Rosetta mission indicates comet 67P is not magnetic

Physics Today ◽  
2015 ◽  
Keyword(s):  
Rosetta Mission ◽  
Comet 67P

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 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.

scholarly journals Erratum: Evolution of the ion environment of comet 67P during the Rosetta mission as seen by RPC-ICA

2017 ◽  
Vol 469 (Suppl_2) ◽  
pp. S804-S804 ◽  
Author(s):  
Hans Nilsson ◽  
Gabriella Stenberg Wieser ◽  
Etienne Behar ◽  
Herbert Gunell ◽  
Martin Wieser ◽  
...  
Keyword(s):  
Rosetta Mission ◽  
Comet 67P

scholarly journals Plasma characterization at comet 67P between 2 and 4 AU from the Sun with the RPC-MIP instrument

2020 ◽  
Vol 638 ◽  
pp. A124
Author(s):  
Gaëtan Wattieaux ◽  
Pierre Henri ◽  
Nicolas Gilet ◽  
Xavier Vallières ◽  
Jan Deca
Keyword(s):  
Temperature Ratio ◽  
Electron Densities ◽  
Plasma Parameters ◽  
Mutual Impedance ◽  
Rosetta Mission ◽  
Fluctuation Range ◽  
Impedance Probe ◽  
Cold Electrons ◽  
Two Populations ◽  
Comet 67P

The plasma of comet 67P/Churyumov-Gerasimenko is analyzed based on the RPC-MIP mutual impedance probe data of the Rosetta mission. Numerical simulations of the RPC-MIP instrumental response considering two populations of electrons were fit on experimental responses acquired from January to September 2016 to extract the electron densities and temperatures. A time-tracking of the plasma parameters was performed, leading to the identification of a cold and a warm population of electrons during the period of interest. The respective densities and temperatures lie in the ranges [100; 1000] cm−3 and [0.05; 0.3] eV for the cold electrons and in the ranges [50; 500] cm−3 and [2; 10] eV for the warm electrons. Warm electrons most of the time made up between 10 and 30% of the whole population, while the temperature ratio between warm and cold electrons lay mostly between 30 and 70 during the period we studied. The fluctuation range of the plasma parameters, that is, the electron densities and temperatures, appears to have remained rather constant during the last nine months of the mission. We take the limitations of the instrument that are due to the experimental noise into account in our discussion of the results.

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