Fallout New Vegas: This odd dome-like structure?

So I'm playing one of my favorite games: Fallout 3: New Vegas. As I'm wandering around, I'm noticing a glimpse of what looks like a giant alien space craft, or maybe an observatory of some sort. So I finally decided to see if there's a way to get to the structure, and I've searched I believe all the way around the massive crater it created and found no way in. I know it's not the communications disc on Black Mountain because I've been there, and this is not the structure. The top of this dome can be seen in Primm Pass, in the area where the Blind Deathclaw is just on top of the hill there, and it's pretty close. A lot of places seem to surround it, one of notability is Hidden Valley where :Spoiler Alert: You aid the Brotherhood of Steel to repair their communications, and begin an assortment of quests. Anyway, I'm wondering if anyone has any information on what this could possibly be. I know I have all the add-ons for Fallout 3: New Vegas, or at least the Gun Runners Arsenal, so I'm wondering if it's there for a future DLC release? If not, could someone tell me what it is and how I might explore it? Thanks :)