# Lunar Polar Exploration Mission

The Lunar Polar Exploration Mission (LUPEX) (also called as Chandrayaan-5) is a planned joint lunar mission by the Indian Space Research Organisation (ISRO) and Japan Aerospace Exploration Agency (JAXA). The mission would send an uncrewed lunar lander and rover to explore the south pole region of the Moon no earlier than 2028. It is envisaged to explore the permanently shadowed regions and to determine the quantity and quality of water on the Moon. JAXA is likely to provide the H3 launch vehicle and instruments and ISRO would be providing the lander.Both sides will also develop a 250kg lunar rover.
LUPEX will follow the planned lunar sample-return mission Chandrayaan-4.

## History

ISRO signed an Implementation Arrangement (IA) in December 2017 for pre-phase A, phase A study and completed the feasibility report in March 2018 with JAXA to explore the polar regions of Moon for water with a joint Lunar Polar Exploration Mission (LUPEX) that would be launched no earlier than 2028.
ISRO and JAXA held the Joint Mission Definition Review (JMDR) in December 2018. By the end of 2019, JAXA concluded its internal Project Readiness Review.
Since Chandrayaan-2's lander crashed on the Moon during its landing attempt in September 2019, India started to study a new lunar mission named Chandrayaan-3 as a repeat attempt to demonstrate the landing capabilities needed for the LUPEX.
In a joint statement by JAXA and NASA on 24 September 2019, the possibility of NASA joining the LUPEX mission was discussed.
JAXA finished its domestic System Requirement Review (SRR) in early 2021. In April 2023, LUPEX Working Group 1 arrived in India to share information of landing site analysis on promised candidate sites, methods of estimating lander and rover position on moon, information of ground antennas for command and telemetry.
India's Space Commission authorized ISRO to begin work on the LUPEX mission on 7 October 2024. The union cabinet has received the report, and approval is anticipated shortly. which was received on 14th March 2025. As of February 2025, teams are working on hardware design and development after the project was approved and the configuration study concluded. ISRO also started developmental work for a heavier lander engine.

## Overview

The Lunar Polar Exploration mission would demonstrate new surface exploration technologies related to vehicular transport and lunar night survival for sustainable lunar exploration in polar regions. For precision landing it would utilize a feature matching algorithm and navigational equipment derived from JAXA's Smart Lander for Investigating Moon (SLIM) mission. The lander's payload capacity would be 350 kg (770 lb) at minimum. The rover would carry multiple instruments by JAXA and ISRO including a drill to collect sub-surface samples from 1.5 m (4 ft 11 in) depth. Water prospecting and analysis are likely to be mission objectives.
The European Space Agency's Exospheric Mass Spectrometer L-band (EMS-L) of PROSPECT mission was originally planned to fly as a payload on the Russian Luna 27 mission, however EMS-L will now fly on this mission due to continued international collaboration being thrown into doubt by the 2022 Russian invasion of Ukraine and related sanctions on Russia. Payload proposals from other space agencies might be sought.
The lander has been fully re-engineered by ISRO, which required the development of a new engine. The same engine will be used by ISRO in the future for crewed lunar landing missions. The LUPEX mission will test this engine, developed by Liquid Propulsion Systems Centre (LPSC). The rover now weighs 350 kg, while the lander is heavier (in comparison to the original design). The rover is mounted externally since it is heavy and cannot be transported within the lander like it was in Chandrayaan-3. A sky crane like arrangement has now been designed to deploy it on the Moon's surface.
One of the main challenges ahead is choosing a specific landing location, according to Inoue Hiroka, a researcher with the Lunar Polar Exploration Project Team at JAXA's Space Exploration Center. Landing at the south polar zone of the Moon is the plan, as it is thought to have a high probability of having water. There aren't many level places in this area, though, that are perfect for landing and guaranteeing adequate lighting and communication. The team intends to make its landing site public as soon as they determine the ideal place, since other nations may select the same area.

## Payloads

Some selected Japanese instruments along with the candidate instruments of ISRO and ESA and the invited international collaborators by JAXA.
* REsource Investigation Water Analyzer (REIWA): Instrument package of the four instruments.
** Lunar ThermoGravimetric Analyzer (LTGA): Thermogravimetric analyses of the drilled samples for water content.
** TRIple-reflection reflecTrON (TRITON): Identification of chemical species of the volatile component in the drilled samples based on mass spectrometry.
** Aquatic Detector using Optical REsonance (ADORE): Water content measurement in the drilled samples based on cavity ring-down spectrometry.
** ISRO Sample Analysis Package (ISAP): Mineralogical and elemental measurement of the drilled samples. (ISRO)
* Ground Penetrating Radar (GPR): Underground radar observation up to 1.5 meter during rover traverse. (ISRO)
* Permittivity and Thermo-physical Investigation for Moon's Aquatic Scout (PRATHIMA): For in-situ detection and quantification of water-ice mixed with lunar regolith. The payload consists of a multipurpose probe that will be deployed into ~20-30 cm of the lunar surface to scout and quantify the presence of water-ice. (PRL/ISRO)
* Mid-IR spectrometer (MIR): To detect water and OH signature on the surface. (ISRO)
* Advanced Lunar Imaging Spectrometer (ALIS): Near-infrared imaging spectrometer for H $_2$O/OH observation of the surface and drilled regolith.
* Neutron Spectrometer (NS): Underground neutron (hydrogen) observation up to one meter during rover traverse. (NASA)
* Exospheric Mass Spectrometer for LUPEX (EMS-L): Surface gas pressure and chemical species measurement. (ESA)