Scientists say a Cardiff instrument on Europe's Herschel Space Observatory has finished its operations and the spacecraft has exhausted its supply of liquid helium coolant.
Cardiff University astronomers led the international team that designed, built and operated the SPIRE instrument.
The University says using SPIRE data, astronomers have already made ground-breaking discoveries.
The European Space Agency says on Sunday it starts a long series of technology tests that will last into June.
And there's still far more to come from its huge archive of data.