Relationship between Adeptus Astartes Chapters and Explorator fleets?

[Messor]

What relationships, if any, are typical between an Astartes Chapter and an Explorator Fleet? Specifically, would a chapter be founded to or assigned to accompany one? Or reasonably take it upon themselves to do so? Under what sorts of circumstances would such an alliance form, particularly relative to the current state of the galaxy.

[WarriorFish]

I don't think there is anything typical, Explorator Fleets are expeditions into the unknown and/or to perform some technoarchaeology so that's a pretty independent thing usually. I'd say that the latter is more likely to involve other Imperial forces as that could be close to home as it were (Space Marines aren't going to be mucking around in nowheresville much), maybe the Explorator digs up more than he bargained for and calls for help and the Marines answer? I can't really see how a chapter would be made for this purpose, perhaps if they were intended to guard the nearby area that'd be a close enough equivalent?

 

Unless you wrangled some reason for them to continue to work together it'd probably be a one off as most Marine action would be (save the day, then off to save another), but this could be added easily enough with a little creativity. Perhaps they find clues to what they're seeking and seeing the potential benefit to the Imperium (and/or more xenos/heretics to slay) the chapter agrees to help them see it through?

 

Or maybe like a generic story they uncover some great threat to the Imperium so they band together to see it destroyed Once they've worked together in such a fashion they could make some bonds or oaths of assistance, where the chapter agrees to come to their aid or could even send a detachment with them?

[Conn Eremon]

Maybe in the midst of a Founding, while determining final destinations, home world and initial duties, they earmark one Chapter to assist in the exploration, conquest and eventual defense of a promising section of non-Imperial space.

 

Due to the timing, it happens to be prudent to simply attach this Chapter to an Explorator Fleet heading into that same region, alongside whatever other Imperial forces that may be going along for the ride. Probably more than a few planetary settlement fleets, Guard regiments, etc.

 

The Chapter is not bound to any of these forces, it is merely the best for them to work together in the beginning. But, a lasting relationship can be forged here, particularly if that Explorator Fleet ends up establishing a nascent forge world.

[Brother Lunkhead]

What relationships, if any, are typical between an Astartes Chapter and an Explorator Fleet? Specifically, would a chapter be founded to or assigned to accompany one? Or reasonably take it upon themselves to do so? Under what sorts of circumstances would such an alliance form, particularly relative to the current state of the galaxy.

 

I think I've got a more definitive answer for you Brother Messor. Graham McNeill's Forges of Mars Trilogy which is about the voyage of a AdMech explorator fleet addresses this issue. All manner of fighting force joined this expedition, Skitarii, Imperial Guard (infantry and armor), Collegia Titanica (Titan maniple), there might even have been a Knight House in there too (this part I'm a bit hazy on since it's been a few years since I read the series), and..... (I am sure about this part) Space Marines. Archmagos Lexell Kotov (expedition leader) petitions the Black Templars and they answer with a crusader force of one ten marine crusader squad.

 

So, the Space Marine chapters can be petitioned (the standard way of requesting aid from the Astartes) and they will come or not come as they see fit. In this case the Black Templars saw this expedition as a crusade, so they joined.

 

I was toying with an IA idea built around a chapter dedicated to among other duties protecting explorator fleets. I may get around to this one of these years unless someone beats me to it (hint, hint).