China is set to launch its Chang’e-7 unmanned, robotic space mission, possibly as early as Monday morning, to look for ice water in the permanently shadowed craters of the moon’s south pole.

This marks China’s seventh and most ambitious moon mission so far. Here is what we know about it.

What do we know about Chang’e-7?

The Chang’e‑7 launch window runs from Monday, August 24 to Monday, August 31, according to launch observers. That means the mission could lift off on any day in that period.

The Chang’e-7 comprises an orbiter, a lander, a rover and a hopper.

• The orbiter is the main spacecraft which will remain in the moon’s orbit, mapping the surface and taking images while the mission is under way. It will also relay data and communications between the other Chang’e‑7 components and Earth.
• The lander is the vessel that will touch down on the lunar surface, loaded with the necessary scientific instruments for lunar exploration, near the edge of the Shackleton Crater, a 21km-wide (13-mile-wide) pit close to the moon’s south pole. Lunar missions before this have never come this close to the pole.
• The rover is a small robotic vehicle which can drive around the landing site and which carries equipment to analyse the local environment, including rocks and soil.
• The hopper is a small robotic craft powered by solar energy, designed to “hop” – or fly – short distances from the surface of the moon and land again. It will be used to explore the Shackleton Crater.

How do we know there is water on the moon?

Over the past two decades, several space missions have established that there is water on the moon.

Since the 1960s, even before the first Apollo landing in 1969, scientists speculated that water could exist on the moon. However, when Apollo crews returned samples for testing in the late 1960s and early 1970s, they appeared to be dry.

Finally, in 2009, NASA deliberately crashed a rocket segment and its probe into a shadowed lunar crater to analyse the dust plume it kicked up. This provided one of the clearest direct confirmations that significant ice water does exist on the moon, building on earlier detections of water and hydrogen by probes.

In October 2020, NASA scientists announced that water on the moon is more widespread than previously known. They said water molecules had been found to be encapsulated within mineral grains on the lunar surface and speculated that more water is hidden in ice patches which are in permanent shadows.

NASA describes these permanent shadows as dark areas inside deep craters near the north and south poles of the moon where sunlight has not reached for millions or even billions of years. In 2018, prior to confirming it in 2020, NASA had detected water ice in shadowed parts of the moon through mapping.

Why is it important to find out more about the water on the moon?

Expanding knowledge about water on the moon is vital because ancient polar ice may have preserved a record of lunar volcanic activity and of water delivered by comets and asteroids to the Earth-moon system, offering clues to how our own oceans originally formed.

Additionally, if there is enough water on the moon that is realistically accessible, it could serve as a source of drinking water for crewed lunar missions, and could also help to keep equipment cool.

Hydrogen could also be extracted from moon water to provide fuel, while oxygen could be extracted to breathe, supporting onward missions to Mars or lunar mining.

Could anyone ‘own’ the water on the moon?

The 1967 United Nations Outer Space Treaty bans any nation from claiming sovereignty over the moon or owning it as territory. It does not explicitly prohibit commercial operations, but it requires private activities in space to be authorised and supervised by states and leaves key questions about resource ownership unresolved.

Which recent space missions have searched for frozen water on the moon?

In 2023, Russia’s lunar spacecraft, Luna-25, was launched to look for frozen water in the moon’s south pole. However, the Luna-25 spun out of control and crashed. The crash prevented any scientific data collection or water discovery.

Racing against the Luna-25 mission was India’s Chandrayaan-3, which also aimed to expand knowledge of lunar water ice. Chandrayaan-3 successfully landed in August 2023 and found critical new evidence of water on the surface of the moon’s south pole through soil temperature readings.

Why is exploring the moon’s south pole a challenge?

Attempted landings at the moon’s south pole have failed before because of its challenging terrain, which is full of craters and deep trenches.

The south pole is far from the equatorial region targeted by previous missions, including the crewed Apollo landings.

What is different about the Chang’e-7 mission?

The upcoming Chang’e-7 is aiming to expand knowledge about where, exactly, water is located in the craters of the moon, how deep it is, what form it is in and whether it is indeed possible to access it.

The Chang’e-7’s six-legged hopper has been designed to jump into and out of the deep, shadowed craters near the south pole that are hard for traditional rovers to reach, to look for water ice and other resources.

No previous space mission has used a dedicated hopper to jump in and out of lunar craters in this way.