Observer

The observer was a small, stealthy robotic protoss reconnaissance unit, an aerospace drone used to survey space and record events for analysis in the protoss archives. Cloaked and fragile, it was valued less as a weapon than as an instrument of knowledge, capable of revealing burrowed and concealed enemies and gathering critical data that turned the tide of battle numerous times. (StarCraft; Observer (StarCraft II official site))

Design and locomotion#

The observer's primary means of locomotion was a discrete thruster that created a gravity field, while energy-sheathed fins manipulated that field to generate lift and propulsion. Without modifications, an observer could travel adequately from point to point but was hard pressed to outrun pursuers unless fitted with a set of gravitic boosters. Older observers had a different stabilizer configuration that, while equally effective, gave a more imposing aspect, and some phase-smiths held that this older arrangement improved performance. The drones were fragile craft with very little armor; their speed and cloaking gave them a measure of survivability, but a detected observer was usually an easy kill unless it withdrew quickly. (Observer (StarCraft II official site); StarCraft II War Chest; StarCraft Field Manual)

Some observers were equipped for warp-space travel and deployed for deep-space exploration, and units used for this purpose often lacked defensive systems. They could re-enter real space within planetary atmospheres and transmit data in real time over interstellar distances, and could drop navigational beacons to serve as homing devices. (StarCraft: Shadow of the Xel'Naga; Observer (StarCraft II official site))

Detection#

The observer's complex but sensitive sensor matrix was power intensive, yet it could collect massive amounts of data in a short time, and the critical data it gathered turned the tide of battle on numerous occasions. The drone could detect cloaked and concealed objects, including burrowers and all types of camouflage and stealth systems, and was sophisticated enough to detect zerg spores hidden within terrans. Its sensors comprised complex arrays of self-focusing lenses powered by psionic lattices, allowing the observer to analyze the battlefield from its vantage point in the sky. A sensor array upgrade significantly increased its sight range and sensitivity, making the observer a valuable auxiliary on the battlefield. (Observer (StarCraft II official site); StarCraft II: Wings of Liberty)

Stealth#

Observers intended for combat zones were equipped with a defensive micro-cloaking field. The drone's faint sensor signature reduced the field's power requirement and allowed the cloak to be maintained for extended periods with little drain to its power core. The field rendered an observer invisible to all but the most advanced detection technology, and its stealth was further enhanced by a hull fashioned from a buoyant, light-refracting material that masked its diminutive energy signature. (Observer (StarCraft II official site))

Observers across the protoss sects#

Observers were in use by the Tal'darim, whose most cunning ascendants made extensive use of them to spy on the enemies of Slayn, or on each other. After their activation the Purifiers especially prized their observers, which soon became a favored construct of Talandar. The Ihan-rii had used observers for millennia, watching the other protoss sects and the zerg without danger of being discovered. In Co-op Missions, Zeratul's forces fielded an observer named Witness IV. (StarCraft II War Chest; StarCraft II: Co-op Missions)