diff --git a/src/data/defs.txt b/src/data/defs.txt
index 9620006..1dbac8d 100644
--- a/src/data/defs.txt
+++ b/src/data/defs.txt
@@ -108,6 +108,7 @@ actor 0 0 0
             orbitaround jupiter 128000e3
             tidally locked
             scale 21.5e3
+            density 13000
             moon yes
             collider handcrafted
             angularmomentum 0 0 0
@@ -123,6 +124,7 @@ actor 0 0 0
             orbitaround jupiter 129000e3
             tidally locked
             scale 8.2e3
+            density 7000
             moon yes
             collider handcrafted
             angularmomentum 0 0 0
@@ -138,6 +140,7 @@ actor 0 0 0
             orbitaround jupiter 181365.84e3
             tidally locked
             scale 83.5e3
+            density 7000
             moon yes
             collider handcrafted
             angularmomentum 0 0 0
@@ -153,6 +156,7 @@ actor 0 0 0
             orbitaround jupiter 221900e3
             tidally locked
             scale 49.3e3
+            density 7000
             moon yes
             collider handcrafted
             angularmomentum 0 0 0