the deep moans round with many voices

I think I am just going to have to be vague about the exact space location, then, since not even Memory Alpha has much to say about where the Orions are based. *sigh*

The ship has to be fast, and it has to carry a lot. Interstellar distances are so vast, and (at least in the 23rd century) the Federation seems so loosely knit near its frontiers, that the Red Cross has taken to having ships patrol various sectors to extend their reach; the ships check several times on each colony in their area, and listen for any emergency transmissions. The Red Cross wants those first response ships able to handle a lot, since they are generally dealing with colonies that have not yet achieved self-sufficiency, and may not have adequate infrastructure, funds, or medical facilities to deal with natural disasters, diseases, or outbreaks of violence. I think that once a colony gets up to speed, the Federation of Red Cross and Red Crescent Societies encourages the formation of a planetary Red Cross, and takes that world off the regular patrol list. But anyway, rurounitriv makes some good points about why you wouldn't want to land the main ship on most worlds that are likely to need such a ship's intervention.