JAXA–NASA Collaboration on LUPEX Moves Forward - NASA’s Neutron Spectrometer to fly on the LUPEX Rover

The Japan Aerospace Exploration Agency (JAXA) announces that it has signed an Implementing Arrangement (IA) with the National Aeronautics and Space Administration (NASA) regarding cooperation on the Lunar Polar Exploration (LUPEX) mission. Through this agreement, NASA’s Neutron Spectrometer (NS) is planned to be installed on the LUPEX rover, which will explore the Moon’s South Pole region.

LUPEX is an international joint mission with the Indian Space Research Organization (ISRO). Japan will be responsible for the development and operation of the launch vehicle and rover, while India will be responsible for the development and operation of the lander.
The LUPEX rover will carry not only Japanese instruments but also ISRO, NASA, and European Space Agency (ESA)’s instruments.

NS is a neutron spectrometer designed to detect hydrogen — a key indicator of water ice — beneath the lunar surface. By measuring variations in neutron flux from the lunar regolith, the instrument enables high‑resolution detection of potential subsurface water ice deposits.
The LUPEX rover, equipped with NS, will conduct detailed surveys to determine the distribution and quantity of water resources near the surface.

The operation of the LUPEX rover will be supported by NASA’s Deep Space Network (DSN).
The LUPEX rover, which is planned to land in the Moon’s south polar region, will be operated through direct communication with Earth. Because the lunar polar environment cycles through approximately two weeks of continuous visibility followed by two weeks of non‑visibility, support from the DSN is essential to make the most effective use of the limited communication windows available.

In the LUPEX mission, data obtained from NS on the distribution of hydrogen will be analyzed together with a diverse set of measurements acquired by other instruments onboard the rover.
Through this integrated analysis, the mission is expected to provide critical insights into the potential accessibility of water resources in the lunar polar regions, as well as knowledge that will support future human exploration.
The outcomes of LUPEX will not only represent an important milestone in the international exploration efforts jointly advanced by JAXA, ISRO, NASA, and ESA, but will also contribute to future lunar activities, including NASA’s Artemis program.
JAXA will continue working with international partners to advance sustainable utilization of the lunar surface and to open new pathways for the future of lunar exploration.