A space always runs in a browser tab of its own. Space, beside the conversation's tabs, does not open it: it puts the space's card in the conversation, and Join on that card is what opens the tab. The map gets the whole window, and the conversation stays exactly where it was.
Why a tab of its own
The map is drawn continuously, and inside the chat it shared the browser with everything the chat was doing. In a tab of its own it does not, which is the difference you feel when several people are walking around at once.
The address stays good
A space has no beginning and no end: it is a place, so bookmarking its address takes you back to it later. Opening it asks the same questions either way — a channel's space wants you in that channel, and a private space belongs to its two people. The tab always shows a way back to the chat along its bottom edge.
One door, and it is the card
Pressing Space a second time does not post a second card: the conversation already has the one that matters, and the answer says so. Everything that leads into a space leads through that card, so nobody walks into a place the conversation was never told about.
See also: Virtual Spaces · Who Is in the Space Right Now · Inviting Someone to a Space
