E-Type Asteroid (2867) Steins as Imaged by OSIRIS on Board Rosetta

Science ◽  
2010 ◽  
Vol 327 (5962) ◽  
pp. 190-193 ◽  
Author(s):  
H. U. Keller ◽  
C. Barbieri ◽  
D. Koschny ◽  
P. Lamy ◽  
H. Rickman ◽  
...  
Keyword(s):  
Solid Rock ◽  
Direct Evidence ◽  
Imaging System ◽  
Main Belt ◽  
Rosetta Mission ◽  
Oblate Body ◽  
Spherical Diameter ◽  
Yorp Effect ◽  
Comet 67P ◽  
Rubble Pile

The European Space Agency’s Rosetta mission encountered the main-belt asteroid (2867) Steins while on its way to rendezvous with comet 67P/Churyumov-Gerasimenko. Images taken with the OSIRIS (optical, spectroscopic, and infrared remoteimaging system) cameras on board Rosetta show that Steins is an oblate body with an effective spherical diameter of 5.3 kilometers. Its surface does not show color variations. The morphology of Steins is dominated by linear faults and a large 2.1-kilometer-diameter crater near its south pole. Crater counts reveal a distinct lack of small craters. Steins is not solid rock but a rubble pile and has a conical appearance that is probably the result of reshaping due to Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) spin-up. The OSIRIS images constitute direct evidence for the YORP effect on a main-belt asteroid.

scholarly journals Surface evolution of the Anhur region on comet 67P/Churyumov-Gerasimenko from high-resolution OSIRIS images

2019 ◽  
Vol 630 ◽  
pp. A13 ◽  
Author(s):  
S. Fornasier ◽  
C. Feller ◽  
P. H. Hasselmann ◽  
M. A. Barucci ◽  
J. Sunshine ◽  
...  
Keyword(s):  
High Resolution ◽  
Imaging System ◽  
Morphological Changes ◽  
Surface Evolution ◽  
Water Ice ◽  
Narrow Angle ◽  
Highly Active ◽  
Rosetta Mission ◽  
High Resolution Images ◽  
Comet 67P

Context. The southern hemisphere of comet 67P/Churyumov-Gerasimenko (67P) became observable by the Rosetta mission in March 2015, a few months before cometary southern vernal equinox. The Anhur region in the southern part of the comet’s larger lobe was found to be highly eroded, enriched in volatiles, and highly active. Aims. We analyze high-resolution images of the Anhur region pre- and post-perihelion acquired by the OSIRIS imaging system on board the Rosetta mission. The Narrow Angle Camera is particularly useful for studying the evolution in Anhur in terms of morphological changes and color variations. Methods. Radiance factor images processed by the OSIRIS pipeline were coregistered, reprojected onto the 3D shape model of the comet, and corrected for the illumination conditions. Results. We find a number of morphological changes in the Anhur region that are related to formation of new scarps; removal of dust coatings; localized resurfacing in some areas, including boulders displacements; and vanishing structures, which implies localized mass loss that we estimate to be higher than 50 million kg. The strongest changes took place in and nearby the Anhur canyon-like structure, where significant dust cover was removed, an entire structure vanished, and many boulders were rearranged. All such changes are potentially associated with one of the most intense outbursts registered by Rosetta during its observations, which occurred one day before perihelion passage. Moreover, in the niche at the foot of a new observed scarp, we also see evidence of water ice exposure that persisted for at least six months. The abundance of water ice, evaluated from a linear mixing model, is relatively high (>20%). Our results confirm that the Anhur region is volatile-rich and probably is the area on 67P with the most pristine exposures near perihelion.

Ion energy and momentum flux near the cometopause of Comet 67P/Churyumov-Gerasimenko

2021 ◽  
Author(s):  
Hayley Williamson ◽  
Hans Nilsson ◽  
Anja Moslinger ◽  
Sofia Bergman ◽  
Gabriella Stenberg-Wieser
Keyword(s):  
Solar Wind ◽  
Complex Dynamics ◽  
Distribution Functions ◽  
Transitional Period ◽  
Ion Energy ◽  
Rosetta Mission ◽  
Before And After ◽  
Composition Analyzer ◽  
Energy And Momentum ◽  
Comet 67P

<p>Defined as the region where the plasma interaction region of a comet goes from being solar wind-dominated to cometary ion-dominated, the cometopause is a region of comingling plasmas and complex dynamics. The Rosetta mission orbited comet 67P/Churyumov-Gerasimenko for roughly two years. During this time, the cometopause was observed by the Ion Composition Analyzer (ICA), part of the Rosetta Plasma Consortium (RPC), before and after the spacecraft was in the solar wind ion cavity, defined as the region where no solar wind ions were measured. Data from ICA shows that solar wind and cometary ions have similar momentum and energy flux moments during this transitional period, indicating mass loading and deflection of the solar wind. We examine higher order moments and distribution functions for the solar wind and cometary species between December 2015 and March 2016. The behavior of the solar wind protons indicates that in many cases these protons are deflected in a sunward direction, while the cometary ions continue to move predominately antisunward. By studying the distribution functions of the protons during these time periods, it is possible to see a non-Maxwellian energy distribution. This can inform on the nature of the cometopause boundary and the energy transfer mechanisms at play in this region.</p>

scholarly journals The Rosetta Mission and the Chemistry of Organic Species in Comet 67P/Churyumov–Gerasimenko

Elements ◽  
2018 ◽  
Vol 14 (2) ◽  
pp. 95-100 ◽  
Author(s):  
Monica M. Grady ◽  
Ian P. Wright ◽  
Cécile Engrand ◽  
Sandra Siljeström
Keyword(s):  
Organic Species ◽  
Rosetta Mission ◽  
Comet 67P

scholarly journals Compressive strength of comet 67P/Churyumov-Gerasimenko derived from Philae surface contacts

2019 ◽  
Vol 630 ◽  
pp. A2 ◽  
Author(s):  
P. Heinisch ◽  
H.-U. Auster ◽  
B. Gundlach ◽  
J. Blum ◽  
C. Güttler ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Surface Material ◽  
Laboratory Measurements ◽  
Camera System ◽  
Upper Limit ◽  
Rosetta Mission ◽  
Ballistic Trajectory ◽  
Comet 67P ◽  
Insight Into ◽  
Impact Probe

Context. The landing and rebound of the Philae lander, which was part of the ESA Rosetta mission, enabled us to study the mechanical properties of the surface of comet 67P/Churyumov-Gerasimenko, because we could use Philae as an impact probe. Aims. The aim is to approximate the descent and rebound trajectory of the Philae lander and use this information to derive the compressive strength of the surface material from the different surface contacts and scratches created during the final touchdown. Combined with laboratory measurements, this can give an insight into what comets are made of and how they formed. Methods. We combined observations from the ROMAP magnetometer on board Philae with observations made by the Rosetta spacecraft, particularly by the OSIRIS camera system and the RPC-MAG magnetometer. Additionally, ballistic trajectory and collision modeling was performed. These results are placed in context using laboratory measurements of the compressibility of different materials. Results. It was possible to reconstruct possible trajectories of Philae and determine that a pressure of ~100 Pa is enough to compress the surface material up to a depth of ~20 cm. Considering all errors, the derived compressive strength shows little dependence on location, with an overall upper limit for the surface compressive strength of ~800 Pa.

scholarly journals The Rosetta Mission to Primitive Bodies of the Solar System

1994 ◽  
Vol 160 ◽  
pp. 381-394
Author(s):  
Yves Langevin
Keyword(s):  
Remote Sensing ◽  
Solar System ◽  
European Space Agency ◽  
Time Span ◽  
Main Belt ◽  
Space Agency ◽  
Rosetta Mission ◽  
One Year ◽  
Definition Of

The European Space Agency (ESA) has selected Rosetta as the next cornerstone mission, to be launched in 2003. The goal is to perfom one or more fly-bys to main belt asteroids, followed by a rendez-vous with an active comet. Advanced in situ analysis, both in the coma and on the surfaces of the nucleus, will be possible, as well as monitoring by remote sensing instruments of the nucleus and of the inner coma for a time span of more than one year, until perihelion. This paper outlines the scientific and technological choices done in the definition of the mission.

scholarly journals RPC-MIP observations at comet 67P/Churyumov-Gerasimenko explained by a model including a sheath and two populations of electrons

2019 ◽  
Vol 630 ◽  
pp. A41 ◽  
Author(s):  
G. Wattieaux ◽  
N. Gilet ◽  
P. Henri ◽  
X. Vallières ◽  
L. Bucciantini
Keyword(s):  
Collisionless Plasma ◽  
Plasma Sheath ◽  
Sheath Thickness ◽  
Mutual Impedance ◽  
Cometary Plasma ◽  
Rosetta Mission ◽  
Impedance Probe ◽  
First Time ◽  
Two Populations ◽  
Comet 67P

The response of the mutual impedance probe RPC-MIP on board Rosetta orbiter electrostatically modeled considering an unmagnetized and collisionless plasma with two Maxwellian electron populations. A vacuum sheath surrounding the probe was considered in our model in order to take the ion sheath into account that is located around the probe, which is immersed in the cometary plasma. For the first time, the simulated results are consistent with the data collected around comet 67P/Churyumov-Gerasimenko (67P), but strong discrepancies were identified with the previous simulations that neglected the plasma sheath around the probe. We studied the influence of the sheath thickness and of the electron populations. This work helps to better understand the initially unexpected responses of the mutual impedance probe that were acquired during the Rosetta mission. It suggests that two electron populations exist in the cometary plasma of 67P.

scholarly journals Multi-point galactic cosmic rays measurements between 1 and 4.5 AU over a full Solar cycle

2019 ◽  
Author(s):  
Thomas Honig ◽  
Olivier G. Witasse ◽  
Hugh Evans ◽  
Petteri Nieminen ◽  
Erik Kuulkers ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Radiation Environment ◽  
Radiation Data ◽  
Rosetta Mission ◽  
The Stability ◽  
Cross Calibration ◽  
Comet 67P

Abstract. The radiation data collected by the Standard Radiation Environment Monitor (SREM) aboard ESA missions INTEGRAl, ROSETTA, HERSCHEL, PLANCK and PROBA-1, and by the High Energy Neutron Detector (HEND) instrument aboard Mars Odyssey are analysed with an emphasis on characterising Galactic Cosmic Rays (GCRs) in the inner heliosphere. A cross-calibration between all sensors was performed for this study, which can also be used in subsequent works. We investigate the stability of the SREM detectors over long-term periods. The radiation data is compared qualitatively and quantitatively with the corresponding solar activity. Based on INTEGRAL and Rosetta SREM data, a GCR helioradial gradient of 2.96 %/AU is found between 1 and 4.5 AU. In addition, the data during the last phase of the Rosetta mission around comet 67P/Churyumov-Gerasimenko were studied in more detail. An unexpected and yet unexplained 8 % reduction of the Galactic Comic Ray flux measured by Rosetta SREM in the vicinity of the comet is noted.

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