Orbital

Orbital, also known by its former names, Moonbase Alpha and Space Camp is a map that was announced in the Bungie Weekly Update (10/12/07). It will be available for download on Xbox Live Marketplace in a future DLC release. But however, Orbital along with Assembly and Sandbox have been confirmed to be shipped with the Limited Edition of Halo Wars, which means these 3 new maps may avaliable via the Xbox Live Marketplace around the same time as Halo Wars' release date, and the other 3 maps' release date are unknown at the moment.

It is said to be best for objective games, like CTF and Assault, but also has some natural deadlocks that makes Slayer interesting and Infection "terrifying".

The map is on an "empty UNSC space platform". This might be an Orbital Defense Platform like Cairo Station from Halo 2. It may be similar to the Halo 2 map Elongation or the Halo: Combat Evolved map Boarding Action.

The map has a "...shrine to Doctors Tobias Fleming Shaw and Wallace Fujikawa", the creators of the Shaw-Fujikawa Translight Engine. One part of the map has a deadly chasm, which can be easily traversed once it is "unlocked". This could mean that part of the map is in the vacuum of space. Orbital has several such locks and "switches to disable and enable access to various parts of the map". This could theoretically mean that it is a remake/spiritual successor of Boarding Action, with some sort of possible switch to a bridge or something of the sort to link the ships. Orbital has been described as cleanly beautiful, yet haunting and having signs of abrupt abandonment.

Skull
The logo of the hidden skull on this level appears to have a symbol that looks like a giant fan which could refer to be a Orbital Defense Platform or a Mobile Station like the UNSC Cradle or the Station Delphi.

Trivia

 * This may be the first map featured in Space for Halo 3, including Campaign levels.
 * In a past Bungie weekly update, the map has been described as "have not been going anywhere", which means Assembly might ship alone instead of being coupled with Orbital. This was proved to be false, as the new Achievements points out that Orbital is a "Mythic map".
 * This map's codename was originally "Moonbase Alpha", then later changed to "Space Camp". The map's official name was confirmed to be "Orbital" by the new Achievements.
 * This map contains a hidden skull. Locating the skull earns the player the 'Orbital Skull' achievement. The crest of the hidden skull on this level appears to have a symbol that looks like a giant fan which could be referring to a Orbital Defense Platform or a Mobile Station like the UNSC Cradle or the Station Delphi. The skull also resembles the Cylon Base Stars from the television series Battlestar Galactica. The symbol on the Orbital Skull also looks somewhat like the Forerunner Dreadnaught.
 * The fact that there is an achievement to score 2 Death from the Grave medals in a single match online suggests that the map will have tight quarters and small rooms.