The Indian Space Research Organisation began a 28-hour countdown for the launch of PSLV-C40/Cartosat 2 Series satellite mission+ at 5.29am on Thursday, according to an update on ISRO's  website.

The countdown started after the Mission Readiness Review (MRR) committee and Launch Authorisation Board (LAB) gave the clearance on Wednesday.

On Friday, when PSLV-C40 takes off on its 42nd flight, it will once again demonstrate the multiple-burn technology where the fourth stage engine will be ignited and shut off four times to place 31 satellites, including small ones, in different orbits. Isro has demonstrated the technology in three previous missions.

Placing satellites in different orbits through a single rocket will save money and help launch more commercial satellites. 

"PSLV launches usually last for 20 to 25 minutes. But this launch lasted for more than an hour. It is almost like having two separate launches," said B Jayakumar, during the launch of PSLVC35 in September 2016, where the multiple burn technology was demonstrated.