Martian Probe

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Desktop/Console/Mobile-Only Content: This information applies only to the Desktop, Console, and Mobile versions of Terraria.
Martian ProbeHardmode exclusive
Martian Probe.gif Martian Probe2.gif
Classic Mode.png Classic
Expert Mode.png Expert
Master Mode.png Master
AI TypeMartian Probe AI
Max Life500/1000/1500
KB Resist100%
Immune toShimmeringConfusedPoisoned
Not to be confused with Probe or Martian Drone.
A Martian Probe scanning for players. Its green scanning beam turns red when players are detected.
A Martian Probe after it detected a player.

The Martian Probe is a rare Hardmode, post-Golem flying enemy that can spawn above the surface in the outer two thirds of the world, most commonly in the Space layers. The Martian Probe initially appears with a green light. When it detects the player, the light turns red, it gains the ability to pass through blocks, and attempts to escape. If allowed to, it initiates the Martian Madness event.

It is one of the few entities that can be detected by the Lifeform Analyzer or its upgrades.


  • Only one Martian Probe can exist at a time.[1]
  • Martian Probes spawn more frequently in the Space layer; this is due to them having additional spawn attempts when the player is at >55% alttitude.[2]
  • In Don't dig up and Get fixed boi worlds, besides the Space layer, the Martian Probe can also spawn at the Cavern layer and the "Glowing Mushroom layer".[3]
  • In addition to the normal spawn rate increasing effect, the Water Candle can also nearly triple the Martian Probe's spawn chance.[4]
  • The spawn rate of the Martian Probe is reduced significantly after Martian Madness is completed once.
  • Martian Probes will not spawn if a boss is alive somewhere in the world, or during certain events. This includes the Goblin Army, Frost Legion, Pirate Invasion, Martian Madness, Lunar Events, Old One's Army, Pumpkin Moon, and Frost Moon.
  • Standing in front of most types of background walls will also prevent Martian Probes from spawning. The following walls will still allow Martian Probes to spawn.[5]
    • Minions do not deliberately attack the Martian Probe, but those that deal contact damage may unintentionally kill it.
    • If the player follows the Martian Probe up to the sky until it escapes, it disappears before reaching the top of the map and the Martian Madness event will not occur.
    • Its Bestiary entry will not unlock if allowed to escape. It must be killed 10 times to complete the entry.
    • The Martian Probe has no means of attack besides contact damage. Its only purpose is to serve as a trigger for the event.
    • Homing projectiles will ignore Martian Probes.
    • Martian Probes can spawn above the top world border, meaning they can detect the player without being seen.


    • Effects that increase enemy spawn rates, such as Water Candles and Battle Potions, as well as events like a Blood Moon or Solar Eclipse, will give the Martian Probe more chances to spawn.
    • Standing in front of fence or cloud walls will not prevent probes from spawning, but will prevent Wyverns from spawning. Coupled with a water candle in the space layer, one can safely and reliably get a probe to spawn in seconds even after defeating the martians.


    • The BestiaryBestiary entry for the Martian Probe: "Sensing growing power on the planet, otherworldly beings send space-age technology to scan for advanced lifeforms."
    • Activated Martian Probes stop players from using Pylons.


    • Desktop Fixed a bug that prevented Martian Madness and other invasions from triggering when they should.
    • Desktop
      • Reduced spawn chance.
      • Can no longer spawn near the world center.
      • Can no longer spawn during events or boss fights.
      • Fixed Martian Probe detecting players above it.


    1. Information taken from the Desktop version Desktop source code, method SpawnNPC() in Terraria.NPC.cs.
    2. Information taken from the Desktop version Desktop source code, method SpawnNPC() in Terraria.NPC.cs. When the player is above surface, there is one attempt with 1/100 spawn chance before Martian Madness and 1/400 after; when the player is in Space, there is another attempt, if Water Candle is active there will be a third attempt. See the following note for these attempts' spawn chance.
    3. Information taken from the Desktop version Desktop source code, method SpawnNPC() in Terraria.NPC.cs. The exact area starts at 20 tiles above the border of Underground and Cavern layer, ends at 190 tiles above the bottom of the world. Since there is only 1/2 chance for this region to be considered as Surface during mob spawning, the effective chance of getting a probe is even lower.
    4. Information taken from the Desktop version Desktop source code, method SpawnNPC() in Terraria.NPC.cs. Water Candle increases the spawn chance of Martian Probe in Space (from 1/8 before Martian Madness and 1/30 after to 1/3 before and 1/10 after), and also grants an additional spawn attempt.
    5. Information taken from the Desktop version Desktop source code, methods SpawnNPC() in Terraria.NPC.cs and Initialize_TileAndNPCData1() in Terraria.Main.cs.