These are the Planetary Defense Platforms that orbited Nod Kartha. A Planetary Defense Platform was a type of space station utilized by the Trade Federation. They were part of the defensive structure they established around the planet of Nod Kartha in the time leading up to the Clone Wars.
Each of these Planetary Defense Platforms incorporated a shield generator capable of generating a powerful energy shield, highly resistant to incoming attacks. Each station also possessed offensive capabilities, including four laser turrets and two missile launchers.
To safeguard their Trihexalon manufacturing facility located on the surface, the Trade Federation constructed a defensive network consisting of Planetary Defense Platforms and Planetary Defense Cannons in the space surrounding Nod Kartha. In 22 BBY, the combined military forces of the Lok Revenants and the Mere Resistance launched an attack with the objective of destroying the factory and preventing the Federation from deploying the prohibited Hex weapon to devastate their system. While the allied forces successfully eliminated the Defense Cannons, they struggled to penetrate the shields of the Defense Platforms. Ultimately, a dying Captain named Orsai piloted the damaged cruiser Kethor into one of the platforms, destroying it. This destruction of one platform resulted in a chain reaction, causing the shields of the remaining Defense Platforms to collapse, allowing the attackers to destroy two additional platforms and create a breach in the defense network, enabling them to reach the planet's surface.