New Delhi, Jan. 15 -- India's bet to open spacetech to private companies five years ago has spawned startups that are already earning millions of dollars by sharing agriculture and climate data collected by the satellites they launched. These ventures are pivoting towards a new lucrative business: defence surveillance.

Google-backed satellite imaging startup Pixxel and its cross-town peer Digantara target at least half of their business by launching satellites for defence forces in India and overseas, according to their top executives. Even rocket builder Skyroot Aerospace and multiple smaller startups hope to tap such contracts.

India's private space economy revenue is expected to surge more than fivefold over the next eight years from...