The planned launch of satellites in the coming year and beyond by the ISRO does not include small satellites.
The GISAT-1 is a heavy Earth Observation (EO) satellite developed by the Indian Space Research Organisation (ISRO) is due to be launched from aboard the Geosynchronous Launch Vehicle (GSLV) F10 on 5 March 2020. If all goes well, the over 2.2 tonne satellite will enable India with imagery related to weather, oceanography, meteorology, disaster warning, and equipped to perform EO missions with high temporal resolution, but not spatial resolution. We will return in a moment to the distinction between two to see their relative strengths and weaknesses and evaluate why India needs more satellites for EO in Low Earth Orbit (LEO). As the GISAT-1 satellite is going to be injected in to geostationary orbit, the orbital slot provides wide coverage enabling the user of the satellite the capacity to undertake monitoring of weather patterns with high frequency and on an extensive scale according to the ISRO. Developing a satellite of this kind will enable almost round the clock coverage of the weather over a large geographic area, but the GISAT’s spectral resolution cannot penetrate cloud cover which in any case is not necessary given its orbital destination is GSO and monitoring the weather does not require high spatial resolution.
While GISAT type satellites are necessary, they are insufficient to meet the specifically defence-related challenges the country faces. To be sure, the development of dedicated constellation of radar satellites is crucial for India’s national security. The ISRO launched the X-Band Synthetic Aperture Radar (SAR) satellite RISAT 2B EO satellite in May 2019 and in December of the same year the RISAT 2BR1 was launched, providing a significant jump in India’s capacity for surveillance missions against Pakistan, which is home to terrorist camps that it sponsors. X-band SARs are crucial, because they are not subject to atmospheric interference as other radars and frequencies are operating at a frequency below 10 GHz. The X band has a short wavelength ideal for radar applications as it helps provide high-resolution imagery to identify and discriminate targets.
Further, beyond Pakistan, India will also need to keep an eye on China if not for monitoring terror camps in China, but ultimately for monitoring ground and aircraft deployments across the Tibetan Autonomous Region (TAR). Each of these two radar satellites do provide at least to 2-3 revisit rates a day and since they are deployed in LEO they provide high 1 meter resolution imagery that can penetrate cloud cover and provide surveillance in all weather conditions. Apart from tracking and identifying targets, these satellites would be very crucial in the event of another Balakot-like airstrike, particularly in assessing the damage done to targets and the imperative to release imagery related intelligence of the target’s destruction. This will help stanch speculation about the veracity of any future attacks, when India undertakes them, from airborne platforms. Nevertheless, equally important for India are ocean surveillance satellites for collecting Signals Intelligence (SIGINT). These satellites, which are generally geared for Electronic Intelligence (ELINT), enable detection of ships and aircraft from their radio transmissions. The People’s Republic of China already operates the Yaogan 9 satellites. These satellites while not necessarily in LEO are all deployed in 63.4 inclination ideal for Remote Sensing (RS). Built by the China Academy of Space Technology (CAST), they operate in triplets and by way of triangulation detect position and origins of transmissions. They are similar to the erstwhile American Parcae National Ocean Surveillance Satellites (NOSS).
India for its part, need to look beyond heavier satellites, not to dispense with them, but to supplement them with smaller spacecraft. Thus, while the current RISAT spacecraft are deployed in LEO, there is a need for India to develop a constellation of Small Satellites (SmSats) that deliver for military related missions. The planned launch of satellites in the coming year and beyond by the ISRO does not include small satellites for this purpose. A LEO-based SmSat EO capability is also likely to generate significant military surveillance value for the country. Why are SmSats important and why should Research and Development (R&D) investment in them be considered an imperative? They are consequential for several reasons to the extent that they are easier to manufacture, handle and ultimately launch. However, as we have already observed, a spacecraft equipped with an SAR capability can provide all weather and night-time surveillance and intelligence. According to one Japanese study, a SmSat capable of performing SAR missions would be ideal. In order to develop such a satellite system, a SmSat with an SAR capability; several challenges need to be addressed. As the study noted, the first being, the high power consumption of X-band SAR, the second, reduction in the thermal deformity of antenna panel, thirdly, positioning the spacecraft and the SAR accurately at ground targets and finally, Electromagnetic Compatibility (EMC) caused by high power and heat management. In order overcome the first challenge, a lithium ion battery needs to be able supply 1,000 MW of power for a short period. To overcome the second challenge, the SAR antenna panel need to be directed at the earth during the night to secure infrared thermal energy from the earth and to reduce thermal deformation of the SAR antenna panel. Thirdly, controlling the satellite’ attitude is crucial if detection with pinpoint accuracy is to be made for an observation. Finally, as the study showed, the EMC problem needs to address high power consumption. Normally, EMC testing is undertaken to ascertain whether the device or system is capable of operating within its intended environment and secondly whether it will cause problems to other electronic and electrical devices in its vicinity.
ISRO has developed lithium Ion (Li-On) battery technology with a range between 1.5 Amp Hours (AH) to 100 Ah. However, the Japanese study provides pointers to overcome the problem. ISRO is in the middle of transferring the Li-On technology to the private sector. It is, however, premature to conclude that the space agency has overcome all its challenges to be fully confident or that it can integrate X-band SAR into SmSats. Nevertheless, this should be the eventual goal, as India ought to move towards a distributed space borne surveillance capability.
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Kartik Bommakanti is a Senior Fellow with the Strategic Studies Programme. Kartik specialises in space military issues and his research is primarily centred on the ...Read More +