These small bulb-like devices belonged to a motion capture artist named Mokap. Mokap's Sensors, along with him, first appeared in Mortal Kombat: Deadly Alliance and later reappeared as a collectible Relic in the Konquest mode of Mortal Kombat: Armageddon.
Mokap uses these sensors in motion capture during his career before he was unexpectedly and unjustly placed within the conflict of Mortal Kombat. Now Mokap has to fight just to stay alive if he is to find his way home because to him, fantasy and reality are one and the same.
Mokap the Constellation?
In Mokap's Mortal Kombat: Armageddon ending, he defeats an fiery elemental creature known as Blaze and causes an explosion which kills himself and the rest of the fighters. Mokap becomes a constellation with his sensors became stars in Edenia's sky, and his name became a legend within the Edenian astronomy. Mokap remains a figure taught in Edenia's history as the man from Earthrealm who saved all the realms from Armageddon.