"The surface of the Earth is the shore of the cosmic ocean... Recently, we've managed to wade a little way out, and the water seems inviting." - Carl Sagan
Planck on course for safe retirement
In preparation for its final switch-off on 23 October, mission controllers today fired Planck’s thrusters to empty its fuel tanks. The burn is one of the final steps to ensure that Planck ends its hugely successful mission in a permanently safe configuration.
The satellite, which mapped the relic radiation from the Big Bang – the Cosmic Microwave Background, or CMB – in unprecedented detail, will be switched off in two days.
One of Planck’s two instruments, the HFI high-frequency instrument, exhausted its liquid helium supply in January 2012. Planck had by then completed five full-sky surveys using both HFI and its partner detector, the LFI low-frequency instrument.
Since January 2012, the spacecraft has conducted three more sky surveys with LFI, enabling scientists to refine their CMB data. All science operations finally came to an end on 3 October, and the payload was switched off on 19 October.
Today, around 12:00 GMT (14:00 CEST), the thrusters will again be switched on to burn the remaining fuel to depletion, an important aspect of rendering the spacecraft inert, as required by ESA’s space debris mitigation guidelines.
“We’ve already programmed the onboard software so that it will no longer try to automatically reactivate the transmitters, and next we will disconnect the batteries and disable the onboard protection mechanisms” says Steve.
“The final step will be the simple act of switching off the transmitters: we will witness the silencing of Planck and we will never receive a signal from her again. This is important because we cannot cause radio interference for any future mission.”
This will happen on 23 October during a small ceremony, when the final command will be sent by ESA’s Jan Tauber, the Project Scientist, who has personally invested more than a decade and a half in Planck.