Etude par RMN de matériaux d'électrode pour batteries lithium-ion

BORDEAUX1-BU Sciences-Talence (335222101) / SudocSudocFranceF

Rosetta Lander-Philae: Operations on comet 67P/Churyumov-Gerasimenko, Analysis of wake-up activities and final state

Philae, a comet Lander, part of the ESA Rosetta mission successfully landed on comet 67P/Churyumov- Gerasimenko on November 12th, 2014. After several (unplanned) bounces it performed a First Scientific Sequence (FSS), based on the energy stored in it's on board batteries. All ten instruments of the Philae payload have been operated at least once. Due to the fact that the original landing site was poorly illuminated, Philae went into hibernation on November 15th, but signals from the Lander were received again in June and July 2015. However, various attempts to re-establish reliable and stable communications links, failed. Analysis of the data gained during FSS, and during the contacts in June and July 2015 allows conclusions on the state of Philae. By now, images from the OSIRIS camera aboard the Rosetta Orbiter have allowed the identification of the exact position of Philae and its attitude, relative to the local surface terrain. The paper also gives an overview of the implications of Philae results for future engineering comet models, required particularly for the design of in-situ (landing) or sample return missions. Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta's Philae Lander is provided by a consortium led by DLR, MPS, CNES and ASI with additional contributions from Hungary, UK, Finland, Ireland and Austria

Rosetta Lander - Landing and operations on comet 67P/Churyumov-Gerasimenko

The Rosetta Lander Philae is part of the ESA Rosetta Mission which reached comet 67P/Churyumov–Gerasimenko after a 10 year cruise in August 2014. Since then, Rosetta has been studying both its nucleus and coma with instruments aboard the Orbiter. On November 12th, 2014 the Lander, Philae, was successfully delivered to the surface of the comet and operated for approximately 64 h after separation from the mother spacecraft. Since the active cold gas system aboard the Lander as well as the anchoring harpoons did not work, Philae bounced after the first touch-down at the planned landing site “Agilkia”. At the final landing site, “Abydos”, a modified First Scientific Sequence was performed. Due to the unexpectedly low illumination conditions and a lack of anchoring the sequence had to be adapted in order to minimize risk and maximize the scientific output. All ten instruments could be activated at least once, before Philae went into hibernation. In June 2015, the Lander contacted Rosetta again having survived successfully a long hibernation phase. This paper describes the Lander operations around separation, during descent and on the surface of the comet. We also address the partly successful attempts to re-establish contact with the Lander in June/July, when the internal temperature & power received were sufficient for Philae to become active again

PHILAE: Science scheduling and unknown context. leassons learned

Rosetta is an ambitious mission launched in March 2004 to study the nucleus as well as the coma of the comet 67P/Churyumov-Gerasimenko. It is composed of a space probe and the Philae Lander. The mission is a series of premieres: among others, first probe to escort a comet, first time a landing site is selected with a so short notice, first time a lander has landed on a comet nucleus. The space probe Rosetta reached the vicinity of the comet in spring 2014 when it has started to study Churyumov-Gerasimenko with remote sensing instruments. An intense observation phase followed to be able to select a landing site for the Lander. And in November 2014, at a distance of about 3 AU from the sun, Philae has reached its destination on the surface of the comet 67P. Once stabilized on the comet, the lander has performed its “First Science sequence”. Philae’s aim was to perform detailed and innovative in-situ experiments on the comet’s surface to characterize the nucleus by performing mechanical, chemical and physical investigations on the comet surface. The main contribution to the Rosetta lander by the French space agency (CNES) is the Science Operation and Navigation Centre (SONC) located in Toulouse. Among its tasks is the scheduling of the scientific activities of the 10 lander experiments and then to provide it to the Lander Control Centre (LCC) located in DLR Cologne. Nevertheless, the specific context of the Rosetta mission made this task even more complex if compared to usual spacecraft or landers: indeed the teams in charge of the Philae activity scheduling had to cope with huge constraints in term of energy, data management, asynchronous processes and co-activities or exclusions between instruments. In addition to these huge constraints it is important to note that the comet, its environment and the landing conditions remained unknown until the separation time and that the landing site was selected a short time before it had to take place and when the baseline operational sequence was already designed. This paper will explain the specific context of the Rosetta lander mission and all the constraints that the activity scheduling had to face to fulfil the scientific objectives specified for Philae. A specific tool was developed by CNES and used to design the complete sequence of activities on the comet with respect to all constraints. The baseline scenario designed this way will also be detailed to highlight the difficulties and challenges that the operational team had to face. A specific focus will be given on the landing site selection and the impacts on the scientific operations scheduling. Moreover the actual sequence performed on the comet will also be detailed and analysed to deduce the lessons that could be learned from such an unprecedented endeavour. Indeed as for every mission of exploration the flexibility concept was anticipated but had to face unexpected events

The Philae Lander: Science planning and operations

Rosetta is an ambitious mission launched in March 2004 to study comet 67P/Churyumov–Gerasimenko. It is composed of a space probe (Rosetta) and the Philae Lander. The mission is a series of premieres: among others, first probe to escort a comet, first time a landing site is selected with short turnaround time, first time a lander has landed on a comet nucleus. In November 2014, once stabilized on the comet, Philae has performed its “First Science Sequence”. Philae’s aim was to perform detailed and innovative in-situ experi- ments on the comet’s surface to characterize the nucleus by performing mechanical, chemical and physical investigations on the comet surface. The main contribution to the Rosetta lander by the French space agency (CNES) is the Science Operation and Navigation Center (SONC) located in Toulouse. Among its tasks is the scheduling of the scientific activities of the 10 lander experiments and then to provide it to the Lander Control Center (LCC) located in DLR Cologne. The teams in charge of the Philae activity scheduling had to cope with considerable constraints in term of energy, data management, asynchronous processes and co-activities or exclusions between instruments. Moreover the comet itself, its environment and the landing conditions remained unknown until separation time. The landing site was selected once the operational sequence was already designed. This paper will explain the specific context of the Rosetta lander mission and all the constraints that the lander activity scheduling had to face to fulfill the scientific objectives specified for Philae. A specific tool was developed by CNES and used to design the complete sequence of activities on the comet with respect to all constraints. The baseline scenario for the lander operation will also be detailed as well as the sequence performed on the comet to highlight the difficulties and challenges that the operational team faced

Rafts Promote Assembly and Atypical Targeting of a Nonenveloped Virus, Rotavirus, in Caco-2 Cells

Rotavirus follows an atypical pathway to the apical membrane of intestinal cells that bypasses the Golgi. The involvement of rafts in this process was explored here. VP4 is the most peripheral protein of the triple-layered structure of this nonenveloped virus. High proportions of VP4 associated with rafts within the cell as early as 3 h postinfection. In the meantime a significant part of VP4 was targeted to the Triton X-100-resistant microdomains of the apical membrane, suggesting that this protein possesses an autonomous signal for its targeting. At a later stage the other structural rotavirus proteins were also found in rafts within the cells together with NSP4, a nonstructural protein required for the final stage of virus assembly. Rafts purified from infected cells were shown to contain infectious particles. Finally purified VP4 and mature virus were shown to interact with cholesterol- and sphingolipid-enriched model lipid membranes that changed their phase preference from inverted hexagonal to lamellar structures. Together these results indicate that a direct interaction of VP4 with rafts promotes assembly and atypical targeting of rotavirus in intestinal cells

Rosetta Lander - Philae: Operations on 67P/Churyumov-Gerasimenki

Philae is a comet Lander, part of Rosetta which is a Cornerstone Mission of the ESA Horizon 2000 programme. Philae successfully landed on comet 67P/Churyumov-Gerasimenko on November 12th, 2014 and performed a First Scientific Sequence, based on the energy stored in it’s on board batteries. All ten instruments of the payload have been operated at least once. Due to the fact that the final landing site (after several bounces) was poorly illuminated, Philae went into hibernation on November 15th, and the teams hoped for a wake-up at closer heliocentric distance