The PSLV rocket -- standing 44.4 metres tall and weighing around 227 tonnes -- took off from the rocket port in Sriharikota in Andhra Pradesh, around 80 km from Chennai.

It rose into the evening skies with fierce orange flames at its tail. Apart from launching the six foreign satellites, ISRO also tested the rocket's fourth stage/engine's ability to restart after it was cut off around 17 minutes into the flight.

Technically speaking, India was testing a multiple burn fuel stage/rocket engine for the first time. "The restart and shut off of the fourth stage engine is done as a first step towards launching multiple satellites but in different orbits," an ISRO official told reporters on the condition of anonymity.

Launching of multiple satellites with a single rocket is nothing new for ISRO and it has been doing that for several years.

The challenge is, however, to launch several satellites at different orbits with one rocket.This is what ISRO plans to test when the PSLV ejects the six Singaporean satellites.

The PSLV rocket is a four-stage/engine rocket powered by solid and liquid fuel alternatively. "Restarting a rocket engine soon after it is shut off is a critical technology that has to be mastered. Once a rocket engine is activated, then the heat generated is very high. The trick is to cool it down in space and to restart it after a short gap," an industry expert said.

Read more: Countdown begins for launch of six Singapore satellites by ISRO

Latest News from World News Desk