How to create two way persistence for a game server using Node.js?

Lets say we are building a spaceship game. A few object types would be spaceships, and solar systems. I would like to use Node as the backend.

The issue I am having is how to have both these objects existing and interacting with each other in real time using a callback/event driven system. For example, how would a ship continually tell the system its location within that system without constantly updating a "location" attribute every few seconds that would be initialized upon the creation of the ship.

Or how would two ships interact with each other? Things like location, types, etc would all have to be considered. Would insanely complicated event listeners have to implemented?

Maybe I am making this more difficult than is needed.

For realtime apps you should try meteor.js

http://www.meteor.com