An astronaut's mass remains the same on the Moon as it is on Earth.

Here's why:

* Mass is the amount of matter in an object. It's a fundamental property and doesn't change based on location.

* Weight, on the other hand, is the force of gravity acting on an object's mass.

The Moon has a much weaker gravitational pull than Earth. This means an astronaut on the Moon would *weigh* less, but their *mass* would stay the same.