Stealth Tactical Aerial Reconnaissance Satellite
From Halopedia, the Halo wiki
The Stealth Tactical Aerial Reconnaissance Satellte, or STARS for short, is a piece of equipment used by the UNSC during offensive combat operations. STARS are are baseball sized satellites that orbit one hundred kilometers over combat situations.
STARS are extremely useful; they relay topgraphy information, enemy locations, and allied locations and equipment positions to the HUD of allied units in range. They also broadcast orders for individual units. STARS help the UNSC military coordinate even complex operations easily and under stealth conditions, where even COM chatter can give away unit positions.
