document: Now Rosetta - Philae's European Space Agency (ESA) mothership - will switch off its electrical support system meaning it will no longer be possible to communicate with Philae.
  Rosetta will remain in orbit around the comet 67/P Churyumov-Gerasimenko until the 30 September, when controllers at ESA will crash the spacecraft into the surface, using the opportunity to gather close-up photos and data as it falls.
  Philae has asked for picture postcards to be shared as a way of marking its shutdown.
  Philae's official job on Comet 67P was to acquire as much information about the comet as possible. It would record and transmit pictures. It was a job greatly appreciated by NASA who also tweeted thanks and goodbye.
  Philae and its spacecraft called Rosetta developed a relationship on social media with the two exchanging musings about their new location, the view, power sources and crucially, the icy cold conditions. But now Rosetta is letting go.
  Messages have come in from around the world including people posted pictures on Germany's Aerospace Centre's Facebook page.
  And Melanie Gywer, also in Germany, tweeted this.
  And it's ciao from Italy.
  From the USA, @Kelpher tweeted this message from Chicago.
  In Bolivia Andrea L wants Philae to remember how green Earth is.
  From South Wales, UK, Barrie Johnson, shared his goodbye postcard to Philae.
  While Amy Carparelli from Kent, UK, tweeted her picture of Philae.
  The ESA says that no signal has been received from Philae since July 2015 and so the decision has been taken to switch off to save energy until the end of the mission.
summary: Almost two years ago a robot called Philae became a household name after it succeeded in making a difficult - and bouncy - landing on a moving comet.