ESA Science & Technology - Publication Archive
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MarcoPolo-R is a sample return mission to a primitive Near-Earth Asteroid (NEA) proposed in collaboration with NASA. It will rendezvous with a primitive NEA, scientifically characterize it at multiple scales, and return a unique sample to Earth unaltered by the atmospheric entry process or terrestrial weathering. MarcoPolo-R will return bulk samples (up to 2 kg) from an organic-rich binary asteroid to Earth for laboratory analyses, allowing us to: explore the origin of planetary materials and initial stages of habitable planet formation; identify and characterize the organics and volatiles in a primitive asteroid; understand the unique geomorphology, dynamics and evolution of a binary NEA. This project is based on the previous Marco Polo mission study, which was selected for the Assessment Phase of the first round of Cosmic Vision. Its scientific rationale was highly ranked by ESA committees and it was not selected only because the estimated cost was higher than the allotted amount for an M class mission. The cost of MarcoPolo-R will be reduced to within the ESA medium mission budget by collaboration with APL (John Hopkins University) and JPL in the NASA program for coordination with ESA's Cosmic Vision Call. The baseline target is a binary asteroid (175706) 1996 FG3, which offers a very efficient operational and technical mission profile. A binary target also provides enhanced science return. The choice of this target will allow new investigations to be performed more easily than at a single object, and also enables investigations of the fascinating geology and geophysics of asteroids that are impossible at a single object. Several launch windows have been identified in the time-span 2020-2024.
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Published online on 22 June 2011The discovery of a plume of water vapour and ice particles emerging from warm fractures ('tiger stripes') in Saturn's small, icy moon Enceladus raised the question of whether the plume emerges from a subsurface liquid source or from the decomposition of ice. Previous compositional analyses of particles injected by the plume into Saturn's diffuse E ring have already indicated the presence of liquid water, but the mechanisms driving the plume emission are still debated. Here we report an analysis of the composition of freshly ejected particles close to the sources. Salt-rich ice particles are found to dominate the total mass flux of ejected solids (more than 99 per cent) but they are depleted in the population escaping into Saturn's E ring. Ice grains containing organic compounds are found to be more abundant in dense parts of the plume. Whereas previous Cassini observations were compatible with a variety of plume formation mechanisms, these data eliminate or severely constrain non-liquid models and strongly imply that a salt-water reservoir with a large evaporating surface provides nearly all of the matter in the plume.
Summary of the study performed at ESA's Concurrent Design Facility (CDF) into the M-class mission Space-Time Explorer and QUantum Equivalence Principle Space Test (STE-QUEST).
Contents of the presentation:
- Study: goals, tasks, organization
- Drivers and constraints
- Configuration and payload accomodation
- Mission analysis
- Ground stations and operations
- Attitude and orbit control
- System design
- Risk, programmatics, cost
- Requirements review
Aims. IGR J18410-0535 was observed for 45 ks by XMM-Newton as part of a program aimed at studying the quiescent emission of supergiant fast X-ray transients and clarifying the origin of their peculiar X-ray variability.
Methods. We carried out an in-depth spectral and timing analysis of the XMM-Newton data.
Results. IGR J18410-0535 underwent a bright X-ray flare that started about 5 ks after the beginning of the observation and lasted for ~15 ks. Thanks to the capabilities of the instruments on-board XMM-Newton, the whole event could be followed in great detail. The results of our analysis provide strong convincing evidence that the flare was due to the accretion of matter from a massive clump onto the compact object hosted in this system.
Conclusions. By assuming that the clump is spherical and is moving at the same velocity as the homogeneous stellar wind, we estimate a mass and radius of Mcl~1.4×1022 g and Rcl~8×1011 cm. These are in qualitative agreement with values expected from theoretical calculations. No evidence for pulsations at ~4.7 s was found (we investigated coherent modulations in the range 3.5 ms-100 s). A reanalysis of the archival ASCA and Swift data of IGR J18410-0535, where such pulsations were previously detected, revealed that they were likely due to a statistical fluctuation and to an instrumental effect, respectively.