While it's well-known that Arthur C. Clarke developed the idea of geostationary satellites, it seems far less known that another SciFi author, Jerry Pournelle, developed the idea of kinetic orbital bombardment with metal rods (during his side career as engineer at Boeing):
Project Thor is an idea for a weapons system that launches kinetic projectiles from Earth's orbit to damage targets on the ground. Jerry Pournelle originated the concept while working in operations research at Boeing in the 1950s before becoming a science-fiction writer.
It would make sense if Pournelle (being a SciFi writer) would be the first to use the idea in a SciFi work. But was that really the case?
Wikipedia doesn't seem to offer much clarity (nor certainness) - while all the examples it lists which predate Pournelle's don't fit ("The Moon Is a Harsh Mistress bombardment is Moon based, not from orbit; Lensman series used planetary sized masses instead of small objects). As a matter of fact, Pournelle's own "Footfall" seems to not quite fit the bill, since from what I recall, Fithp don't use artificial objects but instead, meteors.
The first example I saw on Wikipedia that fit 100% and was dated was from 1988:
A smaller "crowbar" variant is mentioned in David's Sling by Marc Stiegler (Baen, 1988)
Question: What was the first instance of SciFi work using the actual Pournelle system? (Specific specs: artificial objects - preferable metal rods - used or deployed as orbital kinetic weapons from Earth Orbit)