The surface is kind of fuzzy, like Earth it starts with a thin atmosphere at the outer boundary of the planet. (Actually HD 189733 b's atmosphere is evaporating

The surface is kind of fuzzy, like Earth it starts with a thin atmosphere at the outer boundary of the planet. (Actually HD 189733 b's atmosphere is evaporating, so you'll encounter a lot of it in a thin fog around the planet as you approach with your 1kg-weight planet bombing vessel.) After dropping the weight, the same thing happens with the weight as if you dropped it from Earth orbit: it speeds up in free fall and will start to heat up quickly as it compresses the gases in front of it, like any space rock falling on a planet. In HD 189733 b's case the atmosphere is crazy hot from the outset, so the steel weight will flicker like a bright light and evaporate very fast. After that the matter of the weight becomes part of the planet's atmosphere. Since iron gas is heavier than the other gases in the atmosphere, it will slowly sink towards the center - but due to wind motion that may take a long time. On its way down, the matter of the steel weight will encounter increasing pressures and temperatures until it reaches a fuzzy transition layer where gases are liquid, and even further down may exist in pseudo-liquid states that are like nothing found on Earth, called metallic hydrogen. At the center of the gas giant, there may be a molten or solid core of rocky elements, where the iron from the steel weight will eventually settle. If you'd try gently dropping a larger object (preferrably into a cooler gas giant), it will survive the heat of atmospheric entry mostly intact, however. After that, it will reach terminal velocity and fall down based purely on its buoyancy. Traversing the atmosphere might take a long time during which the object may encounter many layers of clouds and other cool weather phenomena. As it falls, it too will encounter ever-increasing density and temperature which will eventually result in the dissolution of the object.