November 13, Google Doodle: Philae, The ‘Happy Lander’

“Philae is on the surface and doing a marvellous job, working very well and we can say we have a very happy lander,” says Paolo Ferri, ESA’s Head of Mission Operations at ESOC today.

During the second lander-orbiter communication slot, which ran from 06:01 UTC / 07:01 CET until 09:58 UTC / 10:58 CET this morning, “We had a perfect pass; the radio link was extremely stable and we could download everything according to the nominal plan,” adds Rosetta Flight Director Andrea Accomazzo.

Credits: ESA/Rosetta/Philae/CIVA

Here are details:

First analysis of the touchdown data suggests that the lander bounced twice before settling on the surface of Comet 67P/C-G. The lander remains unanchored to the surface, but the instruments are running and are delivering images and data.

After touchdown at 15:34 UTC (confirmed at 17:02 CET), a clear strong signal was received, with some breaks. Lander telemetry stabilised at about 17:32 UTC and communication with the surface was maintained until the link to the orbiter was lost at 17:59 UTC due to Rosetta’s orbit; this was about an hour earlier than predicted for the target landing site (most likely due to local horizon interference).

Later on 12 November, after analysing lander telemetry, the Lander Control Centre (in Cologne) and Philae Science, Operations and Navigation Centre (SONC, Toulouse) reported;

  • There were three touchdowns at 15:34, 17:25 and 17:32 UTC; in other words, the lander bounced
  • The firing of the harpoons did not occur
  • The primary battery is working properly
  • The mass memory is working fine (all data acquired until lander loss of signal at 17:59 UTC were transmitted to the orbiter)
  • Systems on board the lander recorded a rotation of the lander after the first touchdown. This is confirmed by ROMAP instrument data, which recorded a rotation around the Z-axis (vertical).

The lander did receive some power from the solar panels on Wall No. 2, but it appears that parts of the lander were in shadow during the time that last night’s surface telemetry were being transmitted.

Teams are still working to confirm the location and the overall power and thermal situation on board. Nonetheless, the lander appears to be performing well.

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