I recently observed someone being worried about small space debris (e.g. discarded gloves (?), paint chips) hitting them on the ground. (For these cases, the worry is of course unwarranted, since the object would disintegrate into tiny pieces, and eventually dust or gas, leaving no solid impactor). The object must be large, and if not designed to survive, larger still.
It then occurred to me, what would be the smallest possible object to survive a re-entry, alone?
Specifically, you get one object in a circular LEO (eventually; it will re-enter due to weak air resistance). At least part of it must survive the re-entry in a macroscopic form traveling at dangerous speed.
- How small (volume) can you make this object?
- How small (mass) can you make this object?
- In both cases, what is it made of?
EDIT: this article puts the limits much lower than I would have thought:
Bits and pieces of trash constantly fall from the sky, but nearly everything larger than 4 inches (10 cm) survives in some form, likely in smaller fragments.
To salvage this question, let's focus on the danger aspect. The smaller objects reported are probably harmless dust specks by the time they reach the ground, or maybe pebble-sized nodules. So, how big (by mass, by volume) would an object have to begin to injure someone on the ground (culminating in, say, maybe a golf-ball-sized object falling at terminal velocity)?