Which of the following is a satellite specifically for navigation?

Option 1 -> GSAT-7A is a military communication satellite for the Indian Air Force, not for navigation.

Option 2 -> GAGAN (GPS Aided Geo Augmented Navigation) is India's satellite-based augmentation system specifically designed to improve GPS accuracy for navigation, particularly for civil aviation.

Option 3 -> GSAT-17 is a communication satellite for telecommunication services, not navigation.

Option 4 -> Chandrayaan-1 was India's first lunar exploration mission and orbiter, not a navigation satellite.

Hence, Option 2 (GAGAN) -> GAGAN is specifically developed as a satellite-based navigation system to provide accurate positioning and timing services over Indian airspace and surrounding regions, meeting international civil aviation requirements -> correct