Lunar Polar Exploration Mission

The Lunar Polar Exploration Mission (LUPEX) 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 2026. It is envisaged to explore the permanently shadowed regions on the Moon. JAXA is likely to provide the H3 launch vehicle and the rover, while ISRO would be providing the lander.

As per Professor Anil Bhardwaj, Director of Physical Research Laboratory (PRL), LUPEX will serve as a precursor to planned lunar sample-return mission Chandrayaan-4.

History
The Indian Space Research Organisation (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 Japan Aerospace Exploration Agency (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 2026.

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 possibilities of joining NASA's lupex mission were 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.

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 at minimum. The rover would carry multiple instruments by JAXA and ISRO including a drill to collect sub-surface samples from 1.5 m 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.

Payloads
Few selected Japanese instruments along with the candidate instruments of ISRO and ESA and the invited international collaborators by JAXA.


 * Ground Penetrating Radar (GPR): Underground radar observation up to 1.5 meter during rover traverse. (ISRO)
 * Neutron Spectrometer (NS): Underground neutron (hydrogen) observation up to one meter during rover traverse. (NASA)
 * Advanced Lunar Imaging Spectrometer (ALIS): /OH observation of the surface and drilled regolith.
 * Exospheric Mass Spectrometer for LUPEX (EMS-L): Surface gas pressure and chemical species measurement. (ESA)
 * REsourceInvestigation 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: Mineralogical and elemental measurement of the drilled samples. (ISRO)

Following are proposed payloads:
 * 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 proposed experiment 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)
 * Alpha Particle Spectrometer (APS): To measure the alpha particles in the decay chain and to understand the volatile transport on the lunar surface along with measurements from LEGRS. (PRL)
 * Low Energy Gamma Ray Spectrometer (LEGRS): For measuring low energy (46.5 keV) gamma ray line to study the volatile transport on the Moon with Cadmium Zinc Telluride (CZT) detectors. (PRL)
 * LUnar Micrometeorite EXperiment (LUMEX): To measure velocity, flux and mass of incoming micrometeorites on moon and derive volatile escape from the lunar surface. (PRL)
 * Lunar Electrostatic Dust EXperiment (LEDEX): To detect presence of charged dust particles and confirm the dust levitation process in volatile-rich polar region. (PRL)