What is the Light?

Explored some more of the wreck today. That sentence is a denial. I'm filling in space here to avoid what has to be said. There's... there's someone else here. There's someone else alive. On the wreck. I've been too preoccupied with my own survival to consider that there could be another. There's someone else here.
How? I'm the only survivor. The wreck's large, I haven't explored all of it and I can only guess from leeward shadows of how much there really is. I've been up and down the larger sections calling out for others but no one's answered. Perhaps they're avoiding me. I can't think of why. It's lonely out here. Maybe they didn't hear me over the solar surf. I doubt it.
My indication my solitude was broken, my footprint in the sand, was simple. I've been marking off rotten bulkheads with tape. I've found rolls of tape throughout the wreck. If only caloris was as plentiful. Anyway, unstable bulkheads are dangerous. Breaking them could lead to more debris, which this place doesn't need, or in the worst case I could end up launched into space. Just out of caution I'd marked some areas near the habitat I'm building, an exercise in vigilance. I've traveled by them every day for the past few weeks. And this morning when I went out to forage some had been moved, several where completely gone. If they'd simply come loose they'd be floating nearby. They had to have been removed. I'm not alone. I don't know what I'm going to do.