This is a very interesting idea. It might be handy to generate a little publicity in related SE sites, I don't know if there is a mechanism to do that or not. Perhaps every month, or every Lunar Cycle as @user15217 suggests topics could focus on a discipline or cross-discipline with a different site. Computation hardware, computation/mathematical techniques, physics, space-based observations, mechanical/electrical engineering challenges, the history of astronomy are just off-the-cuff examples that might tie in with other sites.
The Community Bot could be assisted to help bump topic-specific existing questions each Lunar Cycle as well.
I'm happy to help; I've asked in toto about 1,000 stackexchange questions now and I'm just getting warmed up, and I guarantee they are all 100% genuine. I would ask many more here if there were effectively an “Escalate to an Astronomer (in related field)” button at least available to the mods. Raising the number of questions should be balanced with some way to ensure that there are enough people to share in the work of answering them. (Please don't check the number of SE answers I've posted, it's definitely much less than the questions - blush.)
In (at least) some SE sites, some questions are rebroadcast on Twitter if some criterion is met. There may be some way to use this as well, both for questions and to solicit answers if necessary. This is just a thought.
Perhaps an informal discussion in the Observatory might explore some possibilities?
edit: I've just asked What is the extent of the “worldwide campaign” to observe near-earth object 2012 TC4?