Chandrayaan-3 establishing connection with Chandrayaan-2 is significant. What comes next?

Indian Space Research organisation (ISRO) on Monday said a two-way communication between the Chandrayaan-2 orbiter and Chandrayaan-3's lander module has been established.

"‘Welcome, buddy!’ Ch-2 orbiter formally welcomed Ch-3 LM. Two-way communication between the two is established. MOX has now more routes to reach the LM," the national space agency said in a post on 'X'.

What does Ch-3 and Ch-2 connecting mean?

Chandrayaan-2 is the predecessor of Chandrayaan-3 in India's series of lunar mission. Chandrayaan-2 was launched in 2019. The lander with a rover in its belly crashed into the Moon's surface, failing in its mission to achieve a soft-landing.

ISRO informed that the Chandrayaan-2 orbiter, which has been in the lunar orbit, has established connection with the Chandrayaan-3 lander module Vikram with the rover in its belly. This is essential because now the lander module is connected to the ISRO headquarters in more than one established connections.

As per specifications, in addition to Chandrayaan-2 orbiter, the lander of Chandrayaan-3 has the capability to communicate with the Indian Deep Space Network (IDSN), a network of large antennas and communication facilities operated by ISRO to support the interplanetary spacecraft missions of India, at Byalalu in Ramanagara district, and the 26 kg rover.

The MOX (Mission Operations Complex) is located at ISRO Telemetry, Tracking and Command Network (ISTRAC) in Bengaluru, India. ISRO said in 2019 that due to the precise launch and orbital manoeuvres, the mission life of the orbiter is increased to seven years.

When will Chandrayaan-3 land on Moon?

ISRO said on Sunday the lander module of Chandrayaan-3, the third lunar mission of India, is expected to touch down on the surface of the Moon around 6.04 pm on August 23.

ISRO also said, in an update, that the live telecast of the landing event will begin at 5.20 pm. Live actions will be available on the ISRO website, its YouTube channel, Facebook, and public broadcaster DD National TV. 

What happens next for Chandrayaan-3?

The next task for Chandrayaan-3 lander module Vikram is landing itself on the south pole of the moon. All systems on an Indian spacecraft heading to the moon are working "perfectly" and no contingencies are anticipated on the landing day, the country's space agency said on Monday. 

Notably, rough terrain makes a south pole landing difficult, but making a first landing would be historic. The region's water ice could supply fuel, oxygen and drinking water for future missions.

What happens after Chandrayaan-3 lands?

Once the Lander Module of Chandrayaan-3 reaches the Moon's surface, the lander Vikram will deploy its payloads.

These include Chandra’s Surface Thermophysical Experiment (ChaSTE) for measuring temperature and thermal conductivity. Another payload, the Instrument for Lunar Seismic Activity (ILSA), will measure seismic activity around the landing site. The Langmuir Probe (LP) will estimate plasma density and changes. A passive Laser Retroreflector Array from NASA will be used for lunar laser studies.

The rover Pragyan on the other hand, carries an Alpha Particle X-ray Spectrometer (APXS) and a Laser Induced Breakdown Spectroscope (LIBS) to determine the elements in the landing site's vicinity.

What happens to the propulsion module of Chandrayaan-3?

The Lander Module, which includes the rover Pragyan, was separated from the Propulsion Module within the spacecraft on Thursday.

The Propulsion Module will remain in Moon's orbit for months or years. 

Notably, the Propulsion module has an attached payload known as the Spectro-polarimetry of Habitable Planet Earth (SHAPE), to study Earth's spectral and polarimetric measurements from the moon's orbit. In simpler terms, SHAPE will analyse certain signatures of Earth's light.