Just before midnight on Thursday, the Indian Space Research Organisation (ISRO) will launch its 46th flight of Polar Satellite Launch Vehicle (PSLV-C44), to put into space Microsat-R, an imaging satellite and Kalamsat, a communication satellite developed by students, from the Satish Dhawan Space Centre in Sriharikota.The launch at 11:37 pm is said to be unique as PSLV-C44 fourth stage will be re-used automatically to launch Kalamsat payload and Microsat-R satellite into space from the First Launch Pad (FLP). PSLV is a four-stage launch vehicle with alternating solid and liquid stages. The PSLV with two strap-on configuration has been identified for this mission and the configuration is designated as PSLV-DL. PSLV-C44 is the first mission of PSLV-DL and is a new variant of PSLV.