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.

Chemical highlights from the Rosetta mission

2017 ◽  
Vol 13 (S332) ◽  
pp. 153-162 ◽  
Author(s):  
Kathrin Altwegg ◽  
Keyword(s):  
Solar System ◽  
Solar Nebula ◽  
Oort Cloud ◽  
Origin And Evolution ◽  
Rosetta Mission ◽  
Show Evidence ◽  
Isotopic Abundances ◽  
Dust Grain ◽  
Comet 67P ◽  
Insight Into

AbstractThe overall goal of the ESA Rosetta mission was to help decipher the origin and evolution of our solar system. Looking at the chemical composition of comet 67P/Churyumov-Gerasimenko is one way of doing this. The amount of very volatile species found and the insight into their isotopic abundances show that at least some presolar ice has survived the formation of the solar system. It shows that the solar nebula was not homogenized in the region where comets formed. The D/H ratio in water furthermore indicates that Jupiter family comets and Oort cloud comets probably formed in the same regions and their difference is then purely due to their different dynamical history. The organics found in 67P are very diverse, with abundant CH- and CHO- bearing species. Sulphur bearing species like S3 and S4 and others show evidence of dust grain chemistry in molecular clouds.

In-situ detection of cometary cyanogen (NCCN)

2020 ◽  
Author(s):  
Nora Hänni ◽  
Kathrin Altwegg ◽  
Boris Pestoni ◽  
Martin Rubin ◽  
Isaac Schroeder ◽  
...  
Keyword(s):  
Production Rate ◽  
Hydrogen Cyanide ◽  
Space Science ◽  
Upper Limit ◽  
Rosetta Mission ◽  
Long Time ◽  
Double Focusing ◽  
In Situ Detection ◽  
Comet 67P

<p>For a long time it was thought that the cyano (CN) radical, observed remotely many times in various stellar and interstellar environments, is exclusively a photodissociation product of hydrogen cyanide (HCN). Bockelée-Morvan et al. (1984) first questioned this notion based on remote observations of comet IRAS-Araki-Alcock. They reported an upper limit for the HCN production rate which was smaller than the CN production rate previously derived by A’Hearn et al. (1983). Even today, this discrepancy observed for some comets is not resolved although many alternative parents have been suggested. Among the volatile candidates, cyanogen (NCCN), cyanoacetylene (HC<sub>3</sub>N) and acetonitrile (CH<sub>3</sub>CN), according to Fray et al. (2005), are the most promising ones. While cyanoacetylene and acetonitrile are known to be present in trace amounts in comets, as reported for comet Hale-Bopp by Bockelée-Morvan et al. (2000) and for comet 67P/Churyumov-Gerasimenko by Le Roy et al. (2015) and Rubin et al. (2019), the abundance of cyanogen in comets is unknown. Altwegg et al. (2019) were the first to mention its detection in the inner coma of comet 67P/Churyumov-Gerasimenko, target of ESA’s Rosetta mission.</p> <p>In this work, we track the signatures of cyanogen in the ROSINA/DFMS (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/ Double Focusing Mass Spectrometer; Balsiger et al. (2007)) data, collected during the Rosetta mission phase. We derive abundances relative to water for three distinct periods, indicating that cyanogen is not abundant enough to explain the CN production in comet 67P together with HCN. Our findings are consistent with the non-detection of cyanogen in the interstellar medium.</p> <p> </p> <p>A’Hearn M.F., Millis R.L., 1983, IAU Circ., 3802</p> <p>Altwegg K., Balsiger H., Fuselier S.A., 2019, Annu. Rev. Astron. Astrophys., 57, 113–55</p> <p>Balsiger H. et al., 2007, Space Science Reviews, 128, 745-801</p> <p>Bockelée-Morvan D., Crovisier J., Baudry A., Despois D., Perault M., Irvine W.M., Schloerb F.P., Swade D., 1984, Astron. Astrophys., 141, 411-418</p> <p>Bockelée-Morvan et al., 2000, Astron. Astrophys., 353, 1101–1114.</p> <p>Fray N., Bénilan Y., Cottin H., Gazeau M.-C., Crovisier J., 2005, Planetary and Space Science, 53, 1243-1262</p> <p>Le Roy L. et al., 2015, Astron. Astrophys., 583, A1</p> <p>Rubin M. et al., 2019, MNRAS, 489, 594-607</p>

scholarly journals Laboratory measurements to interpret dust polarimetric observations and in-situ radar studies. Implications for the Rosetta mission.

2015 ◽  
Vol 11 (A29A) ◽  
Author(s):  
A.-Ch. Levasseur-Regourd ◽  
Yann Brouet ◽  
Edith Hadamcik
Keyword(s):  
Laboratory Studies ◽  
Laboratory Measurements ◽  
Scattering Media ◽  
Astronomical Observations ◽  
Dust Clouds ◽  
Rosetta Mission ◽  
Recent Developments ◽  
Solar System Bodies ◽  
Comet 67P

Polarimetric astronomical observations on dust clouds and regolithic surfaces require laboratory simulations on samples to provide clues to properties of the scattering media. Similarly, in-situ radar investigations of Solar System bodies require laboratory studies to infer the physical properties of their interiors. Recent developments are illustrated by analyses of comet 67P/Churyumov-Gerasimeko (C-G) remote observations and in-situ studies from Rosetta mission.

scholarly journals Setting an Upper Limit on the Myoglobin Iron(IV)Hydroxide pKa: Insight into Axial Ligand Tuning in Heme Protein Catalysis

2014 ◽  
Vol 136 (25) ◽  
pp. 9124-9131 ◽  
Author(s):  
Timothy H. Yosca ◽  
Rachel K. Behan ◽  
Courtney M. Krest ◽  
Elizabeth L. Onderko ◽  
Matthew C. Langston ◽  
...  
Keyword(s):  
Heme Protein ◽  
Axial Ligand ◽  
Upper Limit ◽  
Insight Into ◽  
Protein Catalysis

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 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.

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