TheCassinispacecraftwassentonitswaytoSaturnin1997.Sincethen,shehastravellednearlyfourbillionkilometers,deliveredaprobetoatoxicmoon,discoveredphantasmagoricalstructuresontheplanet39;sicyrings,studiedthestartlingatmosphereonatinymoon.Now,onadaringspiralorbit,CassiniwillstreaktowardSaturnitself,streamingdatatoEarthbeforebeingtornapart.