Leonard David's INSIDE OUTER SPACE

Credit: XinhuaVideo/Inside Outer Space screengrab

China’s Mars sample return project will mirror to a large degree the technological prowess the country exhibited in their Chang’e-5 lunar sample return mission.

Chang’e-5 landed on the Moon in December 2020 and rocketed back to Earth 1,731 grams of lunar rocks and soil.

Wu Weiren, chief designer of China’s lunar exploration program and an academician of the Chinese Academy of Engineering, identified the challenges ahead.

Departing ascender imaged by the Chang’e-5 lander.
Credit: CCTV/CNSA/CLEP

Much heavier than lunar probes

According to a China Daily report, first, a landing capsule will touch down on the Martian surface and collect and seal samples. Next, it will lift an ascender to transfer the samples to a spacecraft orbiting Mars, and then the orbiter will release a reentry craft to carry the samples back to Earth.

“The spacecraft for a sample-return mission to the Red Planet will be much heavier than lunar probes as it will carry a greater amount of fuel to fly a very long distance,” Wu said on the sidelines of the fifth session of the 13th National Committee of the Chinese People’s Political Consultative Conference.

China is building upon a heritage of Long March boosters.
Credit: CALT

To carry out a Mars return sample initiative, there’s need for the super-heavy rocket, the Long March-9, for the nation’s prospective crewed lunar programs and other deep-space expeditions.

Lunar exploration

In a related China Daily article, Wu also outlined the next Moon exploration steps: The Chang’e-7 and Chang’e-6 robotic probes.

China plans to send its Chang’e-7 robotic probe to search for water and other resources at the Moon’s south pole.

“The Chang’e-7 mission is set to find traces of ice at the south pole, investigate the environment and weather there, and survey its landforms,” said Wu. “It will also be tasked with detecting the natural resources beneath the south pole’s surface. Moreover, mission planners are considering if we can use the probe to dig into the surface to check the underground structures and compositions.”

In this multi-temporal illumination map of the lunar south pole, Shackleton crater (19 km diameter) is in the center, the south pole is located approximately at 9 o’clock on its rim. The map was created from images from the camera aboard the NASA Lunar Reconnaissance Orbiter.
Credits: NASA/GSFC/Arizona State University

Major considerations

Wu said the selection of the south pole as Chang’e -7’s destination was based on two major considerations.

“The Moon’s south pole is likely to have a favorable solar illumination condition that means sustained power supply and stable temperatures, and those will allow for long-term robotic exploration and manned activities,” Wu said. “By comparison, on other places on the Moon, solar illumination is much shorter, and temperature changes between lunar day and lunar night usually stand at about 300 C.”

A second reason lies in water, Wu said. “The permanently shadowed craters on the south pole may harbor reservoirs of ice and other volatile compounds, and they will be valuable resources for manned explorations.”

Wu said Chinese engineers are developing a special craft able to fly from the landing site to a nearby crater to explore for traces of water.

The lunar far side as imaged by NASA’s Lunar Reconnaissance Orbiter using its LROC Wide Angle Camera.
Credit: NASA/Goddard/Arizona State University

Landing site decision

China’s Chang’e-6 mission, Wu said could land somewhere on the far side of the Moon or a place at the south pole.

The Chang’e-6 probe is a backup to its predecessor, Chang’e 5, so it is capable of collecting and bringing samples back to Earth, reports China Daily.

“If the probe is to conduct sampling tasks on the far side, then we will need to deploy one or two relay satellites in a lunar orbit to transmit signals between Chang’e-6 and ground control,” Wu said. “Similarly, landing it on the south pole and retrieving samples from there will also be challenging. So scientists need time to decide which plan will be adopted.”