Space network guides Chandrayaan’s precise orbit around earth


Bangalore : The precise orbiting of India’s first lunar spacecraft Chandrayaan-1 around the earth is being monitored by the telemetry, tracking and command network (Istrac) of the Indian Space Research Organisation (ISRO), a top official said here Friday.

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“Very precise orbit determination of Chandrayaan is in progress for planning its next manoeuvre over the next two days. Health parameters of the lunar spacecraft are also being evaluated,” ISRO director S. Satish told IANS.

With no orbit-raising planned Friday, the 1380 kg spacecraft is spinning around the earth elliptically at an apogee (farthest from earth) of 37,902 km and a perigee (closest to earth) of 305 km.

“In this orbit, the spacecraft goes around the earth once in 11 hours and 5 minutes. Its health is perfectly all right and is able to send/receive signals at regular intervals from our network and ground stations,” Satish said.

ISRO’s deep space network (DSN) at Bylalu, about 40 km from this tech hub, is also involved in the manoeuvring exercise. It tracked the spacecraft and received signals in s and x band and sent commands in turn.

“The actual role of DSN will come into play when the spacecraft crosses 100,000 km (apogee) from the earth when its signals become feeble and time-consuming,” the official said.

Chandrayaan launched Oct 22 at 6:22 a.m. onboard the 316-tonne polar satellite launch vehicle (PSLV-C11) from the Satish Dhawan Space Centre at Sriharikota spaceport, about 80 km north of Chennai.

The spacecraft is expected to enter the lunar orbit Nov 3 when the moon will be about 500 km away (perigee).

A series of complex manoeuvres in the final phase will put Chandrayaan in the final orbit Nov 8, which will be about 100 km from the moon’s surface.

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 the various centres of the state-run ISRO.