Related Clues:

• Breathing room
• "The final frontier"
• Where the stars are
• Garage unit
• Cosmos
• Leeway
• Elbow room
• Relax, with 'out'
• Word separator
• Type of heater
• Place to park
• Be lazy
• "Final frontier" related to this puzzle's theme
• Chill (out)
• __ out: relax