News 
BENGALURU: Chandrayaan-4 India’s planned lunar sample return mission that aims to soft land near the Moon’s south pole, collect samples from the lunar surface, and return them to Earth for analysis will have a mass of approximately 9,200kg compared to Chandrayaan-3’s 3,900kg.
Since Isro’s current capability to lift payloads to geotransfer orbit (GTO) is limited to about 4,500 kg, the mission will require two separate launches: Two modules will be launched in one stack, three modules will be launched in another stack. These launches will be conducted using the LVM-3 vehicle with a one-month gap between them.
In an exclusive interview to TOI, Isro chairman V Narayanan explained how multiple dockings will be carried out, and also gave details on Chandrayaan-5, the joint mission with Japan, also called Lupex (Lunar Polar Exploration Mission).
Status & mission sequence
“We have completed the configuration design and now the design of various subsystems is ongoing,” Narayanan said, adding that the mission architecture involves multiple docking and undocking manoeuvres in both Earth and lunar orbits.
According to Narayanan, after the two launches, the initial docking of modules will occur in Earth orbit. A propulsion module will then transport the spacecraft to lunar orbit (separating at around 1-lakh-km from Moon). In the lunar orbit, four modules will remain after propulsion module separation and two modules, including the ascending module will separate and land on Moon.
After sample collection, one module will return and dock with the remaining modules in lunar orbit, the sample will be transferred to a re-entry module and the re-entry module will return to Earth with the samples.
“The mission requires development of new technologies, including a high-capacity propulsion system, specialised payloads, and robotic arms for sample collection. Work on all of this is going on,” Narayanan said.
Lupex marches on
Elaborating on Lupex, which India will designate as Chandrayaan-5, Narayanan said the landing mass of the spacecraft will be 6,200kg and the rover on Lupex will weigh 350-400kg compared to Chandrayaan-3’s 26kg.
For Lupex, Japan will be responsible for the development and operation of the launch vehicle and rover, while India will be responsible for the development and operation of the lander. Aside from Indian and Japanese instruments, Lupex will also carry American, and European instruments.
“After the project was approved, configuration study has been completed, and teams are now working on hardware design and development,” Narayanan said. TOI had reported earlier that Lupex will need Isro to work on a heavier lander engine, which Narayanan confirmed. He said work had already begun on that.
In the first week of Feb, Jaxa, Japan’s space agency updated its mission page on Lupex to add details about the rover payloads. As per Jaxa, the rover will carry seven main payloads.
The first payload, Resource Investigating Water Analyser (REIWA) will have the Lunar Thermogravimetric Analyser (LTGA), Triple-reflection Reflectron (Triton), Aquatic Detector using Optical Resonance (ADORE) and Isro Sample Analysis Package (Isap).
The other six payloads are: Advanced Lunar Imaging Spectrometer (Alis), Neutron Spectrometer (NS), Exospheric Mass Spectrometer for Lupex (EMS-L), Ground Penetrating Radar (GPR), Mid-Infrared Imaging Spectrometer (MIR) and Permittivity and Thermophysical Investigation for Moon’s Aquatic Scout (Prathima).
