India’s Chandrayaan-3 spacecraft, set for launch on Friday, will seek to place a lander about 650km from the lunar south pole for 14 days of studies to probe the moon’s geology and makeup in an unexplored lunar region.

The countdown leading to the scheduled 2.35pm launch on Friday has started, the Indian Space Research Organisation (Isro) said on Thursday, as engineers at the Sriharikota island spaceport remotely tracked myriad systems aboard the spacecraft and the rocket that will ferry it into space.

Chandrayaan-3 — containing a propulsion module, a lander, and a rover — marks Isro’s third lunar exploration mission after Chandrayaan-1, a lunar orbiter, in 2008 and Chandrayaan-2, a lander that crashed on the moon in 2019.

Isro has picked its Launch Vehicle Mark-3 — earlier called the Geosynchronous Satellite Launch Vehicle Mark-3 and the most powerful rocket in its stable — for Chandrayaan-3’s launch.

The spacecraft weighs about 3,895kg at liftoff. The LVM-3 has successfully flown six times since its maiden launch in 2014, carrying heavier payloads into space. In March this year, Isro had used the LVM3 to launch a constellation of satellites for a UK company weighing a total of 5,800kg.

After a circuitous 40-day journey, Chandrayaan-3 is expected to slip into a lunar orbit and deploy the lander with the rover for a soft landing anywhere within a4.0km by 2.5km strip of lunar surface located between two craters — the Manzinus and the Bouguslawsky.

Scientists who had helped select the proposed landing area have said it meets the requirements of sun illumination, radio communication with the Earth, and sizes of its craters and boulders. The area gets sunlight for 11 to 12 days and the boulders there are smaller than 0.32 metres. The sunlight is needed for solar panels that will power the lander and the rover.

After touchdown, the lander is expected to release the 26kg six-wheeled rover that will explore the lunar terrain near the landing area. Both the lander and rover are designed to remain functional for a full lunar day — or 14 Earth days.

“This is an unexplored area of the moon — there have been no landings at this latitude,” said Anil Bhardwaj, director of the Physical Research Laboratory, Ahmedabad, an Isro centre that developed spacecraft payloads for the studies after the landing.

Among the planned experiments is one that will use a needle-like thermometer that will be inserted up to 10cm into the lunar surface to study its heat transfer properties. Another payload will measure seismicity around the landing site. Bhardwaj said studies on heat transfer close to the surface have not been conducted earlier.

The instruments are expected to yield fresh insights into lunar geology and data on heat, if any, from the moon’s interior. Two other instruments, called spectroscopes, on the rover will probe the chemical and mineral composition of the lunar surface and rocks near the landing area.