# Lunar Polar Exploration Mission
The Lunar Polar Exploration Mission (LUPEX) is a joint robotic mission of the Indian Space Research Organisation (ISRO) and the Japan Aerospace Exploration Agency (JAXA) to prospect for water ice and other volatiles near a permanently shadowed region at the lunar south pole; in India it is designated Chandrayaan-5, the fifth mission in the Chandrayaan series.[1](https://www.isro.gov.in/ISRO_EN/ISRO_JAXA_CH5_Technical_Interface_Meet.html) Japan provides the H3-24L launch vehicle and the rover, built by [Mitsubishi Heavy Industries](https://www.edgepedia.org/mitsubishi-heavy-industries) (MHI), while India provides the lander; launch is targeted no earlier than 2028, with India's Department of Space reporting a September 2028 aim.[1](https://www.isro.gov.in/ISRO_EN/ISRO_JAXA_CH5_Technical_Interface_Meet.html) • [2](https://www.exploration.jaxa.jp/e/program/lunarpolar/) • [3](https://www.news9live.com/science/isro-to-launch-chandrayaan-5-lupex-in-september-2028-2949220)
| Key fact | Detail |
|---|---|
| Mission | Joint ISRO–JAXA lunar south pole volatile survey; designated Chandrayaan-5 in India[1](https://www.isro.gov.in/ISRO_EN/ISRO_JAXA_CH5_Technical_Interface_Meet.html) |
| Launch | No earlier than 2028 (September 2028 per India's Department of Space) on JAXA's H3-24L from Tanegashima[2](https://www.exploration.jaxa.jp/e/program/lunarpolar/) • [3](https://www.news9live.com/science/isro-to-launch-chandrayaan-5-lupex-in-september-2028-2949220) • [4](https://humans-in-space.jaxa.jp/en/biz-lab/tech/lupex/) |
| Division of work | ISRO: lander and payload operations; JAXA: rover, instruments, launch vehicle[4](https://humans-in-space.jaxa.jp/en/biz-lab/tech/lupex/) |
| Masses | Launch mass about 6.5 t; payload-mass figure in the JAXA leaflet that conflicts with the stated launch mass; rover mass reported as 350 kg or 420 kg including instruments[4](https://humans-in-space.jaxa.jp/en/biz-lab/tech/lupex/) • [5](https://www.exploration.jaxa.jp/assets/img/program/Leaflet_LUPEX-e_A4.pdf) |
| Duration | 3.5 months after landing, extendable to one year[4](https://humans-in-space.jaxa.jp/en/biz-lab/tech/lupex/) • [6](https://www.mext.go.jp/content/20240424-mxt_uchukai01-000035587_1.pdf) |
| Excavation | Rover drills regolith to about 1.5 m; WaSSPeR radar maps to 3 m depth at 10 cm vertical resolution[7](https://www.hou.usra.edu/meetings/lpsc2026/pdf/1377.pdf) |
| Science target | Quantity, vertical distribution, and form of lunar water, including mixing with dry regolith, in permanently shadowed regions where temperatures run 20–120 K[2](https://www.exploration.jaxa.jp/e/program/lunarpolar/) • [8](https://www.pnas.org/doi/10.1073/pnas.2321071121) |
## Background and partnership
The partnership grew from a Memorandum of Understanding signed by JAXA and ISRO in November 2016, followed by an Implementation Arrangement on 6 December 2017 for a joint feasibility study of a lunar polar exploration mission.[9](https://global.jaxa.jp/press/2017/12/20171206_isro.html) A 2017 protocol originally envisaged an Indian-built lander and Japanese-built rover launching by 2026; JAXA completed its preliminary feasibility study in 2021, and in April 2023 a joint delegation began studying landing sites using Chandrayaan-3 data.[10](https://www.spacevoyaging.com/news/2023/09/07/lupex-soon-a-new-lunar-mission-from-india-and-japan/)
**Responsibilities are split cleanly.** Japan develops and operates the launch vehicle and the rover; India develops and operates the lander, which carries the rover to the surface.[4](https://humans-in-space.jaxa.jp/en/biz-lab/tech/lupex/) • [11](https://iafastro.directory/iac/archive/browse/IAC-22/A3/2A/68481/) The rover and lander are integrated and launched together on the H3.[11](https://iafastro.directory/iac/archive/browse/IAC-22/A3/2A/68481/) Instruments come from ISRO, JAXA, ESA, and NASA, all aimed at in-situ analysis of polar volatiles.[1](https://www.isro.gov.in/ISRO_EN/ISRO_JAXA_CH5_Technical_Interface_Meet.html)
Key formal steps were taken in 2025. The [Government of India](https://www.edgepedia.org/government-of-india) granted financial sanction for Chandrayaan-5/LUPEX on March 10, 2025.[1](https://www.isro.gov.in/ISRO_EN/ISRO_JAXA_CH5_Technical_Interface_Meet.html) A three-day technical interchange meeting held March 24–26 at the UR Rao Satellite Centre in Bengaluru culminated in a successful Joint Preliminary Design Review.[12](https://www.news9live.com/science/isro-jaxa-conduct-prelimnary-design-review-of-chandrayaan-5-lupex-mission-2950630) In August 2025, on the sidelines of Prime Minister Modi's visit to Tokyo, ISRO and JAXA signed the formal arrangement concerning the mission.[13](https://timesofindia.indiatimes.com/india/during-modis-visit-india-and-japan-ink-pact-for-chandrayaan-5-mission-to-explore-water-on-lunar-south-pole/articleshow/123592271.cms)
## Scientific objectives
The lunar south pole is targeted because permanently shadowed regions (PSRs), areas that never receive direct sunlight, hold temperatures of about 20 K to 120 K, low enough that minimal sublimation occurs even over billions of years.[8](https://www.pnas.org/doi/10.1073/pnas.2321071121) Water ice in these cold traps holds clues to the origin and evolution of lunar volatiles and could serve as feedstock for in-situ resource utilization (ISRU) and surface life-support systems.[14](https://www.frontiersin.org/journals/astronomy-and-space-sciences/articles/10.3389/fspas.2026.1764826/full) The evidence for polar ice is direct but incomplete: in 2009 the [LCROSS](https://www.edgepedia.org/lcross) impactor struck the PSR of Cabeus crater and detected water vapor and other volatiles in the ejecta, yet significant uncertainty remains in characterizing lunar water.[15](https://link.springer.com/article/10.1007/s44461-025-00005-4)
LUPEX's stated goals are to investigate the quantity of lunar water, its distribution on the surface and below ground, and its form, such as the level of mixing with dry regolith.[2](https://www.exploration.jaxa.jp/e/program/lunarpolar/) JAXA frames the mission as also assessing the lunar polar region's suitability for a sustainable base and demonstrating surface exploration technologies including vehicular transport and overnight survival.[16](https://theprint.in/india/isros-next-moon-mission-in-collaboration-with-japanese-space-agency-gathers-steam/1725217/) The rover's demonstrations of roving, overnight survival, and excavation are explicitly intended to feed the development of JAXA's Crewed Pressurized Rover.[5](https://www.exploration.jaxa.jp/assets/img/program/Leaflet_LUPEX-e_A4.pdf)
## Spacecraft and instruments
The mission stack has a launch mass of about 6.5 tonnes.[4](https://humans-in-space.jaxa.jp/en/biz-lab/tech/lupex/) The JAXA leaflet lists a payload-mass figure that conflicts with the stated launch mass of about 6.5 tonnes, and a rover mass of 420 kg including observation instruments, while JAXA's mission pages and Japan's MEXT document list 350 kg for the rover including instruments; the discrepancy is unresolved in official material.[5](https://www.exploration.jaxa.jp/assets/img/program/Leaflet_LUPEX-e_A4.pdf) • [4](https://humans-in-space.jaxa.jp/en/biz-lab/tech/lupex/) • [6](https://www.mext.go.jp/content/20240424-mxt_uchukai01-000035587_1.pdf) The rover measures 2.0 m × 1.8 m × 3.3 m.[4](https://humans-in-space.jaxa.jp/en/biz-lab/tech/lupex/)
**The instrument suite** combines remote survey tools with close-up analyzers. JAXA contributes the REIWA package, whose Lunar Thermal Gravity Analyzer (LTGA) heats 6–10 g regolith samples from 100 to 500 K in 30 minutes to evaporate volatiles and weighs them to a resolution equivalent to a 0.1% weight change for a 6 g sample, and the TRITON mass spectrometer, which identifies volatile species up to mass number 200 at mass resolution up to 150.[7](https://www.hou.usra.edu/meetings/lpsc2026/pdf/1377.pdf) JAXA's ALIS camera builds on the Multi-Band Camera flown on SLIM.[17](https://www.hou.usra.edu/meetings/lpsc2024/pdf/1761.pdf) ISRO contributes the WaSSPeR ground-penetrating radar, operating across a 1.5 GHz bandwidth from 0.5 to 2 GHz to map subsurface permittivity to 3 m depth at 10 cm vertical resolution, plus the Mid-Infrared Spectrometer (MIR) and PRATHIMA, which is designed for in-situ detection and quantification of water ice mixed with surface and subsurface soil.[7](https://www.hou.usra.edu/meetings/lpsc2026/pdf/1377.pdf) • [16](https://theprint.in/india/isros-next-moon-mission-in-collaboration-with-japanese-space-agency-gathers-steam/1725217/) NASA's Neutron Spectrometer detects hydrogen, a key indicator of water ice, beneath the surface by measuring variations in neutron flux from the regolith; JAXA signed an Implementing Arrangement with NASA for its inclusion.[18](https://humans-in-space.jaxa.jp/en/biz-lab/news/detail/005577.html) ESA's EMS-L measures surface gas pressure and chemical species, and ALIS and MIR carry light sources to investigate shadowed regions.[7](https://www.hou.usra.edu/meetings/lpsc2026/pdf/1377.pdf)
**Operations proceed in two steps.** The rover first performs a coarse survey with remote-sensing instruments to select drilling sites, then conducts fine analysis: it drills regolith to about 1.5 m, collects samples, and hands them to the REIWA instruments for closed-system quantitative analysis.[7](https://www.hou.usra.edu/meetings/lpsc2026/pdf/1377.pdf) • [4](https://humans-in-space.jaxa.jp/en/biz-lab/tech/lupex/) The MEXT document highlights this closed-system approach with active heating to 500 K and 0.1 wt% precision as an improvement over prior missions' open-system or indirect water measurements.[6](https://www.mext.go.jp/content/20240424-mxt_uchukai01-000035587_1.pdf) The rover is designed to travel set distances and climb slopes up to 25 degrees, with battery charging planned once before and once after sample collection.[19](https://indianexpress.com/article/india/chandrayaan-5-mission-india-japan-design-phase-10007428/)
Communications shape the rhythm of the mission: the lunar polar environment cycles through roughly two weeks of continuous Earth visibility followed by two weeks of non-visibility, so rover operations depend on support from NASA's Deep Space Network.[18](https://humans-in-space.jaxa.jp/en/biz-lab/news/detail/005577.html)
## How it compares with other lunar missions
Against Chandrayaan-3, LUPEX is a step change in ambition. Chandrayaan-3's lander had a mission life of one lunar day, 14 Earth days, and a mass of 1,749.86 kg including its 26 kg rover, and it landed at 69.367621 S, 32.348126 E, a mid-latitude site well away from the pole.[20](https://www.isro.gov.in/media_isro/pdf/Missions/LVM3/LVM3M4_Chandrayaan3_brochure.pdf) LUPEX targets a precision landing in the highlands around the lunar south pole, carries a heavier lander with a flip-out ramp to lower the rover, and plans a 3.5-month rover campaign with drilling rather than a two-week surface stay.[3](https://www.news9live.com/science/isro-to-launch-chandrayaan-5-lupex-in-september-2028-2949220) • [4](https://humans-in-space.jaxa.jp/en/biz-lab/tech/lupex/)
The closest analog in intent was NASA's VIPER rover, a 450 kg ice prospector with three spectrometers and a 1 m drill, planned for a 100-Earth-day mission in the Nobile region of the south pole, delivered by Astrobotic's Griffin lander; the NASA mission page listed launch as late 2024 before the mission's later cancellation.[21](https://science.nasa.gov/mission/viper/in-depth/) VIPER's TRIDENT drill sampled to 1 m depth in 10 cm bites, shallower than LUPEX's 1.5 m target.[22](https://ntrs.nasa.gov/api/citations/20220005327/downloads/VIPER-SRR-June2022-Ennico.pdf?attachment=true) • [7](https://www.hou.usra.edu/meetings/lpsc2026/pdf/1377.pdf) The neutron spectrometer flying on LUPEX belongs to the same NASA instrument family as the NSS flown on VIPER and on the Carnegie Mellon MoonRanger micro rover.[23](https://www.nasa.gov/solar-system/moon/nasas-water-hunting-tool-will-help-scout-moons-south-pole/)
## Recent developments
The schedule has slipped substantially. The mission was originally planned for launch in 2025; India's Department of Space told a Parliamentary Standing Committee that ISRO and JAXA are now targeting September 2028, and JAXA's official pages state no earlier than 2028.[3](https://www.news9live.com/science/isro-to-launch-chandrayaan-5-lupex-in-september-2028-2949220) • [2](https://www.exploration.jaxa.jp/e/program/lunarpolar/) The designation also changed: the mission was once designated [Chandrayaan-4](https://www.edgepedia.org/chandrayaan-4) before ISRO assigned that name to an independent sample-return mission.[3](https://www.news9live.com/science/isro-to-launch-chandrayaan-5-lupex-in-september-2028-2949220)
By 2025 the design work had matured. JAXA Project Manager Asoh Dai stated that instrument selections were complete, engineering model testing nearly done, and the partners entering the preliminary design phase.[19](https://indianexpress.com/article/india/chandrayaan-5-mission-india-japan-design-phase-10007428/) The Joint Preliminary Design Review followed in March 2025, the Indian financial sanction came on March 10, 2025, and the formal bilateral arrangement was signed in August 2025.[12](https://www.news9live.com/science/isro-jaxa-conduct-prelimnary-design-review-of-chandrayaan-5-lupex-mission-2950630) • [1](https://www.isro.gov.in/ISRO_EN/ISRO_JAXA_CH5_Technical_Interface_Meet.html) • [13](https://timesofindia.indiatimes.com/india/during-modis-visit-india-and-japan-ink-pact-for-chandrayaan-5-mission-to-explore-water-on-lunar-south-pole/articleshow/123592271.cms) NASA's participation was formalized through the Neutron Spectrometer Implementing Arrangement.[18](https://humans-in-space.jaxa.jp/en/biz-lab/news/detail/005577.html)
## Challenges and significance
Several technical hurdles remain. Landing site choice is constrained: even within the south polar region where water is expected, only a limited number of safe landing sites exist, and selection must balance secured sunlight for rover energy, line-of-sight communication with Earth, safe landing and traverse inclination, and the temperature and geology of scientific interest.[5](https://www.exploration.jaxa.jp/assets/img/program/Leaflet_LUPEX-e_A4.pdf) The launch vehicle carries its own history: the H3 failed its maiden launch on March 7, 2023 due to a second-stage misfire, with at least 14 further launches scheduled before the LUPEX flight.[10](https://www.spacevoyaging.com/news/2023/09/07/lupex-soon-a-new-lunar-mission-from-india-and-japan/) On night survival, official JAXA material lists "overnight resistance" as a technology to be demonstrated without a duration figure, while one press report states the lander is designed to survive the lunar night for an estimated six terrestrial months, unlike Chandrayaan-3; the engineering approach and the figure remain unconfirmed in official sources.[5](https://www.exploration.jaxa.jp/assets/img/program/Leaflet_LUPEX-e_A4.pdf) • [10](https://www.spacevoyaging.com/news/2023/09/07/lupex-soon-a-new-lunar-mission-from-india-and-japan/)
The mission's significance lies in what it would prove. A multi-month polar rover that drills to 1.5 m, quantifies water at 0.1 wt% precision in a closed system, and survives the night would demonstrate, in one flight, the mobility, excavation, and survival technologies that both ISRU concepts and JAXA's Crewed Pressurized Rover depend on.[5](https://www.exploration.jaxa.jp/assets/img/program/Leaflet_LUPEX-e_A4.pdf) • [6](https://www.mext.go.jp/content/20240424-mxt_uchukai01-000035587_1.pdf)
## References
1. [ISRO and JAXA Gear Up for Joint Chandrayaan-5 / LUPEX Mission in the Technical Interface Meet, ISRO](https://www.isro.gov.in/ISRO_EN/ISRO_JAXA_CH5_Technical_Interface_Meet.html)
2. [Lunar Polar Exploration Mission, JAXA Space Exploration Center](https://www.exploration.jaxa.jp/e/program/lunarpolar/)
3. [ISRO to launch Chandrayaan 5/LUPEX in September 2028, News9live](https://www.news9live.com/science/isro-to-launch-chandrayaan-5-lupex-in-september-2028-2949220)
4. [Lunar Polar Exploration (LUPEX), JAXA Human Spaceflight Technology Directorate](https://humans-in-space.jaxa.jp/en/biz-lab/tech/lupex/)
5. [LUPEX official leaflet, JAXA](https://www.exploration.jaxa.jp/assets/img/program/Leaflet_LUPEX-e_A4.pdf)
6. [月極域探査機（LUPEX）について, Japan MEXT](https://www.mext.go.jp/content/20240424-mxt_uchukai01-000035587_1.pdf)
7. [In-Situ Volatile Characterization at the Lunar South Polar Region: Science Objectives, Instruments, and Status of the Lunar Polar Exploration Mission, LPSC 2026 abstract](https://www.hou.usra.edu/meetings/lpsc2026/pdf/1377.pdf)
8. [Exploring, sampling, and interpreting lunar volatiles in polar cold traps, PNAS](https://www.pnas.org/doi/10.1073/pnas.2321071121)
9. [JAXA Signs Implementation Arrangement (IA) with ISRO concerning joint study of Joint Lunar Polar Exploration, JAXA](https://global.jaxa.jp/press/2017/12/20171206_isro.html)
10. [LUPEX: Soon a new lunar mission from India and Japan, Space Voyaging](https://www.spacevoyaging.com/news/2023/09/07/lupex-soon-a-new-lunar-mission-from-india-and-japan/)
11. [IAC-22/A3/2A/8, LUPEX joint exploration paper, IAC Archive](https://iafastro.directory/iac/archive/browse/IAC-22/A3/2A/68481/)
12. [ISRO, JAXA conduct Preliminary Design Review of Chandrayaan 5/LUPEX mission, News9live](https://www.news9live.com/science/isro-jaxa-conduct-prelimnary-design-review-of-chandrayaan-5-lupex-mission-2950630)
13. [During Modi's visit, India and Japan ink pact for Chandrayaan-5 mission, Times of India](https://timesofindia.indiatimes.com/india/during-modis-visit-india-and-japan-ink-pact-for-chandrayaan-5-mission-to-explore-water-on-lunar-south-pole/articleshow/123592271.cms)
14. [High-resolution accessibility and energy cost assessment of 31 priority permanently shadowed regions at the lunar south pole, Frontiers in Astronomy and Space Sciences](https://www.frontiersin.org/journals/astronomy-and-space-sciences/articles/10.3389/fspas.2026.1764826/full)
15. [A review of lunar water extraction technologies, Springer](https://link.springer.com/article/10.1007/s44461-025-00005-4)
16. [ISRO's next Moon mission in collaboration with Japanese space agency gathers steam, ThePrint/PTI](https://theprint.in/india/isros-next-moon-mission-in-collaboration-with-japanese-space-agency-gathers-steam/1725217/)
17. [JAXA's Mission Instruments in the ISRO-JAXA Joint Lunar Polar Exploration (LUPEX) Project, LPSC 2024 abstract](https://www.hou.usra.edu/meetings/lpsc2024/pdf/1761.pdf)
18. [JAXA–NASA Collaboration on LUPEX Moves Forward, JAXA](https://humans-in-space.jaxa.jp/en/biz-lab/news/detail/005577.html)
19. [Chandrayaan-5 mission: India, Japan to enter design phase, The Indian Express](https://indianexpress.com/article/india/chandrayaan-5-mission-india-japan-design-phase-10007428/)
20. [LVM3-M4/Chandrayaan-3 Mission Brochure, ISRO](https://www.isro.gov.in/media_isro/pdf/Missions/LVM3/LVM3M4_Chandrayaan3_brochure.pdf)
21. [VIPER In Depth, NASA Science](https://science.nasa.gov/mission/viper/in-depth/)
22. [VIPER System Requirements Review, NASA NTRS](https://ntrs.nasa.gov/api/citations/20220005327/downloads/VIPER-SRR-June2022-Ennico.pdf?attachment=true)
23. [NASA's Water-Hunting Tool Will Help Scout Moon's South Pole, NASA](https://www.nasa.gov/solar-system/moon/nasas-water-hunting-tool-will-help-scout-moons-south-pole/)
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*Topic: Encyclopedia › Technology and the built world › Transport and spaceflight › Spaceflight › Spacecraft and mission dynamics › Space probes and planetary science missions › Lunar robotic missions*
*Initially written Sep 17, 2026 · Reviewed: Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026*
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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license