placing any block on a asteroid that has not had a block placed on it before ( making it a managed asteroid the ones that show a power and shield meter when targeted)
will lose the asteroids original mass and only have mass equal to the blocks you placed on it.
the mass will return to normal by reloading sector either relogging or traveling about 3 sectors away and back.
1 find wild asteroid take note of its mass
2 place a block of any type on it
the asteroid should lose its mass you can even knock it around with a ship core.