Chandrayaan-4 Integrated Module' The LAM of transfer module seen on top and its re-entry cone is shown in golden brown. The ascender-lander-propulsion modules are seen beneath it in downward succession
The plan for a lunar sample return mission was revealed by the director of Space Application Centre (SAC), Nilesh M Desai on 17 November, 2023 during the 62nd foundation ceremony of Indian Institute of Tropical Meteorology (IITM) in Pune.[5] This was confirmed by S. Somanath, the chairman of ISRO during the National Space Science Symposium held in Goa on 26 February 2024.[6] He said that the mission is extremely challenging as it incorporates multiple launches, docking capability and robotic capability. He expressed the confidence buildup over the success of 'hop' operation of the lander and Earth return operation performed by the propulsion module of Chandrayaan-3.[6][7] After the launch of INSAT-3DS, the chairman stated the insufficiency of the rocket capability leading to a 'novel design' for this mission and the secretary of the Department of Space (DoS) said that the mission incorporates 'high-end technology' and it is pending government approval for him to have a final word.[1][8] Somanath stated that the mission demands docking capability both in Earth and lunar orbits and the agency is planning to demonstrate this capability through Space Docking Experiment (SPADEX) which is slated for launch by year end.[2][9]
On 20 August 2024, S. Somanath announced that ISRO had completed the design of both Chandrayaan-4 and LUPEX,[10][11] and is now requesting approval from the government.[12]
Cabinet approval
On 18 September 2024, Chandrayaan-4 received approval from The Union Cabinet, chaired by Prime MinisterNarendra Modi for ₹2,104.06 crore (US$250 million) and is expected to be completed within 36 months.[13][14] The mission will have five modules that will be carried to space on two different launches. The mission is designed to land on the lunar surface, collect samples, store them in a vacuum container, and bring them back. The mission will also see docking and undocking — two spacecraft aligning and coming together in orbit.[15][16]
Objectives
The aim of the mission is to collect samples from the lunar surface and bring the samples safely to Earth for scientific studies. The objectives of this mission are:
To perform safe and soft landing on lunar surface.
To demonstrate lunar sample collection and containerization.
To demonstrate ascend from the Moon's surface.
To demonstrate docking and undocking in lunar orbit.
To demonstrate transfer of samples from one module to other.
To demonstrate return and re-entry to Earth for sample delivery.[6]
Spacecraft
The mission will be launched in two phases onboard two LVM3 rockets developed by ISRO. The spacecraft will have five modules packed into two composites which will be launched separately, using two separate LVM3 launch vehicles.[17]
The first launch is planned to carry the ascender module and descender module. The second launch would carry the transfer module, re-entry module, and the propulsion module.[17]
The final spacecraft will get assembled into an integrated module by docking in Earth orbit before proceeding to the Moon.[6][2][18] This will be done via Earth-orbit docking maneuvers.
Propulsion Module is similar to the propulsion module on Chandrayaan-3. It will ferry the combined modular spacecraft to the moon.[19][20][3]
LanderModule will land on the Moon with instrumentation. It supports the ascend stage along with the soil sampling instrumentation. It is designed to last 1 lunar day or 14 earth days on the moon.[19][20][3]
AscenderModule will eject from the lander and would launch from the Moon using the lander as a launch pad after the samples from the Moon are collected and stored. It will then enter low-lunar orbit.[19][20][3]
Transfer Module will collect the samples from the ascend stage, transfer them to the re-entry module, fire its engine to set both itself and the re-entry module towards Earth, release the payload and loop back around the Earth.[19][20][3]
It is planned that after touchdown, a robotic arm, mounted on the Lander Module will scoop about 2-3 kg of samples from around the landing site and transfer them to a container on the Ascent Module . In addition, a drilling mechanism will collect sub-surface samples and transfer them to another container to the Ascent Module.[4]
Apart from the propulsion module, the transfer module is also equipped with an onboard Liquid Apogee Motor (LAM) for return operation maneuvers including the trans-Earth injection. As per earlier reports, the lander module will have six throttleable landing thrusters capable of producing 800 newtons of thrust each, while the ascender module will have two lift off thrusters capable of producing 800 newtons of fixed thrust each.[21] The integrated assembly of all modules after docking in Earth orbit is expected to weigh at least 6,727 kg (14,830 lb).[21]
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