- "There! You see that? That's a Marker test lab. They're everywhere at all the major colonies and outposts."
- —Jacob Danik
The Luna Marker was a man made Red Marker located in the New Horizons Lunar Colony of the Earth's moon. By the looks of it, it was approximately as large as the Site 12 Marker, and was covered in a shroud that prevented the Marker Signal from spreading all around it. According to Jacob Danik, the shroud had a laboratory built within it, possibly similar to the one in Titan Station located in the Government Sector.
After Danik captured Isaac, he made Isaac witness as he detonated the shroud and the lab around the Red Marker, exposing it. Then he proceeded to execute Isaac, but Isaac managed to evade his shot and fell into a pile of dead EarthGov soldiers.
While Isaac was blacked out, a Necromorph infestation began ravaging the colony as the Marker Signal leaked everywhere and began turning dead tissue into creatures. It is unknown what happened to the Marker and the colony after Isaac left the moon, but most likely it met a similar fate to the Ishimura, the Sprawl and the Uxor colony or the EarthGov managed to contain the outbreak before the Brother Moons arrived.