Why Kaveri Engine Failed: In the 1960s, ISRO started to build sound rockets for upper atmosphere research. These sound rockets were simple by nature and go 20–50 kilometres into the atmosphere. Large numbers of sounding rockets have been developed and launched from Thumba Equatorial Rocket Launching Station (TERLS).
ISRO has developed a series of sounding rockets called Rohini series, important among them being RH-200, RH-300 and RH-560, number in the name indicating the diameter of the rocket in mm. These rockets weigh up to few hundreds of kilograms.