Wraith Marker Satellites are an orbital system that is left around worlds in the Pegasus galaxy which contain human life. These satellites would remain dormant for centuries (in a hibernative state) and collect energy through solar cells. Once they received a signal, they would power up and attempt to contact the rest of the Wraith, informing them that the world contained plentiful prey for culling.
These marker satellites were armed with weapons which open up like a flower blossoming, and were capable of destroying a Puddle Jumper. They possessed some level of automation, as evidenced by them capable of engaging in limited evasive maneuvers.
Near the end of the Lantean-Wraith war, Scar's hive ship was crippled in battle over Halcyon and its hyperdrive damaged beyond repair. The Ancients were forced to retreat due to their own battle damage, but never returned with reinforcements to destroy the hive ship. Going insane with hunger and rage and unable to Cull the planet due to the Dolmen, the Wraith on the hive ship dropped a marker satellite before entering hibernation and landing the hive ship on the planet. Millennia later, the commander of the hive ship, Scar, was awakened and before being captured, he activated a stealth program to bring the satellite to life years later and signal the other Wraith. While scanning the planet for Doctor Rodney McKay, Lieutenant Colonel John Sheppard and Ronon Dex located the satellite by accident and briefly engaged it. Ultimately, Sheppard destroyed the satellite using his Puddle Jumper's drone weapons. Looking over the sensor data from the satellite, Teyla Emmagan was able to determine that it had not been able to signal other Wraith hive ships before it was destroyed and was still in an information gathering mode given the amount of power it had left at the time of destruction. (SGA: "Halcyon")