A PSLV launch vehicle taking off from India's SHAR spaceport

by Vidya Sagar Reddy

The Indian Space Research Organisation (ISRO) recently launched the replacement satellite for the Indian Regional Navigation Satellite System (IRNSS). This launch happened even as ISRO is trying to re-establish communication with the launched GSAT-6A communications satellite. While the IRNSS space segment is in place, India still has to wait a few months more before utilising it as the ground segment and receivers are yet to be deployed. Also, it remains to be seen if ISRO will order more spare satellites as the budgeted ones are already used up.

The IRNSS is being developed with the aim of providing positioning and navigation services to India’s civilians and strategic users. It covers the Indian mainland and an area within 1,500 kilometres from the country’s borders. This footprint is significant for enhancing regional trade and security. India has welcomed its neighbouring countries to utilise this service free of charge under the Navigation with Indian Constellation (NAVIC) project. It will revolutionise transportation, finance, land surveying, resource management, construction activities, disaster management and a variety of commercial and national security activities.

The IRNSS project had begun with the construction of the space segment in 2013 when the first satellite IRNSS-1A was launched and the seventh and last satellite was placed in orbit in 2016. With the space segment complete, ISRO had set out to calibrate the system. The CSIR-National Physical Laboratory is helping with synchronising atomic clocks onboard the satellites with Indian Standard Time (IST). A variety of receivers are being developed for providing information and services based on this system. Educational institutions also became part of this project, helping ISRO validate the system at various geographic locations of the country.

Unfortunately, IRNSS-1A went out of service as all three of its onboard atomic clocks failed. The clocks are at the core of the navigation system, which sends out precise time signals that are used by terrestrial receivers to plot their position. ISRO had acquired these clocks from a European company which had supplied them also to the Galileo global navigation system being developed by Europe. The European Space Agency encountered a similar problem. The failure of hardware necessitated replacing the IRNSS-1A satellite with corrected clocks.

ISRO made a provision for two spare satellites while designing the IRNSS project worth Rs 1,420 crore. The organisation has involved a consortium of small and medium companies, led by Alpha Design Technologies to perform Assembly, Integration and Testing (AIT) on the satellites, setting into motion its designs for industry led satellite manufacturing. The first replacement satellite IRNSS-1H has been constructed with ISRO handholding the industry consortium and was launched in 2017.

However, the PSLV payload fairing failed to separate trapping the satellite inside. This was the first PSLV failure in years and only the second complete failure. It took about four months to restart PSLV launches, but it had reacquired the success streak. ISRO had launched a Cartosat-2 satellite along with 30 co-passenger satellites in January before attempting to launch the second replacement satellite IRNSS-1I. The satellite will join its peers, operating in full capacity in about a month. This launch is a welcome relief as ISRO is struggling to reestablish communication with the recently launched GSAT-6A communications satellite, using the Geosynchronous Satellite Launch Vehicle (GSLV) Mk II. Communication link was lost after the second orbit-raising maneuver as the satellite went into a safe mode.

The third and final orbit raising maneuver of IRNSS-1I was declared successful by ISRO a few hours back. However, the ground segment and users receivers are yet to be deployed, adding more delays to operationalising the system. The Comptroller and Auditor General has remarked that about Rs 2,400 crore was spent already on the project against the sanctioned Rs 1,420 crore. It has noted the laxities in executing relevant contracts, saying the delays were attributable to lack of coordination. The delay in using the system has effectively reduced the workable lifespan of satellites to eight years from twelve.

Post the launch, ISRO noted that it had welcomed industry participation in manufacturing of receivers, but the response was muted owing to high input costs. Therefore, ISRO had developed the chips and manufacturing of certain components was ordered to an American company.

In addition, it has to be noted that ISRO does not possess more spare satellites in case of an emergency replacement. Two spares are provisioned within the budget which are meant to be used if the in-space satellites become dysfunctional. That could happen because of nearing lifespan or a critical event forcing it out of commission, factors that cannot be fully controlled. On the contrary, both the atomic clocks as well as the launch vehicle are under ISRO’s quality control. Now that the spares have been used up, there is no provision to cater for externalities and outer space is unforgiving. Even as these issues are yet to be resolved, ISRO informed that the second phase of IRNSS programme is under consideration. The satellites under the next phase are expected to host India made atomic clocks. The launch of IRNSS-1I raises new questions even as it tries to resolve older problems.