LUPEX (Lunar Polar Exploration)

JAXA (Japan) and ISRO (India) · Rover · 2028In development

In development, not launched: India's government cleared its share on March 10, 2025 and the two agencies signed the implementing arrangement on August 29, 2025; joint design work is underway (fifth technical interface meeting, December 2025) with launch targeted no earlier than 2028, most-cited 2028-2029 (as of Jul 2026). No landing site fixed yet.

LUPEX, also called Chandrayaan-5, is the mission that inverts the usual Chandrayaan pattern: India, which built the rover for Chandrayaan-3, here builds the lander, while Japan supplies the roughly 350 kg rover, the H3 rocket and the launch. It is designed to reach the lunar south pole, drill up to 1.5 metres into the regolith, and settle the question Chandrayaan-1 first raised from orbit and Chandrayaan-3 sampled from the surface: how much water ice is actually there, in what form, and can it be reached. Most English coverage still calls the joint polar rover 'Chandrayaan-4', a name reassigned in September 2024 to India's all-Indian sample return; the ISRO-JAXA rover is now Chandrayaan-5. Japan had been ready to fly this for years. The pacing item was India's own approval, which finally came in March 2025.

Facts as of July 20, 2026, from the sources listed below.

~350kg

JAXA rover, the heaviest lunar rover ever designed to fly

~6,200kg

total launch mass on Japan's H3-24L

1.5m

auger drill depth for subsurface regolith and ice

2028+

targeted launch, most-cited 2028-2029 (as of Jul 2026)

Targets are the operator's current plan (as of July 20, 2026) and can change.

A quarter-scale model of the LUPEX rover at the JAXA pavilion, Expo 2025 in Osaka; the real rover, about 350 kg, would be the heaviest ever driven on the Moon
A quarter-scale model of the LUPEX rover at the JAXA pavilion, Expo 2025 in Osaka; the real rover, about 350 kg, would be the heaviest ever driven on the Moon. Credit: Artem.G (CC BY 4.0).

Not yet flown. Dates on this page are the operator's current targets, tagged with when they were announced, and can change.

Commonly wrong. Several recurring errors in English coverage. First and biggest, the name: for years the ISRO-JAXA polar rover was called 'Chandrayaan-4', so much older writing and even some current pages use that name, but since September 2024 Chandrayaan-4 is India's all-Indian sample return and this joint rover is Chandrayaan-5/LUPEX. Second, who builds what: reports routinely say ISRO builds the rover (as it did for Chandrayaan-3), but here JAXA provides the rover, built by Mitsubishi Heavy Industries, plus the H3 launch, while ISRO provides the lander. Third, the rover mass: a widely quoted 250 kg traces to a misstatement; the consistent JAXA and ISRO figure is about 350 kg. Fourth, the approval: 'India approved LUPEX in 2025' is true but incomplete, because Japan had already funded and approved its side years earlier and was waiting on India, and the exact Indian date is reported variously as March 10, 13 or 14, 2025 (and it was a government/space-establishment clearance, not always described as a full Union Cabinet item like Chandrayaan-4). Fifth, the launch date: '2026' and '2027' still circulate, but the mission is realistically no earlier than 2028, most often 2028-2029. Finally, treat any single hard cost figure with suspicion: no official total budget for LUPEX has been published.

01Mission facts

Status (as of Jul 2026)In joint design and development; not launched. India's government cleared its part on March 10, 2025; implementing arrangement signed August 29, 2025; fifth technical interface meeting held in Japan December 15 to 17, 2025; an ISRO delegation visited Tanegashima in April 2026
Who builds whatJAXA provides the H3 launch vehicle and the rover (built by Mitsubishi Heavy Industries) plus instruments; ISRO provides the lander and several rover instruments. This inverts Chandrayaan-3, where ISRO built both lander and rover
Mission goalLand near the lunar south pole and determine the quantity and quality of water ice, including in permanently shadowed regions, using a rover that drills to about 1.5 m and analyzes samples in place
Launch vehicleJapan's H3-24L (the H3 in its two-booster, long-fairing configuration), from Tanegashima Space Center; the H3-24L variant was confirmed at the third technical interface meeting in May 2025
RoverAbout 350 kg including instruments, roughly 2.0 x 1.8 x 3.3 m, able to climb 25-degree slopes; built by Mitsubishi Heavy Industries. It carries a 1.5 m earth-auger drill and, after a redesign that found it overweight, drops radioisotope heater units for a passive insulating scheme to survive the lunar night
Lander and new engineISRO develops the lander (about 6,000 kg), which will use a new L9 3.1 kN liquid-fuel engine from the Liquid Propulsion Systems Centre; a prototype L9 was hot-fired in 2025 per ISRO's 2025-26 annual report
International payloadThe rover carries Japanese instruments (LTGA, TRITON, ADORE, ALIS), Indian instruments (ISAP, PRATHIMA, WaSSPeR, MIR), a NASA neutron spectrometer (subsurface hydrogen to about 1 m), and ESA's EMS-L mass spectrometer, originally built for Russia's Luna-27 and redirected after the 2022 invasion of Ukraine
India's approvalIndia's government cleared its participation on March 10, 2025 (some accounts say March 13 or 14), the gating step; Japan had funded and greenlit its side years earlier
Implementing arrangementISRO and JAXA signed the LUPEX/Chandrayaan-5 implementing arrangement during Prime Minister Modi's Tokyo visit on August 29, 2025, formalizing the partnership
Operating lifetimeDesigned to operate at least about 3.5 months on the surface, up to a maximum of about one year; the mission concept is planned to last well over 100 days
Target launchNo earlier than 2028; JAXA and Wikipedia cite 2028-2029, while some Indian summaries say 2027-2028 (as of Jul 2026). No firm date is manifested
CostNo public total-cost figure has been released for LUPEX, unlike the Rs 2,104 crore Chandrayaan-4 approval; India's share was cleared without a published budget line
Landing siteNot fixed as of July 2026: candidate sites in the south polar region, near permanently shadowed regions, were still under discussion at the December 2025 technical interface meeting

02Mission timeline

  1. 2019

    JAXA and ISRO begin joint study of a polar rover mission, then widely referred to as Chandrayaan-4; Japan proceeds toward funding while India's approval stays pending for years

  2. 10 Mar 2025

    India's government clears its participation in LUPEX/Chandrayaan-5, the long-pending gating step (some accounts date it March 13 or 14)

  3. 13 to 14 May 2025

    Third technical interface meeting in India; the H3-24L is confirmed as the launch vehicle and landing-site options are deliberated

  4. 29 Aug 2025

    ISRO and JAXA sign the LUPEX/Chandrayaan-5 implementing arrangement during PM Modi's Tokyo visit

  5. 2025

    ISRO hot-fires a prototype of the lander's new L9 3.1 kN liquid-fuel engine, per its 2025-26 annual report

  6. 15 to 17 Dec 2025

    Fifth technical interface meeting held in Japan: development progress reviews, H3 interface coordination with Mitsubishi Heavy Industries, and lander-rover interface adjustments

  7. Apr 2026

    An ISRO delegation visits Tanegashima Space Center to prepare development activity

  8. Targeted 2028

    Launch on H3-24L from Tanegashima, most-cited window 2028-2029 (as of Jul 2026)

Teal dots: events that physically happened in flight or on the Moon. Grey: announcements, namings, contracts, and targets.

03The mission

LUPEX is the completeness partner to India's Chandrayaan record, and it flips the roles that made Chandrayaan-3 famous. In 2023 ISRO built both the Vikram lander and the little Pragyan rover; in LUPEX, Japan builds the rover and India builds the lander. JAXA also brings the ride: the H3-24L rocket, in its heaviest twin-booster configuration, lifting the roughly 6,200 kg stack from Tanegashima. The rover itself, about 350 kg and built by Mitsubishi Heavy Industries, is the largest lunar rover anyone has ever designed to actually fly, dwarfing Pragyan's 26 kg and even the Apollo lunar roving vehicle. Its job is to carry a 1.5 metre drill and a suite of water-hunting instruments across the polar terrain and into the cold traps at the edge of permanently shadowed regions.

The science question is old and specific. Chandrayaan-1's Moon Mineralogy Mapper found the spectral signature of water and hydroxyl across the lunar surface in 2009; Chandrayaan-3's Vikram measured the polar regolith directly in 2023. What nobody has done is drill into the polar subsurface and measure how much water ice is there, how it is bound, and whether it is concentrated enough to be a resource. LUPEX's rover is built to answer exactly that: an auger pulls samples from up to 1.5 m down, onboard instruments analyze them, a NASA neutron spectrometer sniffs subsurface hydrogen to about a metre, and ESA's mass spectrometer, a hardware refugee originally built for Russia's cancelled Luna-27 and redirected after the 2022 invasion of Ukraine, reads the volatiles that boil off. Japanese, Indian, American and European instruments ride the same deck.

The multipolar cooperation story is the honest headline. This is not a hosted payload or a data-sharing memo; it is a shared spacecraft with divided hardware responsibility and a joint operations plan, exactly the kind of program that is hard to build across borders. It also carries a small piece of history: the mission spent years as 'Chandrayaan-4' in Indian planning, and Japan had already funded and approved its side while India's government deliberated. When ISRO's sample-return mission took the Chandrayaan-4 name in September 2024, the joint rover became Chandrayaan-5, and India's own approval finally landed in March 2025. The implementing arrangement was signed during Prime Minister Modi's Tokyo visit on August 29, 2025.

Hardware is now moving on both sides. ISRO is developing a new lander around the L9, a 3.1 kN liquid-fuel engine from the Liquid Propulsion Systems Centre, and hot-fired a prototype in 2025. JAXA's rover went through a redesign after it came out overweight, dropping its radioisotope heater units in favour of a passive insulating scheme to survive the roughly two-week lunar night. The two agencies have been meeting face to face on a regular cadence: the fifth technical interface meeting ran in Japan from December 15 to 17, 2025, working through H3 launch-vehicle interfaces with Mitsubishi Heavy Industries and the physical fit between lander and rover, and an ISRO delegation visited Tanegashima in April 2026.

The caveats are the schedule and the site. No landing coordinates exist yet; candidate south-polar sites near permanently shadowed regions were still being deliberated at the December 2025 meeting, which is why this entry carries no coordinate pin. The launch target is soft: JAXA and Wikipedia cite 2028-2029, some Indian summaries say 2027-2028, and the realistic reading as of July 2026 is no earlier than 2028. And unlike Chandrayaan-4, no public total-cost figure has been released, so any rupee or yen number circulating for LUPEX should be treated with care. What is firm is the shape of the thing: a Japanese rocket, a Japanese rover, an Indian lander, four space agencies' instruments, and a drill aimed at the Moon's coldest, most valuable ground.

04In pictures

Another angle on the quarter-scale LUPEX rover model at Expo 2025, showing the wheels and the drill area that will bore up to 1.5 metres into polar regolith. Credit: Artem.G (CC BY 4.0).
Looking down on the Moon's south pole: the permanently shadowed cold traps, mapped by NASA from orbital data, are exactly the ground LUPEX is built to drill. Credit: NASA's Scientific Visualization Studio.
An H3 rocket climbs off Tanegashima in February 2025; LUPEX is baselined to fly on the H3-24L, the vehicle's heaviest configuration. Credit: U.S. Air Force.
ISRO's Chandrayaan-3 Vikram lander, shown as a model; the LUPEX lander is India's larger next-generation successor, built around a new L9 engine. Credit: Aliva Sahoo (CC BY 4.0).

Tap a photo to enlarge.

05Sources

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