India's first unmanned spacecraft Chandrayaan-1 descended further into the lunar orbit on Tuesday following the third orbit-reduction manoeuvre, a top space official said in Bangalore.

"The manoeuvre was carried out at 18.30 (IST) for 31 seconds to push the spacecraft into a lower orbit at 102-km periselene (nearest point to moon) and 255-km aposilene (farthest point from moon)," Indian Space Research Organisation (ISRO) director S Satish told IANS.

In the current lower elliptical orbit, the spacecraft will revolve around the moon once in two hours and nine minutes.

Over the next two days, further orbit-reduction exercise will be carried out to move the spacecraft gradually into the designated circular orbit of 100 km from the moon's surface by Thursday.

"In the fourth orbital operation Wednesday, Chandrayaan will be positioned at 101-km periselene and 103-km aposelene and geared up for its final slot in the lunar orbit, which will be about 100-km from the lunar surface," Satish pointed out.

All sub-systems onboard are working normally.

The spacecraft is guided and monitored remotely from the space agency's telemetry, tracking and command network (Istrac) here.

ISRO's deep space network (DSN) at Byalalu, about 40 km from India's tech hub of Bangalore, transmits commands and receives signals from the spacecraft.

ISRO plans to eject the moon impact probe Nov 14-15 from the spacecraft and crash it onto the lunar surface at a designated area, where the Indian tricolour will be "hoisted".

Chandrayaan carries 11 scientific instruments, including six foreign payloads - two from the US, three from the European Space Agency (ESA) and one from Bulgaria. The remaining five are indigenously designed and developed by various centres of the state-run ISRO.

The spacecraft blasted off Oct 22 onboard the 316-tonne polar satellite launch vehicle (PSLV) C11 from the Satish Dhawan Space Centre at the Sriharikota spaceport, about 80 km north of Chennai.