ESA Science & Technology - Publication Archive
While landing on Titan, several instruments onboard Huygens acquired measurements that indicate the probe did not immediately come to rest. Detailed knowledge of the probe's motion can provide insight into the nature of Titan's surface. Combining accelerometer data from the Huygens Atmospheric Structure Instrument (HASI) and the Surface Science Package (SSP) with photometry data from the Descent Imager/Spectral Radiometer (DISR) we develop a quantitative model to describe motion of the probe, and its interaction with the surface. The most likely scenario is the following. Upon impact, Huygens created a 12 cm deep hole in the surface of Titan. It bounced back, out of the hole onto the flat surface, after which it commenced a 30-40 cm long slide in the southward direction. The slide ended with the probe out of balance, tilted in the direction of DISR by around 10°. The probe then wobbled back and forth five times in the north-south direction, during which it probably encountered a 1-2 cm sized pebble. The SSP provides evidence for movement up to 10 s after impact. This scenario puts the following constraints on the physical properties of the surface ... [Abstract abbreviated due to character limitations.]
Published online on 31 July 2012.
The 39th meeting of the Committee on Space Research (COSPAR) was held 14-22 July 2012 in Mysore, India.
This report to COSPAR on the scientific activities of the European Space Agency was written by members of the Directorate of Earth Observation, the Directorate of Human Spaceflight and Operations and the Directorate of Science and Robotic Exploration.
- Foreword by Jean-Jacques Dordain, Director General, ESA
- Earth Observation
- The Living Planet Programme
- The Earth Explorer Missions
- ERS and Envisat
- Human Spaceflight and Operations
- Overview: Columbus and ISS Facilities
- Funding Europe's ISS Research: ELIPS
- Research on the ISS
- Ongoing Research Using Other Platforms
- Projects under Development
- Science and Robotic Exploration
- Missions in Operation
- Missions in the Post-Operations and Archiving Phases
- Projects under Development
- Missions under Study
We have detected in Cassini data the signature of the periodic tidal stresses within Titan driven by the eccentricity (e = 0.028) of its 16-day orbit around Saturn. Precise measurements of the acceleration of the Cassini spacecraft during six close flybys between 2006 and 2011 have revealed that Titan responds to the variable tidal field exerted by Saturn with periodic changes of its quadrupole gravity, at about 4% of the static value. Two independent determinations of the corresponding degree-2 Love number yield k2 = 0.589 ± 0.150 and k2 = 0.637 ± 0.224 (2-sigma). Such a large response to the tidal field requires that Titan's interior is deformable over time scales of the orbital period, in a way that is consistent with a global ocean at depth.
This document describes the Payload of STE-QUEST, a mission in the Fundamental Physics domain conceived to test to high accuracy the different aspects of the Einstein Equivalence Principle. This document derives directly from the STE-QUEST Science Requirements Document and STE-QUEST Mission Requirements Document. It also integrates elements included in the STE-QUEST proposal (and associated reference documents), the STE-QUEST CDF Study and the STE-QUEST Instruments Mid-Term Review datapackages.
This document provides the baseline description of the payload, its instruments, supporting units and interfaces, as defined at the beginning of the STE-QUEST assessment study. It shall be consolidated as part of the study and shall be formally updated at the end of it. This is the first revision of the document, following the completion and closure of the Instruments mid-term Review held in May 2011.
JUpiter ICy moons Explorer (JUICE) is an ESA-led L-class mission of the ESA's Cosmic Vision 2015-25 Programme. It aims at a comprehensive exploration of the Jovian system with particular emphasis on Jupiter, its environment, and Galilean moons Ganymede, Europa and Callisto by investigating them as planetary bodies and potential habitats.
The Science Management Plan (SMP) describes the approach that will be implemented to ensure the fulfilment of the scientific objectives of the JUICE mission and to optimise its scientific return, with special emphasis on payload procurement, science operation and data management.
The Earth's bow shock is the most studied example of a collisionless shock in the solar system. It is also widely used to model or predict the behaviour at other astrophysical shock systems. Spacecraft observations, theoretical modelling and numerical simulations have led to a detailed understanding of the bow shock structure, the spatial organization of the components making up the shock interaction system, as well as fundamental shock processes such as particle heating and acceleration. In this paper we review the observations of accelerated ions at and upstream of the terrestrial bow shock and discuss the models and theories used to explain them. We describe the global morphology of the quasi-perpendicular and quasi-parallel shock regions and the foreshock. The acceleration processes for field-aligned beams and diffuse ion distribution types are discussed with connection to foreshock morphology and shock structure. The different possible mechanisms for extracting solar wind ions into the acceleration processes are also described. Despite several decades of study, there still remain some unsolved problems concerning ion acceleration at the bow shock, and we summarize these challenges.
Cataloguing the night sky is an essential part of astronomy. Before astronomers can investigate a celestial object, they must know where to find it. Without this knowledge, astronomers would wander helplessly in what Galileo once termed a 'dark labyrinth'.
ESA's Gaia mission will create a detailed map of this labyrinth, finding clues to the origin, structure and evolution of our home galaxy, the Milky Way.
- The discovery machine
- Stars as individuals and collectives
- Our Solar System and others
- How does Gaia work?
- Building Gaia
- The flood of data