The First unmanned earth satellite built India. It was named after prominent Indian astronomer and mathematician of the 5th century AD. The satellite was assembled at Peenya near Bangalore but was launched from the erstwhile Soviet Union by a Russian-made rocket on April 19, 1975. Aryabhata weighed 360 kg and was instrumented to explore conditions in the Earth`s ionosphere, measure neutrons and gamma rays from the Sun and perform investigations in X-ray astronomy. The scientific instruments had to be switched off during the fifth day in orbit because of a failure in the satellite`s electrical power system. Useful information nevertheless was collected during the five days of its operation.