Series of automatic manoeuvres
The signal was received at ESA’s ESOC mission control centre in Darmstadt, Germany, confirming that Rosetta had been woken up automatically by its internal clock as scheduled on 20 January at 11:00 CET after 31 months in a deep-space, power-saving slumber.
The reactivation of the spacecraft set in chain a series of onboard manoeuvres. First, the star trackers warmed up (these will allow Rosetta to orient itself in the vacuum of space). Then, the spacecraft came out of its rapid spin and pointed itself at the Sun to enable its solar panels to absorb some energy. After that, its high-gain antenna was turned towards Earth to send the precious signal confirming that it was alive and well.
Philae to awake on 28 March
Rosetta will now gradually catch up with the nucleus of comet Churyumov-Gerasimenko, progressively reducing its speed before eventually going into orbit around the nucleus at an altitude of a few tens of km. The close escort phase is expected to begin in July, at which point the spacecraft will observe the nucleus’s relief to allow mission scientists to select the best landing site. Increasingly precise images of the comet will be sent back to Earth throughout the summer.
At CNES, things will start gearing up from 28 March when the 100-kg Philae lander set to touch down on the comet’s surface in November will in turn be reactivated. All of its systems will be thoroughly checked out to ensure they are functioning nominally.
Back-up solutions will also have to be planned if anything goes wrong. To communicate with the lander, the Space Operations and Navigation Centre (SONC) at CNES in Toulouse will send the lander’s work plans to the Lander Control Centre (LCC) in Cologne, which will translate them into commands to be uploaded to the orbiter by ESA, and finally to the lander. At the same time, the flight software that will control Philae during its descent and after landing will also be loaded.