The astronaut's mass doesn't change. It's the same wherever he goes,
because it doesn't depend on what else is around him.
His weight depends on what else is near him, so it changes, depending
on where he is.
Weight = (mass) x (gravity)
On Earth, Weight = (145 kg) x (9.81 m/s²) = 1,422.5 newtons.
(about 320 pounds)
On the moon, Weight = (145 kg) x (1.62 m/s²) = 234.9 newtons.
(about 53 pounds)