Complex sentence: The "Suzaku" spacecraft functioned flawlessly until 29 July 2005 when the first of series of mysterious vacuum system malfunctions occurred, that ultimately on 8 August 2005 caused the entire reservoir of liquid helium to boil off into space.
Split into simpler sentences: The "Suzaku" spacecraft functioned flawlessly until 29 July 2005 when the first of many occurrences of a mysterious vacuum system malfunction occurred. On 8 August 2005 this malfunction caused the entire liquid helium to boil off into space.