diff --git a/src/defs.txt b/src/defs.txt
index a855cf6..abb5a5b 100644
--- a/src/defs.txt
+++ b/src/defs.txt
@@ -48,6 +48,7 @@ actor 10 -30 20 MeteorAceGT
 
 actor 0 0 0 io
     name Io
+    id io
     relativeto jupiter
     orbit 421700e3 0.65
     scale 1822e3
@@ -59,6 +60,7 @@ actor 0 0 0 io
 
 actor 0 0 0 europa
     name Europa
+    id europa
     relativeto jupiter
     orbit 670900e3 0.35
     scale 1561e3
@@ -70,6 +72,7 @@ actor 0 0 0 europa
 
 actor 0 0 0 ganymede
     name Ganymede
+    id ganymede
     relativeto jupiter
     orbit 1070400e3 0.93
     scale 2634e3
@@ -81,6 +84,7 @@ actor 0 0 0 ganymede
 
 actor 0 0 0 callisto
     name Callisto
+    id callisto
     relativeto jupiter
     orbit 1882700e3 0.45
     scale 2410e3
@@ -98,6 +102,30 @@ actor 0 0 0 moonlet
     scale 50e3
     angularmomentum 0 0.025 0
 
+actor 0 0 0 moonlet
+    name Metis
+    relativeto jupiter
+    id metis
+    orbit 128000e3 0.8
+    scale 21.5e3
+    angularmomentum 0 0.025 0
+
+actor 0 0 0 moonlet
+    name Adrastea
+    relativeto jupiter
+    id adrastea
+    orbit 129000e3 0.5
+    scale 8.2e3
+    angularmomentum 0 0.025 0
+
+actor 0 0 0 moonlet
+    name Amalthea
+    relativeto jupiter
+    id amalthea
+    orbit 181365.84e3 0.2
+    scale 83.5e3
+    angularmomentum 0 0.025 0
+
 actor 3000 0 0 moonlet
     name Moonlet
     collider mesh