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Mission: Hayabusa 2
Marcin600
post Feb 25 2023, 09:30 PM
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In Science Volume 379, Issue 6634, February 24, 2023:
„...In this issue, the results of laboratory analyses of the Ryugu samples are reported in five studies that investigate elemental abundances, isotope ratios, mineralogy, organic molecules, and more...” - https://www.science.org/toc/science/379/6634

Of these, 3 have open access:
An asteroid in the laboratory (an introductory text) - https://www.science.org/doi/10.1126/science.adh2109
Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites - https://www.science.org/doi/epdf/10.1126/science.abn7850
Noble gases and nitrogen in samples of asteroid Ryugu record its volatile sources and recent surface evolution - https://www.science.org/doi/epdf/10.1126/science.abo0431
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Marcin600
post Mar 12 2023, 06:17 PM
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The next two, very interestig articles from the February 24, 2023 Science issue, on organic matter in the Ryugu samples, are discussed in detail by JAXA - https://curation.isas.jaxa.jp/en/topics/23-02-24.html

1. The paper in Science: „Soluble organic molecules in samples of the carbonaceous asteroid (162173) Ryugu” - https://www.science.org/doi/10.1126/science.abn9033
Detailed overview: „Soluble Organic Matter (SOM) Team reveals organic molecule compositions in samples of asteroid Ryugu” - https://global.jaxa.jp/press/2023/02/20230224-1_e.html

2. The paper in Science: „Macromolecular organic matter in samples of the asteroid (162173) Ryugu” - https://www.science.org/doi/10.1126/science.abn9057
Detailed overview: „The dark Macromolecular organic matter of asteroid Ryugu” - https://global.jaxa.jp/press/2023/02/20230224-2_e.html
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Marcin600
post Apr 11 2023, 06:33 PM
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New paper on Ryugu samples:
"Variations of the surface characteristics of Ryugu returned samples" (open access):
https://earth-planets-space.springeropen.co...623-022-01754-8
https://earth-planets-space.springeropen.co...022-01754-8.pdf
https://curation.isas.jaxa.jp/en/topics/23-03-28.html
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Marcin600
post May 26 2023, 08:05 PM
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Occultation by asteroid 2001 CC21 has been observed
https://www.hayabusa2.jaxa.jp/topics/202303...CC21/index.html
https://www.hayabusa2.jaxa.jp/topics/20230314_2001_CC21/

[only in Japanese - here's a rough automatic translation of the excerpts]:

“… An occultation (stellar eclipse), in which (…) asteroid 2001 CC21 hides a star, was observed during an occultation observation campaign conducted (…) on March 5, 2023. During the observation we monitored the light of a 10.1-magnitude star in Camellia (TYC4082-00763-1) to see if the light from this star faded.

Observations were made from 20 points (…) However, the occultation was observed only in one place.

The time during which the star was hidden (occultation time) was 0.105 seconds. This is 449 m ± 12 m in length. (…) The size of CC21 is estimated to be about 700 m (…), is said to have a slightly elongated shape, and the short part [of the atseroid] may have been measured in this observation.

We also examined the orbital accuracy of CC21 as of July 2026, when Hayabusa2 spacecraft will fly by, and found that the positional error of CC21 is 47 km (1σ).

There are still opportunities for occultation observations by CC21, so we hope to observe a stellar eclipse in the next observation (…). It may also be possible to determine the shape of the asteroid by conducting more accurate occultation observations in the future…”
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Marcin600
post Jun 20 2023, 11:29 AM
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Here are published abstracts from the Hayabusa Symposium (latest from 2022):
https://curation.isas.jaxa.jp/symposium/abstract/index.html

2022: https://curation.isas.jaxa.jp/symposium/abs.../abs_2022.html#

e.g. some interesting articles:

The Aguas Zarcas breccia - similarities to surface features of C-type asteroids Ryugu and Bennu - https://curation.isas.jaxa.jp/symposium/abs...4_Kerraouch.pdf

Distinct ages and temperatures of aqueous activities recorded in Ryugu samples - https://curation.isas.jaxa.jp/symposium/abs...6_Nagashima.pdf

Elastic property of Ryugu samples collected at the second touch-down site - https://curation.isas.jaxa.jp/symposium/abs...-07_Onodera.pdf

Slickenside as a record of shock metamorphism on asteroid Ryugu - https://curation.isas.jaxa.jp/symposium/abs...08_Miyahara.pdf

Molecular descriptors for dictating the aqueous-alteration-induced organic decomposition in carbonaceous chondrites and return sample from Ryugu asteroid - https://curation.isas.jaxa.jp/symposium/abs...2/S11-05_Li.pdf
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Holder of the Tw...
post Nov 10 2023, 03:30 PM
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One more paper has come out on Hayabusa sample results, showing how liquid water in the parent asteroid shuffled some key isotopes around, particularly chromium isotopes.

Link: Article in online science dot org (open access)
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Marcin600
post Nov 24 2023, 03:00 AM
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New interesting results from the analysis of Ryugu samples (November 15, 2023):
„A newly revised estimation of bulk densities and examination of the shape of individual Ryugu grains” (open access)
https://earth-planets-space.springeropen.co...623-023-01904-6
https://curation.isas.jaxa.jp/en/topics/23-11-15.html

Some conclusions:
1. The average bulk density of 637 Ryugu grains, corresponding to 38 wt.% of the total returned samples (724 grains), is 1.79 ± 0.31 g/cm3.
2. The obtained bulk density is consistent with the density of a CI (Orgueil) chondrite: the average bulk density of Ryugu grains in the range of 1.57‒1.91 g/cm3 reported for Orgueil CI chondrites appears to support that Ryugu samples are similar to CI chondrites.
3. Microporosity of the examined Ryugu grains was roughly estimated to be 26‒31%, which is slightly higher than the latest data for the Orgueil CI chondrite and is close to the lowest value for the average Ryugu boulders.
4. 3D shape of Ryugu grains: the axial ratios (...) of Ryugu grains showed similar distribution to flying particles ejected from the Ryugu surface during sampling operations. Millimeter- to centimeter-sized Ryugu grains and pebbles may have a nearly uniform shape despite the returned sample show some shape deviation due to the mechanical scrape in the container.

The article also contains information on the "white grains" "decorating" these black stones: the white//transparent material, frequently found in Ryugu samples, was found to be complex carbonate-rich structures of crystals (minerals): dolomites (Ca-Mg carbonate) and breunnerites (Fe-bearing magnesite - Mg-Fe carbonate).


My own CI Orgueil meteorite fragment (0.007 g) - an "analogue" of Ryugu samples:
Attached thumbnail(s)
Attached Image
 
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