ESA: Rosetta: Comet 67P/Churyumov–Gerasimenko

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Bern: Comet 67P is Younger than Previously Thought

Postby bystander » Thu Nov 10, 2016 5:23 pm

Chury is much younger than previously thought
University of Bern | 2016 Nov 09

Based on computer simulations, Astrophysicists at the University of Bern conclude that the comet Chury did not obtain its duck-like form during the formation of our solar system 4.5 billion years ago. Although it does contain primordial material, they are able to show that the comet in its present form is hardly more than a billion years old. ...

How primordial is the structure of comet 67P/C-G? Combined collisional
and dynamical models suggest a late formation
- M. Jutzi et al
Formation of bi-lobed shapes by sub-catastrophic collisions:
A late origin of comet 67P/C-G's structure
- M. Jutzi, W. Benz
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Make way for Comet 67P/Churyumov–Gerasimenko

Postby neufer » Thu Nov 10, 2016 10:31 pm

Art Neuendorffer

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NASA/JPL: The Many Faces of Rosetta's Comet 67P

Postby bystander » Wed Mar 22, 2017 2:56 pm

The Many Faces of Rosetta's Comet 67P
NASA | JPL-Caltech | Rosetta | 2017 Mar 21

Images returned from the European Space Agency's Rosetta mission indicate that during its most recent trip through the inner solar system, the surface of comet 67P/Churyumov-Gerasimenko was a very active place - full of growing fractures, collapsing cliffs and massive rolling boulders. Moving material buried some features on the comet's surface while exhuming others. ...

"As comets approach the sun, they go into overdrive and exhibit spectacular changes on their surface," said Ramy El-Maarry ... "This is something we were not able to really appreciate before the Rosetta mission, which gave us the chance to look at a comet in ultra-high resolution for more than two years."

Most comets orbit our sun in highly elliptical orbits that cause them to spend most of their time in the extremely cold outer solar system. When a comet approaches the inner solar system, the sun begins to warm the ice on and near the comet's surface. When the ice warms enough it can rapidly sublimate (turn directly from the solid to the vapor state). This sublimation process can occur with variable degrees of intensity and time-scales and cause the surface to change rapidly. Between August 2014 and September 2016, Rosetta orbited comet 67P during the comet's swing through the inner-solar system. ...

Before and After: Unique Changes Spotted on Rosetta’s Comet
ESA | Space Science | Rosetta | 2017 Mar 21

Surface changes on comet 67P/Churyumov-Gerasimenko suggest a more active past - M. Ramy El-Maarry et al

Collapsing Cliff Reveals Comet’s Interior
ESA | Space Science | Rosetta | 2017 Mar 21

The pristine interior of comet 67P revealed by the combined Aswan outburst and cliff collapse - M. Pajola et al
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Re: ESA: Rosetta: Comet 67P/Churyumov–Gerasimenko

Postby neufer » Wed Mar 22, 2017 3:18 pm

https://www.theguardian.com/lifeandstyl ... okens-vote wrote:
Monopoly: duck, penguin and T rex to replace boot, thimble and wheelbarrow
The Guardian, Friday 17 March 2017

<<Toy company Hasbro has replaced the boot, the thimble and the wheelbarrow with a Tyrannosaurus rex, a penguin and a rubber ducky in the latest version of its popular board game Monopoly.

More than 4.3 million voters from 146 countries weighed in on which tokens they wanted to see in future versions of the property-acquisition game, which is based on the real-life streets of Atlantic City. Hasbro announced the winners on Friday morning.

The existing scottish terrier, battleship, racing car, top hat and cat tokens will carry on.>>
Art Neuendorffer

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MPS: Rosetta Reveals Dust Jet from Comet 67P

Postby bystander » Thu Oct 26, 2017 3:46 pm

Rosetta Reveals Dust Jet
Max Planck Institute for Solar System Research | 2017 Oct 26

When comet 67P emitted a jet of dust into space in July 2016, five instruments from the Rosetta spacecraft were able to record the event. The scientific evaluation is now available.

The impressive jets of dust that comets emit into space during their journey around the Sun are not driven solely by the sublimation of frozen water. In some cases further processes augment the outbreaks. Possible scenarios include the release of pressurized gas stored below the surface or the conversion of one kind of frozen water into an energetically more favorable one. This is the result of a study published by a team of scientists headed by the Max Planck Institute for Solar System Research (MPS) in Germany analyzing a dust jet from Rosetta’s comet 67P/Chruyumov-Gerasimenko that occurred last year. The analysis, which has now been published in the journal Monthly Notices of the Royal Astronomical Society, compiles measurements of five instruments from ESA’s spacecraft Rosetta and was for the first time able to combine observations of the released dust as well as of the surface changes.


When the Sun rose over the Imhotep region of Rosetta’s comet on July 3, 2016, everything was just right: As the surface warmed and began to emit dust into space, Rosetta's trajectory led the probe right through the cloud. At the same time, the view of the scientific camera system OSIRIS coincidentally focused precisely on the surface region of the comet from which the fountain originated. A total of five instruments on board the probe were able to document the outburst in the following hours. ...

Evidence of sub-surface energy storage in comet 67P from the outburst of 2016 July 03 - J. Agarwal et al
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RAS: "Missing Link" in Planet Formation Revealed

Postby MargaritaMc » Fri Oct 27, 2017 12:03 pm

https://www.ras.org.uk/news-and-press/3059-comet-mission-reveals-missing-link-in-our-understanding-of-planet-formation

RAS: Comet Mission Reveals "Missing Link" in our Understanding of Planet Formation


The missing link in our understanding of planet formation has been revealed by the first ever spacecraft to orbit and land on a comet, say German scientists. The study is published in a recent edition of the journal Monthly Notices of the Royal Astronmical Society.

Based on the results of the Rosetta mission, Blum and colleagues conclude that comet 67P is composed of millimetre-sized dust pebbles. It is assumed that the pebbles inside the comet consist of a mixture of dust and ice (light blue spheres in the image) and only the uppermost layers, which are exposed to direct sunlight, do not contain ice (dark grey spheres).

Credit: Maya Krause, TU Braunschweig

A research team led by Jürgen Blum (Technische Universität Braunschweig, Germany) have analysed data from the historicRosetta mission to uncover how comet 67P/Churyumov-Gerasimenko, or "Chury" for short, came into existence more than four and a half billion years ago.

Understanding the evolution of our solar system and its planets was one of the main objectives of the Rosetta mission to comet 67P/Churyumov-Gerasimenko. For Jürgen Blum and his international team it was worth it, because results from the various Rosetta and Philae instruments have revealed that only one out of many proposed models can explain their observations. Comet 67P consists of 'dust pebbles' ranging between millimetres and centimetres in size.

Professor Blum explains the implications of the team's observations "Our results show that only a single model for the formation of larger solid bodies in the young solar system may be considered for Chury. According to this formation model, 'dust pebbles' are concentrated so strongly by an instability in the solar nebula that their joint gravitational force ultimately leads to a collapse."

This process forms the missing link between the well-established formation of 'dust pebbles' ('planetary building blocks' formed in the solar nebula by sticking collisions between dust and ice particles) and the gravitational accretion of planetesimals into planets, which scientists have pondered over for years.

"Although it sounds very dramatic" Blum continues, "it's actually a gentle process in which the dust agglomerates are not destroyed, but are combined into a larger body with an even greater gravitational attraction - the accumulation of the dust agglomerates into a coherent body is virtually the birth of the comet." Due to the relatively small mass of comet 67P, the pebbles survived intact until today, allowing scientists to confirm the hypothesis for the first time.

In fact, the pebble-collapse formation model can explain many observed properties of comet 67P, for instance its high porosity and how much gas is escaping from inside. "Now all phases in the planet-formation model have been established", concludes Blum.


Evidence for the formation of comet 67P/Churyumov-Gerasimenko through gravitational collapse of a bound clump of pebbles
Jürgen Blum et al

Monthly Notices of the Royal Astronomical Society, stx 2741,
https://doi.org/10.1093/mnras/stx2741
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MPS: Rosetta: A Comet’s List of Ingredients

Postby bystander » Sat Dec 02, 2017 3:01 pm

Rosetta: A Comet’s List of Ingredients
Max Planck Institute for Solar System Research | 2017 Dec 01

For the first time, researchers from the COSIMA team present a quantitative analysis of which chemical elements make up comet 67P/Churyumov-Gerasimenko.

The dust that comet 67P/Churyumov-Gerasimenko emits into space consists to about one half of organic molecules. The dust belongs to the most pristine and carbon-rich material known in our solar system and has hardly changed since its birth. These results of the COSIMA team are published today in the journal Monthly Notices of the Royal Astronomical Society. COSIMA is an instrument onboard the Rosetta spacecraft, which investigated comet 67P/Churyumov-Gerasimenko from August 2014 to September 2016. In their current study, the involved researchers including scientists from the Max Planck Institute for Solar System Research (MPS) analyze as comprehensively as ever before, what chemical elements constitute cometary dust.

Carbon-Rich Dust in Comet 67P/Churyumov-Gerasimenko Measured by COSIMA/Rosetta - Anaïs Bardyn et al
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