It promises to be a historical Indian space mission for three reasons on September 26. It will be the first time that a satellite, Pratham, designed and developed by the students of IIT-Bombay will be launched. Second, only 18 days after successfully launching a weather satellite, INSAT-3DR, another one, ScatSat-1, will be placed in orbit for the first time.

Third, in its 23-year-old history, it will be the first time that the highly proven four-stage PSLV will be launching satellites into two different orbits. For Monday's flight the launcher will be the advanced version of the PSLV called the PSLV-XL.

ScatSat-1 with a five-year mission span will be used for ocean and weather-related studies. The lift off is at 9.12 am from the Satish Dhawan Space Centre, Sriharikota. Apart from Pratham, the other co-passenger satellites are from the US, Canada, Algeria and one of a Bengalaru-based institution. The satellite is called Pisat.

According to Isro, while the main satellite, ScatSat-1, will be placed into a 720-km polar sun synchronous orbit, the remaining ones will go into a 670-km polar sun synchronous orbit. For this complex manoeuvre, Isro had earlier carried out a test of successfully shutting down and restarting the fourth stage engine of the PSLV.

Pratham satellite which weighs around 10 kilograms will be launched using the four stage Polar Satellite Launch Vehicle (PSLV) of ISRO. It will be in the orbit for four months and its main mission is to measure the total electron count in the Ionosphere.