retroreflector /ret-rō-rə-flekˈtər or -ri-/

A device, placed on a satellite or a celestial object, that reflects light or radiation back to its source

retroreflectˈive adjective

• block gauges
• block grant
• block grants
• blockhead
• blockheads
• blockhole
• blockholes
• blockhouse
• blockhouses
• blockier
• blockiest
• blocking
• blocking motion
• blocking motions
• blockings
• blockish
• block letter
• block letters
• block parties
• block party
• block plane
• block planes
• block printing
• block release
• blocks