He will probably reply to this topic within a few days, so this topic is probably the best place to contact him.
http://universesandbox.com/contact/This page says that UniverseSandbox can't provide support via email, unless it is related to sales or "general/info" (I'm not sure what this category means).
If you need support related to the game, such as bugs or crashes, you could describe the problem here, the community might be able to help.