Participation in the CONSERT instrument on Rosetta in order to inform the science team of up-to- date cometary nucleus models.

罗塞塔使命是欧洲航天局的基石使命之一，其主要目的是将航天器送入彗星核周围的轨道，并将着陆器放置在表面上。轨道器和着陆器都将携带几个独立的仪器。其中一个仪器，在轨道器和着陆器上都有组件，是COmet无线电波传输核探测实验（CONSERT）。CONSERT实验的主要科学目的是确定原子核内部深处的结构和组成。它将通过从轨道飞行器发射无线电波来实现这一点，该无线电波将穿过原子核并被着陆器（菲莱）接收。在接收到第一波后，着陆器将发射第二波，第二波将再次穿过原子核并被轨道器接收。从测量的传输时间和功率损耗，可以推断出内部的成分（折射率）以及内部反射的数量。这将被重复多次。设计这次使命时假设目标是彗星46 P/Wirtanen。发射的延迟意味着失去了飞往46 P/维尔塔宁彗星的机会，必须选择新的目标67 P/丘留莫夫-格拉西缅科彗星。对于许多仪器来说，这是一个微小的变化，但对于CONSERT来说，由于67 P/Churyumov-Gerasimenko是一颗比46 P/Wirtanen更大的彗星，这是相当重要的。至于选定频率的无线电波是否（现在不能改变）可以穿透彗星67 P/Churyumov-Gerasimenko核的较长弦（它也是相当细长的），尽管这只能在有更好的核内部模型可用时才能准确地确定。波是否会沿着沿着所有的弦穿透，对于CONSERT仪器，将着陆器放置在一些较短弦的末端附近将是有益的。然而，这引起了关于灰尘环境的问题，因为这样的着陆需要最深地穿透任何周围的灰尘。因此，CONSERT团队需要在相遇之前尽可能详细地了解67 P/Churyumov-Gerasimenko彗星的核心，以便最大限度地利用仪器的科学性。这是为了确定是否有可能沿沿着较长的弦杆进行发射，并估计在较短的弦杆之一端附近着陆的危险。此外，为了从测量数据中获得成分和结构，需要一些反演方法和建模。这也反过来需要最好的彗星核模型。这可以从直接观测67 P/Churyumov-Gerasimenko（当观测几何条件有利时）和研究类似轨道上类似大小的彗星中获得。关于彗星喷出的尘埃的信息可以从流星流的研究中获得。CONSERT团队作为一个整体并不具备足够的专业知识来进行这种建模。该提议者自90年代中期首次入选以来一直是CONSERT的联合研究员，而Levasser-Regourd教授是Co-I中仅有的两位有能力做到这一点的彗星/流星科学家。这一提议将使CONSERT小组能够尽可能了解彗星核的情况。目前并没有为完成上述任务所需的实际研究寻求资金，只是为提议者参加与CONSERT有关的讲习班和会议提供差旅费，以便CONSERT团队充分了解事态发展和影响。

The Rosetta mission is one of the cornerstone missions of the European Space Agency, it principal aim being to insert a spacecraft in orbit about a cometary nucleus and to place a lander on the surface. Both the orbiter and the lander would carry several independent instruments. One of the instruments, with components on both the orbiter and the lander is The COmet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT). The main scientific aim of the CONSERT experiment is to determine the structure and composition of the deep interior of the nucleus. It will do this by transmitting a radio wave from the orbiter which will pass through the nucleus and be received by the lande (Philae). On receiving the initial wave, the lander will transmit a second wave that will again pass through the nucleus and be received by the orbiter. From the measured time of transmission and the power loss, deductions can be made about the composition (refractive index) of the interior as well as the number of internal reflections. This will be repeated many times. The mission was designed on the assumption that the target was comet 46P/Wirtanen. Delay in the launch meant that the window for a flight to comet 46P/Wirtanen was lost and a new target, comet 67P/Churyumov-Gerasimenko, had to be selected. For many of the instruments, this was a minor change, but for CONSERT, as 67P/Churyumov-Gerasimenko is a larger comet than 46P/Wirtanen, it was rather more significant. It is very marginal as to whether or not the radio waves at the selected frequency (which can not now be changed) can penetrate all the way through the longer chords of the nucleus of comet 67P/Churyumov-Gerasimenko (which is also quite elongated), though this can only be accurately determined when better models of the interior of the nucleus are available.Whether or not waves will penetrate along all chords, for the CONSERT instruments, having the lander placed near the ends of some of the shorter chords would be beneficial. However, this raises problems regarding the dust environment, since such a landing requires the deepest penetration through any surrounding dust. Hence the CONSERT team require the most detailed knowledge possible regarding the nucleus of comet 67P/Churyumov-Gerasimenko before encounter in order to maximize the scientific from the instrument. This is required in order both to determine whether transmission along the longer chords is likely to be possible and to estimate the danger from landing near the end of one of the shorter chords. Also, in order to obtain the composition and structure from the measured data, some inversion methodology and modeling is required. This also in turn requires the best possible models of a comet nucleus. This can be obtained both from direct observations of 67P/Churyumov-Gerasimenko when the observing geometry is favourable and also from the study of comets of a similar size on similar orbits. Information regarding dust ejected from comets can be obtained from the study of meteor streams. The CONSERT team as a whole is not expert enough to carry out this modeling. The proposer, who has been a Co-Investigator on CONSERT since it was first selected in the mid 90's and Professor Levasser-Regourd are only two cometary/meteor scientists amongst the Co-I's capable of doing this. This proposal will allow the CONSERT team to be as well-informed as is possible regarding cometary nuclei. Funding is not being sought to carry out the actual research that is necessary to fulfill the above task, only travel costs to allow the proposer to attend CONSERT related workshops and meetings so that the CONSERT team is kept full aware of developments and implications.