Assertion: moon's mass | /r/HasProperty | one
Facets:
Source sentences:
text: ^  whereas the combined mass of Janus, Hyperion and Phoebe—the most massive of the remaining moons—is about one-third of that.
text: The mass of the rings is about the mass of Mimas,whereas the combined mass of Janus, Hyperion and Phoebe—the most massive of the remaining moons—is about one-third of that.