Autor Wątek: Philae  (Przeczytany 77451 razy)

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Offline Air Q

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« Odpowiedź #45 dnia: Wrzesień 10, 2014, 21:48 »
« Ostatnia zmiana: Wrzesień 16, 2014, 11:10 wysłana przez Scorus »
"One could write a history of science in reverse by assembling the solemn pronouncements of highest authority about what could not be done and could never happen."
http://qt.exploratorium.edu/mars/opportunity
Sprawdź SOL: http://www.greuti.ch/oppy/html/filenames_ltst.htm

Offline KonradL

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« Odpowiedź #46 dnia: Wrzesień 11, 2014, 00:32 »
Swietne zdjecie - mysle, ze zostanie zapamietane.

Offline kanarkusmaximus

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« Odpowiedź #47 dnia: Wrzesień 15, 2014, 12:41 »
Wybrano punkt J jako główne miejsce lądowania, a C jako zapasowe. J jest na "głowie kaczki".

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« Odpowiedź #48 dnia: Wrzesień 17, 2014, 13:21 »
Miejsce lądowania Philae ustalone --> http://spaceflightnow.com/rosetta/140915landingsite/#.VBlu6txDWek

Wygląda na to, że nie wybrano wariantu B (z grupy kandydatów oznaczonych na zdjęciu w jednym z wcześniejszych postów), miejsce wygląda nieco ryzykownie, nie będzie to na pewno przysłowiowa "plaża".
Największe osiągnięcie NASA w drugiej dekadzie 21 wieku? .... Logo ARTEMIS

Scorus

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« Odpowiedź #49 dnia: Wrzesień 25, 2014, 13:19 »
Tymczasem przeprowadzono testy naziemne odpalenia harpunów. Miały one na celu scharakteryzowanie pracy sensorów MUPUS umieszczonych w harpunach.

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Another Harpoon Shooting
22 September, 2014

On 11 September 2014, we had scheduled another shooting of the harpoons of the Philae anchoring system -  not in flight, but on Earth. This experiment took place at DLR Oberpfaffenhofen. It was prepared and exercised by MPS engineers and scientists with the help of colleagues from the MPI for Extraterrestrial Physics in Garching, the Institute for Space Research in Graz/Austria, the DLR Oberpfaffenhofen and a colleague of Pyro Globe company.

An earlier test of the harpoons had taken place at the end of July. For that test, the harpoon was shot into a long wooden container filled with loose grainy material. This material was meant to represent the cometary surface. Actually, it would be best to test the anchors for a medium that is identical or at least similar in its structure and mechanical behaviour to the one of the cometary surface. The problem is that no one on Earth knows what the surface structures and composition of a comet is like and even less what the mechanical properties are. Learning more about these properties is one of the goals of Rosetta’s landing mission. So, for the anchor test in the lab we could only apply a material that mimics cometary soil as much as we know for its bulk density (around 0.5 g/cm3). And it should be a loose granular mixture of irregular silicate grains of different sizes from micron to sub-millimeter and to a few millimeters.

The shots worked well and the harpoons flew into the cometary analogue medium at a high speed of about 80 m/s. Somewhat unexpectedly, they got stuck in the wooden walls after having traveled about 1 m in the 'cometary medium' of the experiment. This was due to a torque momentum imposed on the harpoon by the explosive firing. As a consequence the anchors missed the target entry point of the medium by a small amount and they also entered the medium with an inclined angle (expected was perpendicular entry geometry).

The key task of the second harpoon shooting was to verify the proper working of the acceleration sensors of the MUPUS experiment that are located in the harpoon heads and to allow a free traveling of the harpoons without hitting the wooden walls of the containers that hold the cometary soil analogue material. So, the harpoon experiment electronics was complemented by the MUPUS accelerometer read-out equipment. Moreover, a much larger containment for the soil analogue material was set up. As a consequence, it became a challenge to procure the analogue material (more than a ton) for delivery in time. But finally all containment equipment arrived at DLR premises two days before the harpoon shooting was scheduled to take place - just in time for preparing the experiment set-up the day before 11 September 2014. Once again, two harpoon heads plus electronics were prepared by Christian Rohe from MPE Garching and Reinhard Roll, Henning Fischer and Wolfgang Kühne from MPS Göttingen, the MUPUS electronics and sensor was set-up by Günter Kargl and Norbert Kömle from IWF Graz. The DLR facility was arranged by Stefan Völk and again Dr. Lell from Pyro Globe prepared the harpoon explosives and provided a high speed camera for the movie protocol of the experiment.

We met at DLR on 11 September at 9LT. Soil containment, the harpoon and MUPUS electronics as well as the ramp for the attachment of the harpoon had been prepared the day before. It still required the installation of the high speed camera and finally of the armed harpoon, one at a time. By about 11:30LT everything was ready for the first shot. The camera was running and Henning Fischer triggered ignition of the harpoon. The explosive generated an acceleration of several thousand Gs (Earth gravity acceleration) on the harpoon head. The projectile was accelerated to a speed of several 10 m/s and entered the soil material. After a few milliseconds it got stuck in the soil material after having traveled about 1.5 m, this time not hitting the wall of the containment. The MUPUS sensor recorded the deceleration of the harpoon head in the soil analogue material as we were aiming for. Since this time the rewind drive was not connected (on purpose), the harpoon was pulled back in the soil by human force, however using a gauge for measuring the applied force. The pull-back is meant to open the flaps at the harpoon head resulting in a large cross section and thus high resistance against the pulling force. So, our test projectile could only be pulled back by a few cm in the soil containment, then the flaps were apparently full open and it was not possible to retrieve the harpoon any further by human force. But, of course, we could still get the harpoon head out of the ground by means of shuffling away the soil material.

The second shot was foreseen for the afternoon after a late lunch break in the DLR canteen. The IWF colleagues were discussing whether to modify the experiment by including a plate into the soil material as a kind of stiff layering. This mimics a bit the layering of the cometary soils (which is still unknown, but suspected from theoretical calculations and lab experimenting) and at the same time it provides a fiducial point on the time axis of the MUPUS recording of the anchor shots. It was decided to introduce a rather soft multi-layer paper material among the soil analogue at a distance of some 50 cm behind the entrance surface of the containment. Then the second shot was prepared and successfully ignited and measured – even getting the fiducial mark in the MUPUS experiment recording. Before the end of the day the whole experiment set-up was dismantled and the test facility was cleaned up from any relics of the anchor shooting. By then, I was already on my way to Toulouse where the landing site selection process took place on 13 and 14 September 2014.


Offline JSz

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« Odpowiedź #50 dnia: Wrzesień 27, 2014, 16:50 »
Informacje ze strona ESA dotyczące lądowania:

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Philae’s landing site, currently known as Site J, is located on the smaller of the comet’s two ‘lobes’, with a backup site on the larger lobe. The sites were selected just six weeks after Rosetta arrived at the comet on 6 August, following its 10-year journey through the Solar System

Miejsce lądowania J (zapasowe: C), zaznaczone na zdjęciu:



Przebieg lądowania:

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For the primary landing scenario, targeting Site J, Rosetta will release Philae at 08:35 GMT/09:35 CET at a distance of 22.5 km from the centre of the comet, landing about seven hours later. The one-way signal travel time between Rosetta and Earth on 12 November is 28 minutes 20 seconds, meaning that confirmation of the landing will arrive at Earth ground stations at around 16:00 GMT/17:00 CET.

Czyli lądujemy 12 listopada, a potwierdzenie informacji o wylądowaniu dotrze do nas ok. 16 UTC (jeśli w rezerwowym miejscu C, to 1,5 godz. później).

Źródło: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_to_deploy_lander_on_12_November

Offline KonradL

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« Odpowiedź #51 dnia: Wrzesień 27, 2014, 23:03 »
Calkiem połdowana ta J-ka - a i uskoki dosyc ostre.

Offline kanarkusmaximus

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« Odpowiedź #52 dnia: Wrzesień 27, 2014, 23:09 »
Calkiem połdowana ta J-ka - a i uskoki dosyc ostre.

Czy aby na pewno? Wydaje mi się, że jest to delikatny teren, tylko dookoła są uskoki, na które trzeba uważać.

Offline KonradL

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« Odpowiedź #53 dnia: Wrzesień 29, 2014, 14:18 »
Czy na pewno to nie wiem, ale te ostro odciete cienie na obrazku powyzej sugeruja, ze teren nie jest gladko pofaldowany i miejscami jednak wystepuja uskoki.

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« Odpowiedź #54 dnia: Wrzesień 29, 2014, 15:10 »
Szkoda, że przełożyli lądowanie na 12 listopada. 11 to dzień wolny i można by pośledzić misję, a 12 to ja będę dojeżdżał do pracy i pracował do wieczora  :P
Muszę pomyśleć, jak tu pogodzić pracę z lądowaniem  na komecie :(

Scorus

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« Odpowiedź #55 dnia: Wrzesień 30, 2014, 12:02 »
O obszarze J:
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Site J is similar to site I, and also on the smaller lobe, offering interesting surface features and good illumination. It offers advantages for the CONSERT experiment compared with Site I, but higher-resolution imaging is needed to determine the details of the terrain, which shows some boulders and terracing.
http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_Landing_site_search_narrows

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None of the candidate landing sites met all of the operational criteria at the 100% level, but Site J is clearly the best solution. Site J in particular offers us the chance to analyse pristine material, characterise the properties of the nucleus, and study the processes that drive its activity

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At Site J, the majority of slopes are less than 30º relative to the local vertical, reducing the chances of Philae toppling over during touchdown. Site J also appears to have relatively few boulders, and receives sufficient daily illumination to recharge Philae and continue science operations on the surface beyond the initial battery-powered phase.

Provisional assessment of the trajectory to Site J found that the descent time of Philae to the surface would be about seven hours, a length that does not compromise the on-comet observations by using up too much of the battery during the descent.
http://www.esa.int/Our_Activities/Space_Science/Rosetta/J_marks_the_spot_for_Rosetta_s_lander

Offline KonradL

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« Odpowiedź #56 dnia: Wrzesień 30, 2014, 12:57 »
Dzieki Scorusie za ciekawe fragmenty - czyli jednak te male uskoki w jakims stopniu zaprzataja im glowe.

Scorus

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« Odpowiedź #57 dnia: Październik 16, 2014, 19:02 »
Obszar J został oficjlanie zatwierdzony. Ponadto jest nowa animacja pokazująca manewry orbitera przed odłączeniem lądownika.

http://blogs.esa.int/rosetta/2014/10/15/green-light-for-landing-site-j/

Zdjęcia strefy J i C z OSIRIS:
http://blogs.esa.int/rosetta/2014/10/16/landing-sites-from-30-km/

Scorus

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« Odpowiedź #58 dnia: Październik 16, 2014, 19:03 »
Zdjęcie z CIVA z 7 października, z odległości 16 km:
http://blogs.esa.int/rosetta/2014/10/14/mission-selfie-from-16-km/

Offline KonradL

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« Odpowiedź #59 dnia: Październik 17, 2014, 07:47 »
Piekny autoportret z gazujacym balwankiem w tle :D