tomorrow.

According to Minister of state for Space and Atomic Energy Jitendra Singh, the NavIC system may take couple of years to become fully operational in the market. He had also informed Parliament in a written reply to a question, saying, "Various types of user receivers are being developed indigenously involving the Indian industry and discussions amongst government departments, user-receiver manufacturers, system integrators and service providers are taking place for the usage of NavIC system." With the global satellite launch market expected to reach $3 billion in next couple of years, ISRO is also planning to outsource the manufacture of satellite launch vehicles, with itself focusing on its primary goal of becoming a leader in the highly-competitive global satellite launch market, particularly for nano- and micro-satellites.

ISRO already uses industry manpower and facilities to build small to mid-sized satellites, ranging from 300 kg to 2,000 kg, for domestic use and export. Outsourcing manufacture of satellite launch vehicles will give maneuverability to ISRO in competing globally, where as thousands of satellites for space-based applications like navigation and surveillance are lined up for launch by 2025, unlike the heavier (+2.5 ton) communication satellite market where ISRO's GSLV seeks to make a mark. Competition is also growing in reducing launch costs, with China also focused on this. With respect to satellite launch vehicles, ISRO is keen on private operators taking over its workhorse Polar Satellite Launch Vehicle (PSLV) program; PSLV having recorded more successful missions (total 39), than any other space agency with comparable launchers. Presently, ISRO is developing a compact booster that can be assembled in 72 hours, compared to 40 day-turnaround for standard PSLV, and can launch payloads up to 700 kg into a near-Earth orbit of 700 km. However, subcontracting private industry to build launchers is a potential game changer that could stimulate R&D and help absorb enterprise and innovation into future ISRO missions. It may be recalled that in June 2016, India launched 20 satellites in one go, which was the maximum ever by ISRO. But within a span of eight months ISRO launched 104 satellites in one go during February this year, creating a world record.

ISRO also became part of a global project that will help bring star travel closer to reality, when its PSLV C38 rocket launched six prototypes of tiny interstellar spacecraft, or 'sprites', into low-earth orbit on June 23 this year; each of these sprites weighing 4gm and are 3.5cm long managing to establish contact with ground stations - becoming the smallest spacecraft ever to do so. These sprites are part of the multi-million dollar 'Breakthrough Starshot' research project funded by Russian technology investor Yuri Milner and supported by cosmologist Stephen Hawking. Successful launch of sprites is seen as a giant step in space technology, sowing the seed for future interstellar missions. Separately, ISRO is also working on its AVATAR – Aerobic Vehicle for Trans-atmospheric Hypersonic Aerospace Transportable Reusable Launch Vehicle (also called AVATAR RLV). AVATAR is an experimental unmanned advanced hypersonic space shuttle. ISRO has consistently made India proud.