This should create enough dissention and warring messages that you can tell the chairman you are uncomfortable making a decision without a consensus, and that he had better do it. You won't be assigned to that committee again. Job security is comforting, but the main point about tenure is that you get to do what you want in the way of research. If your primary goal is to learn how the universe really works, and not just to get your name in the newspaper, look where others are not exploring. Nature is so rich you are unlikely to look carefully at anything without learning something new, particularly in unexplored territory.
New instruments are wonderful here.
If you have to rush to publish something, quick before you get scooped, you are doing the wrong research. Stop it, and do something nobody thinks is interesting. Learn from it. Teaching a class on elementary astronomy to undergraduates is the best way I know of to get the basic ideas clearly in mind. If their eyes glaze over at some explanation, and they fail to understand it, chances are you don't really understand it either.