I transcribed the mission briefing scene for reference:
Mission Briefer: This is Spartan [Cal?]-141 who will be the ranking officer on this mission. I realize that is highly unusual and you have strong feelings about Spartans. You will keep those feelings out of the mission and follow the plan.
Satellite recon shows radar and magnetic signatures on high end... in the [Arc?] Star Cluster. These signatures indicate a complex of buildings. It's a logistical base. The Prophet you are targeting is in control of this entire Sector. Our mission is simple: we want this Prophet dead. We take out the prophet, we will stop the Covenant chain of supply. If we achieve the goal of this mission, we will be able to buy ourselves months of tactical advantage. And we will do all of this with minimal risk to the UNSC. [laughs] Other than to this group, of course. Cortez! Fill them in on the details.
Master Sergeant Cortez: Alright, you'll be flying into the atmosphere with a Leonid class meteor shower. Meteor showers of this nature are a regular occurrence on this planet so that means entry and landing should go unnoticed. Calculations show reaching the target will take a fourteen-hour fast march from your entry point. Once you reach the target you will take out the Prophet as soon as he steps off that ship. Then you are to gather all data relating to the unidentified alien ruins.
O'Brien: What do you mean they're not identified?
Master Sergeant Cortez: The architecture is not Covenant design and it sure as hell wasn't built by humans. They predate both sides. This site is of the utmost importance. We photograph everything.
Mission Briefer: That'll be all, Master Sergeant. You can rejoin your men. You will be dropping in precisely five minutes. With this mission there is no room for delay or error. Good luck, and godspeed.
The only words I can't accurately identify are a couple of proper nouns identifying the name of the star cluster where the mission's planet resides ("Arc Star Cluster?") and the alphabetic portion of the Spartan's designation. The latter is identified as "Cal-141" in the Halopedia, but there are no official sources listed in the Cal-141 entry (only sources which link back to its own articles on Waypoint and
The Babysitter episode.) I missed out on the "Behind the Scenes" video for this episode. Perhaps the name "Cal-141" was revealed there?
The ruins certainly do not look anything like the Forerunner structures we know and love. When the squad reaches their target and a view of the ruins is revealed, there is a building on the far left which looks like a pagoda. The largest building appears on the far right (when the pan is complete) and looks more like Classical Greek architecture to me... but please understand that my architectural qualifications are non-existent! The Spartan zooms in on this larger building for a decent amount of time and many details can be seen. The more I look at it, the more it appears that it may be some precursor to the "modern" Forerunner architecture we're accustomed to. On the other hand, it may just be artistic license taken by 4C Studios. Nothing stands out as definitive to me.
I thought the reference to the Leonid meteor shower was interesting.
The Leonids- as they are known in real life- are a shower of particles which originate from the comet Tempel-Tuttle. Since this comet's orbit only extends roughly the distance between Earth and Jupiter (see
here) it means that a planet which experiences these showers would have to lie in our solar system! Since that makes no sense whatsoever in the context of the Halo Universe, we are left to assume that Cortez's usage of "Leonid class meteor shower" indicates that the meteor shower they're dropping in with is somehow similar in composition- but not identical in source- to Earth's
Leonids. Perhaps the period of the planetside showers or the coincidence of the comet and planet orbits are similar, for instance.
All in all, an interesting piece of Halo fiction.