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Playing “hide and seek”


The lander cannot communicate with the ESA from July 9th, when he sent the last telemetry. According to the engineers of the DLR (the control center in Germany), Philae may have shifted and the antennas may be hidden. In any case the orbiter is now almost impossible to make contact because of the large amount of comet dust that is given off by the approach to the Sun
Rosetta and Philae are constantly monitored by ESA’s technicians ahead of closest approach to the Sun (perihelion) that will occur on August 13th, when the comet 67P / Churyumov-Gerasimenko (together with the probe and lander) will be at “only” 186 million kilometers from our parent star.

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Credit: ESA/Rosetta/Philae/CIVA

In recent weeks the probe (launched into orbit in 2004) flew over the surface of the comet at a distance of 180/153 kilometers (up to 54 degrees of latitude) looking for the best placed to communicate with Philae. The operations are not easy; because the activity around the comet becomes increasingly “hectic” and Rosetta may lose orientation stellar (some dust particles of the canopy are confused with stars). What’s going on? The heat from the sun increases kilometer by kilometer and the increasing amount of powder dust (whose amount is increasing) makes it increasingly difficult for the sensor to communicate with the lander. For this Rosetta – at the time of perihelion – must get away from Chury (say at a safe distance) and then be able to reconnect only in the following days. The good news is that after the perihelion communications between Rosetta and Earth will be much faster: it will take only 14 minutes and 44 seconds.

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Credit: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

Does Philae is still there? – We took contact with the lander from July 9th at 19:45. In early July, Philae talked to the team of the Lander Control Center (LCC) at the German Aerospace Center (DLR) and then it was gone into silent mode. “We sent a command to turn on the Rosetta Lander Magnetometer and Plasma Monitor (ROMAP), but we did not have an answer,” said Stephan Ulamec, head of Philae at the DLR. Engineers are currently testing various commands with which they want to optimize the activities of Philae. Data sent from Philae are still being examined by technicians, including those on the sunlight reaching the solar panels of different lander. “The amount is changed from June to July and this does not seem to find an explanation with the seasons on the comet”, added Ulamec. “In the telemetry we observed that Philae would move and that his would be hidden antennas or their orientation may be changed.”

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Credit: ESA

The current conditions of Philae remain uncertain, but in the meantime, the team wants to try to start a block of commands that are still stored in the computer of Philae and which have already been carried out successfully after the flyover (unplanned) of the surface on November 12. Experts want to re-start the MUPUSR, ROMAP, SESAME, PTOLEMY and COSAC tools. If everything were to work, Philae would begin again to do scientific research on the comet and would restore contact with Rosetta then sending new data to Earth. “Philae course is still operating, because it continues to send data, even if it does it at irregular intervals. Often we feared that the lander had gone out, but every time we have proven wrong”, said Ulamec.
The next “steps” of Rosetta – The ESA spacecraft will orbit the current (170-190 km away) until July 24, when they will head to the southern hemisphere which is now the most illuminated by the sun. Towards the end of this week, Rosetta will start to alternate attempts to communicate with the lander to its scientific analysis of the comet (especially the southern latitudes). “Although the scientific priority goes to the orbiter, Rosetta will continue to grope – until after the perihelion – to communicate with Philae,” added Patrick Martin, manager of the Rosetta mission. “Studying these regions is an important part of our scientific objectives in the long term up to and beyond the perihelion of next month, when the comet activity will at best,” said Nicolas Altobelli, project scientist for Rosetta (temporarily replacing Matt Taylor).

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