Chandrayaan-4

Chandrayaan-4 (ⓘ; from Sanskrit: Chandra, "Moon" and yāna, "craat, vehicle") is an upcoming lunar sample return mission of ISRO underdevelopment now and the fourth iteration in its Chandrayaan programme. As of January 2025, the conceptualisation phase has been completed, and the design phase is nearing completion. The mission is expected to launch around 2028. It is planned to return up to 3 kg (6.6 lb) of lunar regolith.

History

Conceptual Phase

The plan for a lunar sample return mission was revealed by the director of the Space Application Centre (SAC), Nilesh M Desai on 17 November, 2023 during the 62nd foundation ceremony of the Indian Institute of Tropical Meteorology (IITM) in Pune. This was confirmed by S. Somanath, the then chairman of ISRO, during the National Space Science Symposium held in Goa on 26 February 2024. 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. 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. 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.

On 20 August 2024, S. Somanath announced that the Indian Space Research Organisation (ISRO) had completed the design of both Chandrayaan-4 and LUPEX, and is now requesting approval from the government.

On 13 February 2025, the Minister of Science and Technology, Jitendra Singh Rana, stated in the Rajya Sabha that Chandrayaan-4 will be a foundational mission that will validate key technologies needed for a crewed lunar landing in 2040. As of February 2025, ISRO is developing a number of subsystems, such as robotic arms for sample collection, specialized payloads, and a high-capacity propulsion system. ISRO organised a research meet in April 2025 to deliberate on the scientific research that can be conducted with the lunar regolith within India.

Cabinet approval

On 18 September 2024, Chandrayaan-4 received approval from the Union Cabinet, chaired by Prime Minister Narendra Modi for ₹2,104.06 crore (US$250 million) and is expected to be completed within 36 months. 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-sealed container, and return them to Earth. The mission will also see docking and undocking — two spacecraft aligning and coming together in orbit.

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:

1. To perform a safe and soft landing on the lunar surface.
2. To demonstrate lunar sample collection and containerization.
3. To demonstrate ascent from the Moon's surface.
4. To demonstrate docking and undocking in lunar orbit.
5. To demonstrate the transfer of samples from one module to another.
6. To demonstrate return and re-entry to Earth for sample delivery.

Spacecraft

The mission will be launched in two phases onboard two LVM3 rockets developed by ISRO. The spacecraft will include five modules packed into two composites, which will be launched separately, using two separate LVM 3 launch vehicles. As an Individual LVM3 rocket has a payload capacity of only 8,000 kilograms,exceeding the combined fuel mass and size of the spacecraft. Hence the flight was optimised for a dual-launch strategy. The spacecraft elements include:

• Propulsion Module is similar to the propulsion module on Chandrayaan-3. It will ferry the combined modular spacecraft to the moon.
• Lander Module will land on the Moon with instrumentation. It supports the ascent stage along with the soil sampling instrumentation. It is designed to last 1 lunar day or 14 Earth days on the moon.
• Ascender Module will eject from the lander and 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.
• Transfer Module will collect the samples from the ascent 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.
• Re-entry Module will hold the sample from lunar orbit. It is designed to survive atmospheric re-entry and land with the lunar regoliths.

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 propulsion module.The final spacecraft will be assembled into an integrated module by docking in Earth orbit before proceeding to the Moon. This will be done via Earth-orbit docking maneuvers. Once they reach lunar orbit, the lander/ascender stack will descent to the lunar surface. 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 in the Ascent Module. The Ascent module would lift-off just prior to the end of a lunar day for a lunar orbit rendezvous with the Transfer module, which will transfer the payload to a Re-entry module before departing from the moon and landing on earth.

Apart from the propulsion module, the transfer module is also equipped with an onboard Liquid Apogee Motor (LAM) for return operation manoeuvres, 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. The integrated assembly of all modules after docking in Earth orbit is expected to weigh at least 9,200 kg (20,300 lb).

Landing site

The landing site was initially planned near to Station Shiv Shakti, the landing site of Chandrayaan-3 which is located between the Manzinus P and Boguslawsky M lunar craters near to the south pole region. ISRO had conducted comprehensive study of this landing site region regarding morphology, hydration and gravity anomalies using data obtained from payloads of Chandrayaan-2 orbiter, Lunar Reconnaissance Orbiter (LRO), Lunar Prospector and GRAIL.

It was proposed in 2026 to land the spacecraft in the Mountainous plains near Mons Mouton of the moon, based on data from the OHRC instrument on the Chandrayaan-2 orbiter and SIS datasets, located even closer to the lunar south pole.Five sites were evaluated of which four were selected, after it was discovered that one of them was in a shadowed region,impeding solar power generation. Of the other given sites, MM4 was suggested as the landing site. Researchers from IIT Kharagpur and PRL surveyed the sites for iron and titanium-rich rocks known as ilmenite-bearing cumulates (IBC), about 4.3-4.4 billion years old that may have preserved records of the moon's early history. There is also potential for samples to have lunar water content within them.

Factors affecting landing site selection include

• Slope less than or up to 10 degrees
• Boulders less than 0.32 meter
• Low Crater and boulder distribution in local topography
• Sunlit for at least 11-12 days.
• Local terrain features don’t shadow the site for long
• Distribution of safe grid of 24m x 24m inside 1km x 1 km landing area

See also

• Chandrayaan programme
• List of missions to the Moon
• Lunar Polar Exploration Mission

Similar missions

• Chang'e 5
• Chang'e 6
• Luna 16
• Luna 20
• Luna 24