The European Space Agency (ESA) today announced that it has burned off the last of the Planck space observatory’s fuel. The fuel burn was made to put the satellite in a safe orbit around the sun. The Planck observatory will be shut down entirely on Wednesday, October 23 when its transmitters are switched off.

Astronomers are currently in the process of ending the Planck mission. Science missions using the satellite were ended on October 3, and its instruments were switched off on October 19. The observatory ran out of its helium coolant for its high-frequency instrument (HFI) in January 2012, but continued to use its low-frequency instrument to survey the cosmic microwave background (CMB) for over a year.

“At ESOC (European Space Operations Centre), our business is keeping missions alive and productive, so sending a ‘shut-down’ command is very difficult,” said Paolo Ferri, head of Mission Operations at the ESOC. “While the end of this outstanding scientific mission was always foreseen with the exhaustion of the helium coolant, it seems fitting that we have a colleague from the science team to send the final command that once and for all silences the Planck spacecraft.”

The Planck mission launched in May 2009 to survey the cosmic microwave background – the radiation left over from the big bang that blankets the universe. The satellite completed five full-sky surveys before its HFI coolant depleted, and wen to to conduct three more with its LFI instrument.

The shutdown of Planck is very similar to another ESA mission that concluded this year, Herschel. Herschel also ran out of its liquid helium coolant, back in April of this year. That observatory was deactivated in June and was, like Planck, sent out of its L2 Sun-Earth Lagrange Point orbit an onto a safe heliocentric disposal orbit.

“These are the first two missions ESA has flown at the scientifically valuable L2 Lagrange point, so it’s important that we set a positive precedent as to how we dispose of missions there,” said Andreas Rudolph, head of astronomy mission operations at ESOC.

(Image courtesy ESA)