Philae, the survivalist

Lander Control Center

14 November 2014

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  • Lander Control Center
    Control centre for Philae – the Lander Control Center at DLR

    The Lander Control Center (LCC) at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) facility in Cologne is responsible for the commanding and operation of the Philae lander.

  • First comet panoramic
    Philae’s first panoramic image of the comet’s surface

    This first panoramic image of the surface of the comet was taken by the CIVA camera system and shows a 360-degree view of the landing site. The lander’s legs can be seen in some images. The signal confirming Philae’s landing on the comet on 12 November 2014 reached Earth at 17:03 CET. CIVA (Comet Visible Infrared and Analyzer) consists of the imaging panoramic camera system for the study of the landing site and microscopes for imaging and spectroscopy of the samples obtained from the comet’s surface with the SD2 drill.

  • Philae’s parting image of Rosetta, taken shortly after separation
    Rosetta, imaged from Philae shortly after separation

    The Philae lander acquired this ‘goodbye’ image of the Rosetta spacecraft from a range of about 10 metres, shortly after the successful separation.

  • Welcome to a comet
    Welcome to comet 67P!

    The Rosetta lander, Philae, landed on the surface of Comet 67P/Churyumov-Gerasimenko on 12 November 2014. This image was acquired by the CIVA camera system onboard the lander. On the left of the image, one of the three lander legs can be seen.

  • rolis_web_img5.jpg
    ROLIS captures Comet 67P Churyumov-Gerasimenko

    This image was acquired by the Rosetta Lander Imaging System (ROLIS) on board the Philae Lander from a height of approximately 40 metres, before the first touchdown. The resolution is four centimetres per pixel.

  • Comet Churyumov%2dGerasimenko from a distance of 3 km
    Comet 67P/Churyumov-Gerasimenko from three kilometres away

    This image was acquired by the ROLIS instrument on board Philae at 15:38:41 CET on 12 November 2014 as Philae approached the comet for landing. It was taken from about three kilometres above the comet's surface and has a resolution of about three metres per pixel.

Update: The DLR Lander Control Center re-established contact with Philae at about 23:30 CET. The MUPUS instrument has already provided scientific data. The SD2 drill has performed its sequence. Scientists and engineers in the Lander Control Center are awaiting data from the drill and the COSAC instrument.

 

Not only was it the first ever landing on a comet – it was also the second and third. Since 18:32 CET on 12 November 2014, the Philae lander has been on the surface of Comet 67P/Churyumov-Gerasimenko, performing experiments and returning data. "We have now switched on the MUPUS thermal probe and the SD2 drill," reports Koen Geurts from the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) Lander Control Center (LCC), from where Philae is controlled and commanded. "In the lander control room, we are all very pleased to have been able to activate all 10 instruments, even under these unusual circumstances and that the research teams are receiving scientific data. Philae is a real survivalist."

On the evening of 12 November 2014, the atmosphere in the LCC was still extremely tense. "As soon as we received the first touchdown signal, we could see that Philae was still moving." So there was no celebration; instead, the engineers were anxiously studying the data from space. Relatively early on, it became clear to the control room team in Cologne that the harpoons had apparently not fired, and so Philae was not anchored to the surface of the comet. Instead, the data from the solar panels indicated that the lander still seemed to be rotating. This would not have been the case had the landing been successful.

The control team and scientists were analysing the data sent by Philae. Ultimately, they concluded that the lander had rebounded after the first touchdown and did not touch down again for another two hours – at around 18:25 CET. Then came another hop, until the lander came to rest at 18:32 CET. This made the Agilkia landing site a thing of the past. At over 500 million kilometres from Earth, Philae is now in an unexpected location. The teams in the LCC have been processing the data around the clock. During the night, it became clear that it had not only survived the unusual multiple landing, but had started on its science sequence. The control room team immediately adapted the commands to the new situation.

At least one thing about 67P/Churyumov-Gerasimenko was demonstrated during this landing – its solidity. After the first touchdown, Philae bounced off the comet and floated several hundred metres back into space. "This means that the surface cannot have been particularly soft, otherwise the lander would not have made such a big hop," explains DLR comet researcher Ekkehard Kührt, who heads DLR's scientific participation in the Rosetta mission.

First data from the surface of a comet

"We have measured the surface of the comet directly and can do good scientific work with the data acquired," says Martin Knapmeyer from the DLR Institute of Planetary Research. The scientist is part of the CASSE instrument team, which is investigating the mechanical properties of the comet, for example its solidity. The instrument was switched on before the lander separated from the Rosetta spacecraft and recorded the vibrations of the flywheel during the descent. The scientists were also able to detect the shock of the first landing in their data.

The ROMAP magnetometer has also been important for understanding the processes involved in the triple landing. "Our data shows the movement of Philae, and we are very sure that it started spinning again after the first two landings and was rotating around its own axis," says Hans Ulrich Auster from TU Braunschweig. Also, the mast that was deployed for the measurements during the descent reacted to the landing. "We will now begin assessing our data." The ROMAP team is investigating whether the comet has its own magnetic field.

The ROLIS camera is also providing the scientific team around Stefano Mottola from the DLR Institute of Planetary Research with valuable images of the surface of the comet. Even before the first landing, the camera started acquiring images as it approached 67P – and took the first ever image directly from the surface of the comet.

"Struggling for every bit of energy"

The technical leader of the lander mission, Koen Geurts, is more than pleased with the status of Philae. "It is functioning flawlessly, even in the new landing site." The final instrument yet to be used, the drill, has now been deployed. However, the battery life is limited; today at around 21:00 CET is very probably the last time the team will be able to communicate with the lander. "We are struggling for every bit of energy and are saving wherever we can." The landing site on the edge of a crater offers just 1.5 hours of sunlight per day – that is simply not enough to recharge the batteries using solar energy. When the battery is empty, Philae will automatically switch to sleep mode and will only report in again when it has enough energy. "It might be that it can charge up again as it approaches the Sun – however, that will probably not be for another two months," estimates Geurts. "But, from a scientific perspective, we have been successful in achieving the first landing on a comet."

Last modified:
24/11/2014 15:19:56

Contacts

 

Manuela Braun
German Aerospace Center (DLR)

Space research and technology, Communication

Tel.: +49 2203 601-3882

Fax: +49 2203 601-3249
Dr Koen Geurts
German Aerospace Center (DLR)

Space Operations and Astronaut Training

Tel.: +49 2203 601-3636
Dr.rer.nat. Ekkehard Kührt
German Aerospace Center (DLR)

Institute of Planetary Research, Asteroids and Comets

Tel.: +49 30 67055-514

Fax: +49 30 67055-340