Satellites: navigation, remote sensing and everyday use

Most people never see a satellite, but they use them daily: weather forecasts, television, navigation on a phone, cyclone warnings and crop assessments all depend on spacecraft overhead. India operates two broad families of satellites for these purposes. Communication satellites, in the INSAT and GSAT series, carry television, telephone and data links, especially to remote areas. Earth observation satellites, in the IRS and Cartosat series, photograph the land, oceans and atmosphere in different wavelengths, revealing crops, forests, water bodies, urban growth and disaster damage.

Navigation is a separate capability. NavIC, the Navigation with Indian Constellation, is India's regional satellite navigation system, built around a constellation of seven satellites covering India and the region around it. Like the American GPS, it lets receivers work out their position from satellite signals; unlike GPS, it is under Indian control, which matters for military use, transport and disaster management when access to a foreign system cannot be assumed. NavIC signals are being built into phones and vehicles, though adoption depends on chip support and user demand.

Remote sensing turns images into decisions. Satellite data help forecast crop production, monitor groundwater and forest cover, map flood extent, track cyclones and plan roads and cities. The Bhuvan geo-portal makes much of this data available to government and the public, and state agencies use it for watershed planning, land records and disaster response. The value lies less in the image itself than in the interpretation: trained analysts, ground verification and timely delivery to the officer or farmer who must act.

Satellites also raise governance questions. High-resolution imagery can monitor borders and infrastructure, but it can also raise privacy concerns when it observes private land. Data policy must balance openness, which helps researchers, farmers and businesses, with security, which restricts sensitive imagery. International rules on orbital slots, frequencies and space debris add a further layer: every new satellite must fit into a crowded orbital environment.

The everyday lesson is that space technology is infrastructure. Its benefits arrive not at launch but in the years of data, warnings and connections that follow, and its success should be judged by who uses the data and what decisions improve because of it.