# How orbital debris' density affects damage, everything else being equal?

If considering one gram of steel and one gram of foam, which one is the biggest threat and would cause most or least damage to the orbital structure it hits?

Radii of these debris is the only thing that will differ, yet depending on impact velocity, damage should differ too.

How does relation between relative impact velocity and damage caused by impact evolve for the gram of steel and the gram of foam, since there is a wide range of possible impact velocities?

(for instance at 15 km/s (prograde vs retrograde LEO frontal impact) the foam should punch a bigger hole in a solar panel or a hull.

At 0.1 km/s the steel may produce a small bump on a hull while the foam may do nothing).

• Interesting question. I presumeit will depend on the material of the thing it hits too and its size, e.g. is that several meters across/several cm thick. That said my suspicion is that space agency led tests won't have done as detailed a characterisation as the question needs yet, i.e. it could be ahead of the research. Well worth asking here though, someone might have some ideas. Sep 5, 2022 at 20:28
• I expect this to vary widely with the type of material being hit. Compare a piece of glass developing cracks, shattering into pieces and some kind of metal that just gets punched through. Sep 6, 2022 at 8:46
• Kinetic energy is 0.5mv^2. The energy with which a object hits another object is dependent only on the mass & velocity of the object. If the foam & steel have the same velocity that hit with the same energy, the difference will be the area of contact & that the area of damage.
– Fred
Sep 6, 2022 at 13:58