What is the actual mass of the sample retrieved by Chang'e 5?

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Wikipedia says:

with an expected return to Earth around 16 December 2020. Chang'e 5 will be China's first sample return mission, aiming to return at least 2 kilograms (4.4 pounds) of lunar soil and rock samples back to the Earth

An article China's moon rocks are officially on their way to Earth as Chang'e 5 probe leaves lunar orbit says:

A container carrying around 4.4 lb. (2 kilograms) of lunar samples sits inside a reentry capsule attached to the orbiter.

Is the mass already known (and if it is, how), or do we have to wait for the container to land?


2 Answers 2


The given value (2kg) is approximate and won't be known exactly until the container is recovered. Knowing the typical composition (including density) of Moon rocks and the volume of the container, one can easily foresee the average mass of the samples, but the actual mass will depend on the local composition, granularity (amount of empty space between grains), precision of the sample acquisition hardware and a couple more minor factors.

Currently better estimates could be achieved by estimating the craft mass basing on thrust and acceleration, but they would still be quite inaccurate.


The sample mass after recovery is 1.731 kg.

NASA Chang'e 5 article:

The sample was recovered and weighed, showing 1.731 kg of lunar regolith was returned.


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