Indian space agency ISRO on Monday will, for the first time, be making commercial use of its own multiple burn technology while launching eight satellites - five foreign and three domestic - in different orbits, said a senior official.
Multiple burn technology is the switching off and switching on of a rocket's engine in space.
Vikram Sarabhai Space Centre (VSSC) director K. Sivan said that the 48-and-a-half-hour countdown for the launch of Indian rocket Polar Satellite Launch Vehicle (PSLV) that would carry the eight satellites is progressing smoothly at the rocket port Sriharikota in Andhra Pradesh.
It began on at 8.42 am on Saturday and the rocket is expected to blast off at 9.12 am on Monday.
"We will be using the multiple burn technology for the first time for launching satellites. Earlier we switched off and switched on the fourth stage (engine) of PSLV to test the technology," said Sivan.
He said the first time the multiple burn technology was first tested by ISRO while flying its PSLV rocket on December 16, 2015 and in June 2016, the technology was again demonstrated.
About the challenge to be faced on Monday, Sivan said: "After cutting off the engine, its condition should be brought to such a stage that it could be restarted again. The next challenge is to controlling the engine and bringing it so as to eject the remaining satellites into a different orbit."
He said the rocket has GPS aided navigation system so that data generated by the rocket's inertial navigation system and the one provided by the former will be blended so as to erase and errors and to generate a precise data.
On Monday, a 320 ton PSLV rocket will put its main cargo the 371 kg SCATSAT-1 - for ocean and weather related studies - into a 730 km polar sun synchronous orbit, 17 minutes into the flight.
The remaining seven satellites will be placed in a 689 km polar orbit nearly two hours later.
These include five foreign satellites: three from Algeria (Alsat-1B 103kg, Alsat-2B 117kg, Alsat-1N 7kg), and one each from Canada (NLS-19, 8kg) and US (Pathfinder-44kg).
The two other Indian satellites are: Pratham (10kg) built by Indian Institute of Technology-Bombay and Pisat (5.25 kg) from PES University, Bengaluru and its consortium.
After putting into orbit SCATSAT-1, the rocket's fourth stage or the engine will be shut down and would be restarted and cut off 1 hour 22 minutes twice after the rocket blast off from Sriharikota.
Two hours and 11 minutes into the flight the fourth stage will be restarted. Four minutes later all the seven satellites would be put into their intended orbit.
Sivan said the long-time gap between the cutting off of the engine and its restart is not an issue.
The PSLV rocket is a four stage/engine rocket powered by solid and liquid fuel alternatively.
According to ISRO, SCATSAT-1 is a continuity mission for Oceansat-2 scatterometer to provide wind vector data products for weather forecasting, cyclone detection and tracking services to the users.
The satellite carries Ku-band scatterometer similar to the one flown onboard Oceansat-2.
The mission life of the satellite is five years.