ZusammenfassungSeit der Entdeckung von Pluto hat sich das Bild des äußeren Planetensystems grundlegend gewandelt. Die Entdeckung und Erforschung des Kuiper‐Gürtels erlaubt Einblicke in die Entstehungsperiode des Sonnensystems. Die Bahnen und Eigenschaften der Körper in der Region jenseits von Neptun geben Hinweise auf die physikalisch‐chemischen und dynamischen Rahmenbedingungen während der Startphase des Planetensystems, ja sogar auf die Existenz eines neunten Planeten. Eine gezielte Suche nach Planet 9 hat begonnen.

Since the discovery of the first Transneptunian Objects (TNOs), a number of different dynamical classes of this primordial population have been identified. One of these classes, the Plutinos, is named after its most prominent member and populates the 2:3 resonance of Neptune. Despite the fact that some of the orbits of Plutinos are highly eccentric and can even overlap with that of Neptune, they represent the most densely populated, stable and therefore oldest population among resonant TNOs [Melita & Brunini 2000]. Their origin was first explained by [Malhotra 1995], showing that a radial outward movement of Neptune led to resonance capture. Escaping Plutinos can populate the Centaur region and even be a source of Jupiter Family Comets [di Sisto et al. 2010]. We present the physical characterization of 14 Plutinos and 1 Plutino candidate using PACS observations as part of the Herschel Open Time Key Programme ’TNOs are Cool’ [Muller et al. 2009]. This project was awarded some 370 h of Herschel observing time for the investigation of about 140 TNOs with known orbits. The goal is to characterize individual objects and the full sample using radiometric techniques in order to probe formation and evolution processes in the Solar System and to establish a benchmark for understanding the Solar System debris disk as well as extra-solar ones. The Plutino sample was selected solely on the basis of its Herschel observability and covers a wide range of dynamical properties in the Plutino population; it therefore serves as a probe for the whole population. Thermal-infrared data were taken using the PACS instrument in scan-map mode [Mueller et al. 2010]. In order to derive estimates of diameter and albedo, an asteroid thermal model was applied. Uncertainties in both parameters were estimated using a detailed Monte-Carlo analysis. A more sophisticated thermophysical model was applied to check the results and probe realistic ranges of thermal inertia. We discuss our results and compare them to already published results of Plutinos and other TNO subpopulations. [Malhotra 1995]: Malhotra, R. 1995, AJ, 110, 420 [Melita & Brunini 2000]: Melita, M. D. & Brunini, A. 2000, Icarus, 147, 205 [Muller et al. 2009]: Muller, T. G. and the ’TNOs are Cool’-Team 2009, EMP, 105, 209-219 [Muller et al. 2010]: Muller, T. G. and the ’TNOs are Cool’-Team 2010, A&A, 518, L146 [di Sisto et al. 2010]: di Sisto, R. P., Brunini, A. & de Elia, G. C. 2010, A&A, 519, A112+

We present the physical characterization of a set of 16 Plutinos, which were observed by the PACS instrument onboard Herschel. The characterization was performed using a thermal model and results in diameter and albedo estimations including uncertainties. We discuss our results and compare them to other TNO subpopulations.

We present results of the thermal lightcurve observations of TNOs Haumea, 2003VS2, 2003AZ84 and Varuna using the PACS [1] and SPIRE [2] instruments on the Herschel Space Observatory. These data were acquired as a part of the "TNOs are Cool" key programme [3], [4].

The are Cool: A Survey of the Trans-Neptunian Region project is a Herschel Open Time Key Program awarded some 370 h of Herschel observing time. The observations include PACS and SPIRE point-source photometry on about 140 trans-Neptunian objects with known orbits. The goal is to characterize the individual objects and the full sample using radiometric techniques, in order to probe formation and evolution processes in the Solar System and to establish a benchmark for understanding the Solar System debris disk as well as extra-solar ones. We present results on a set of TNOs which were selected for the Science Demonstration and early mission phases and report on progress in deriving effective sizes, geometric albedos, thermal characteristics, and our different approaches using thermal and thermophysical models.

Marco Polo is a mission to return a sample from a Near-Earth Object of primitive type (class C or D). It is foreseen as a collaborative effort between the Japanese Space Agency (JAXA) and the European Space Agency (ESA). Marco Polo is currently in a Phase-A study. This paper focuses on the scientific requirements provided to the industrial study consortia in Europe as well as the possible mission scenario at the target object in order to achieve the overall mission science objectives. The main scientific reasons for going to a Near-Earth Object are to understand the initial conditions and evolution history of the solar nebula, to understand how major events (e.g. agglomeration, heating) influence the history of planetesimals, whether primitive class objects contain presolar material, what the organics were in primitive materials, how organics could shed light on the origin of molecules necessary for life, and what the role of impacts by NEOs would be in the origin and evolution of life on Earth.

METIS is a mid-infrared instrument proposed for the European Extremely Large Telescope (E-ELT). It is designed to provide imaging and spectroscopic capabilities in the 3μm to 14μm region up to a spectral resolution of 100.000. Here the technical concept of METIS is described which has been developed based on an elaborated science case which is presented elsewhere in this conference. There are five main opto-mechanical modules all integrated into a common cryostat: The fore-optics is re-imaging the telescope focal plane into the cryostat, including a chopper, an optical de-rotator and an un-dispersed pupil stop. The imager module provides diffraction limited direct imaging, low-resolution grism spectroscopy, polarimetry and coronagraphy. The high resolution IFU spectrograph offers a spectral resolution of 100.000 for L- and M-band and optional 50.000 for the N-band. In addition to the WFS integrated into the E-ELT, there is a METIS internal on-axis WFS operating at visual wavelengths. Finally, a cold (and an external warm) calibration unit is providing all kinds of spatial and spectral calibrations capabilities. METIS is planned to be used at one of the direct Nasmyth foci available at the E-ELT. This recently finished Phase-A study carried out within the framework of the ESO sponsored E-ELT instrumentation studies has been performed by an international consortium with institutes from Germany, Netherlands, France, United Kingdom and Belgium.

The Jupiter family comet 73P/Schwassmann-Wachmann 3 has been widely observed since 1995 after a nucleus break-up event produced at least five components labeled 73P-A to E. During the 2006 appearance, two of them (B and C) showed very strong coma activity. Our R-filter imaging of 73P-B & C from 21 January to 25 May 2006 revealed the presence of fan-like structures in the comae of both components and evidence for further fragmentation events in component B. As of early April 2006, component C showed two jets emanating from the nucleus, with one continuously visible. Through a simulation of the orbital geometry we infer that the rotation axis of 73P-C has an inclination of 20° to the orbital plane and a longitude of 45° at perihelion. The coma activity of component B was highly variable, displaying signatures of at least 3 fragmentation events. The coma was characterized by the continuous presence of a jet roughly in sunward direction, starting from the beginning of May. The first fragmentation event of component B may have happened between April 16 and April 26, leading to the presence of at least 6 fragments detected in images of May 2. The second one happened on or shortly before May 8, the third one between May 18 and 24. For the rotation axis of 73P-B we infer an inclination of 5°–15° to the orbital plane and a longitude of 20°–30° at perihelion.

The collision of Deep Impact with comet 9P/Tempel 1 generated a bright cloud of dust which dissipated during several days after the impact. The brightness variations of this cloud and the changes of its position and shape are governed by the physical properties of the dust grains. We use a Monte Carlo model to describe the evolution of the post-impact dust plume. The results of our dynamical simulations are compared to the data obtained with FORS2, the FOcal Reducer and low dispersion Spectrograph for the VLT of the European Southern Observatory (ESO), to derive the particle size distribution and the total amount of material contained in the dust ejecta cloud.

Over one thousand objects have so far been discovered orbiting beyond Neptune. These trans-Neptunian objects (TNOs) represent the primitive remnants of the planetesimal disk from which the planets formed and are perhaps analogous to the unseen dust parent-bodies in debris disks observed around other main-sequence stars. The dynamical and physical properties of these bodies provide unique and important constraints on formation and evolution models of the Solar System. While the dynamical architecture in this region (also known as the Kuiper Belt) is becoming relatively clear, the physical properties of the objects are still largely unexplored. In particular, fundamental parameters such as size, albedo, density and thermal properties are difficult to measure. Measurements of thermal emission, which peaks at far-IR wavelengths, offer the best means available to determine the physical properties. While Spitzer has provided some results, notably revealing a large albedo diversity in this population, the increased sensitivity of Herschel and its superior wavelength coverage should permit profound advances in the field. Within our accepted project we propose to perform radiometric measurements of 139 objects, including 25 known multiple systems. When combined with measurements of the dust population beyond Neptune (e.g. from the New Horizons mission to Pluto), our results will provide a benchmark for understanding the Solar debris disk, and extra-solar ones as well.

Over one thousand objects have been discovered orbiting beyond Neptune. These trans-Neptunian objects (TNOs) represent the primitive remnants of the planetesimal disk from which the outer planets formed, and is an analog for unseen dust parent-bodies in debris disks observed around other main-sequence stars. The dynamical and physical properties of these bodies provide unique and important constraints on formation and evolution models of the outer Solar System. While the dynamical architecture in this region (also known as the Kuiper Belt) is becoming relatively clear, the physical properties of the objects are only beginning to be revealed. In particular, fundamental parameters such as size, albedo, density and thermal properties are difficult to measure. Measurements of their thermal emission, which peaks at far-IR wavelengths, offer the best means available to determine those physical properties. While Spitzer has provided the first results, notably revealing a large albedo diversity in this population, the increased sensitivity of Herschel and its wavelength coverage will permit profound advances in the field. Within our accepted project we propose to perform radiometric measurements of 139 objects, including 25 known multiple systems. This large sample will permit: (i) A determination of the size distribution of the large (> 200 km) objects, thought to have remained unchanged from the accretion phase. (ii) Systematic searches for correlations between size, albedo, and other physical and orbital parameters, diagnostic of formation and evolution processes. (iii) Determination of mass-density for at least 20 binary TNOs, diagnostic of nebular chemistry and interior structure. (iv) The first study of their thermophysical properties, including thermal inertia and surface emissivity. When combined with measurements of the dust population beyond Neptune (e.g. from the New Horizons mission to Pluto), our results will provide a benchmark for understanding the Solar debris disk, and extra-solar ones as well. We will present an overview of this project. Herschel will be the largest space telescope of its kind when launched (early 2009). Herschel's 3.5-metre diameter mirror will collect long-wavelength infrared radiation from some of the coolest and most distant objects in the Universe. Herschel will be the only space observatory to cover the spectral range from far-infrared to sub-millimetre wavelengths. Herschel's Photodetector Array Camera and Spectrometer (PACS) and its Spectral and Photometric Imaging Receiver (SPIRE) are perfectly suited for the characterisation of trans-Neptunian objects (TNOs), the observable targets of our own debris disk.

“Rosetta” is a Cornerstone Mission of the previous Horizon 2000 ESA Programme. Its goal is to rendezvous with comet 67/P Churyumov-Gerasimenko after a 10 years cruise and to study both its nucleus and coma through an orbiting spacecraft and a landed platform. The latter, named “Philae”, has been designed to land softly on the comet nucleus and is equipped with 10 scientific instruments to perform in-situ studies of the cometary material. Philae has been provided by an international consortium with participation of Germany (lead), France, Italy, UK, Finland, Ireland, Hungary and Austria.

1 ESO 2 Universidad Metropolitana de Ciencias de la Educacion, Santiago de Chile, Chile 3 Max-Planck-Institut fur Sonnensystemforschung, Katlenburg-Lindau, Germany 4 Institute of Astronomy, Sofia, Bulgaria 5 Universite de Liege, Belgium 6 CEA, Saclay, France 7 Vrije Universiteit Brussel, Belgium 8 Deutsches Zentrum fur Luft und Raumfahrt, Germany 9 Istituto Nazionale di Astrofisica (INAF) – Osservatorio di Arcetri, Italy * The ESO observations were the result of a worldwide scientific cooperation involving the following colleagues: Michael A’Hearn (University of Maryland, USA), Claude Arpigny (Universite de Liege, Belgium), Anita Cochran (McDonald Observatory USA), Catherine Delahodde (University of Florida, USA), Yanga Fernandez (University of Central Florida, USA), Damien Hutsemekers (Universite de Liege, Belgium), Hideyo Kawakita (Gunma Astronomical Observatory, Japan), Jorg Knollenberg (Deutsches Zentrum fur Luft und Raumfahrt, Germany), Ludmilla Kolokolova (University of Maryland, USA), Mike Kretlow (Max-Planck-Institut fur Sonnensystemforschung, Germany), Michael Kuppers (Max-Planck-Institut fur Sonnensystemforschung, Germany), Ekkehard Kuhrt (Deutsches Zentrumfur Luft und Raumfahrt, Germany), Luisa Lara (Instituto de Astrofisica de Canarias, Spain), Javier Licandro (Instituto de Astrofisica de Andalucia, Spain), Casey Lisse (The John Hopkins University/Applied Physics Laboratory, USA), Karen Meech (Universitiy of Hawaii, USA), Rita Schulz (ESTEC, the Netherlands), Gerhard Schwehm (ESTEC, the Netherlands), Michael Sterzik (ESO), Joachim A. Stuwe (Universiteit Leiden, the Netherlands), Isabelle Surdej (Universite de Liege, Belgium), Diane Wooden (NASA Ames Research Center, USA) and Jean-Marc Zucconi (Besancon, France). This article is a first summary of the observations done with ESO telescopes and instrumentation in the context of NASA’s Deep Impact (DI) space mission. The ESO observers* were part of an extremely active, communicative and thus successful worldwide network of observers. Through this network all information was freely exchanged and highlights are reported here as well.