Summertime, time for the Meteoritical Society’s annual meeting. This time, it’s in Brussels, BE.
PART I
Posting in parts is required, it’s a big meeting. Very big. (metsoc2024.brussels/programm/) This part will be Bennu-fest, since the timing works out. Base it on the sample capsule returning and secured last Autumn, initial description and cataloging, and primary distribution to project-affiliated scientists (those already on the team), plus work time, re-checking, and some writing. That means initial papers (not even full peer-reviewed Journal articles) were available in time for this meeting’s submission deadline.
And what papers- at least, what I can see. This meeting is in-person only, no virtual option:
– Returned Samples from Asteroids 1 – Monday, July 29, 8:30 AM
Russell S. S. Hamilton V. E. King A. J. et al. Mineralogy of Bennu: Evidence from Space and Laboratory #6397
Zega T. J. Prince B. S. Haenecour P. et al. Petrologic and Mineralogic Analysis of Bennu Aggregate Sample #6450
Thomas-Keprta K. Le L. Keller L. P. et al. Chondrules in Returned Samples from Asteroid Bennu #6417
Villeneuve J. Piani L. Marrocchi Y. et al. Oxygen Isotopic Composition of Olivine Grains in Bennu Samples #6333
Tkalcec B. J. DePauw E. Bazi B. et al. High Resolution SR-XRF Analysis of Ca-Rich Phases in Samples Collected from Asteroid Bennu #6107
Welten K. C. Nishiizumi K. Caffee M. W. et al. Surface Exposure History of the Regolith on Asteroid Bennu Based on Cosmogenic Radionuclides in OSIRIS-REx samples #6425
Thompson M. S. Keller L. P. Seifert L. B. et al. Analysis of Bennu Particles Extracted from the OSIRIS-REx Contact Pads #6377
Keller L. P. Seifert L. B. Melendez L. et al. Impact Melts and Microcraters in Bennu Aggregate Samples #6375
Sandford S. A. Gainsforth Z. Marcus M. A. et al. Relating Diffuse and Mineral Carbonates in Asteroid Bennu Samples Using X-Ray and Infrared Spectroscopy #6219
Eckley S. A. McCoy T. J. O’Neal E. W. et al. Textural Evidence of Fluid-Rock Interactions in Bennu Samples Revealed by X-Ray Computed Tomography Scanning #6071
Piani L. Marrocchi Y. Villeneuve J. et al. Hydrogen Isotopic Composition of Hydrous Minerals in Particles from Bennu #6080
Barnes J. J. Haenecour P. Smith L. R. et al. Characterization of Phosphates in Samples Returned from Asteroid Bennu #6240
Salge T. Russell S. S. King A. J. et al. Advancing SEM/EDS Microanalysis: Ultra High-Resolution Hyperspectral Imaging of Bennu Particles #6326
Rüfenacht M. Ek M. Meyer L. A. E. et al. Genetic Relationships and the Nucleosynthetic Heritage of the Asteroid Bennu #6158
– Returned Samples from Asteroids 2 – Monday, July 29, 2024, 1:30 PM
Haenecour P. Barnes J. J. Smith L. et al. Isotopically Anomalous Insoluble Organic Matter and Presolar Grains in Bennu Samples #6169
Grady M. M. Verchovsky A. B. Abernethy F. A. J. et al. Presolar Grains in Bennu: Constraints from C and N Isotopic Compositions #6188
Seifert L. B. Keller L. P. Nguyen A. N. et al. Transmission Electron Microscopy Study of Presolar Grains Preserved in Samples from Asteroid Bennu #6207
Singerling S. A. Brenker F. E. Tkalcec B. et al Nanoscale Studies of Sulfides and Carbonates in OSIRIS-REx Samples: What Can They Tell Us About Alteration on Bennu? #6131
Gainsforth Z. Sandford S. A. Marcus M. A. Dominguez G. Keller L. P. et al. Variable Iron Oxidation States in Asteroid Bennu Samples Returned by the OSIRIS-REx Spacecraft #6213
Prince B. S. Zega T. J. Connolly H. C. Lauretta D. S. Nanometer-Sized Fluid Inclusions in OSIRIS-REx Samples of Bennu #6224
Ray S. McCoy T. J. Corrigan C. M. et al. Texture and Mineralogy of Late-Stage Veins Containing Mg, Na-Phosphates in Bennu Samples #6233
Macke R. J. Ryan A. J. Ballouz R.-L. et al. Ideal-Gas Pycnometry on Pristine Bennu Specimens: Impossible Densities and Possible Explanations #6116
Manga V. R. Kontogiannis M. K. Zega T. J. et al. Thermodynamics-Driven Immiscible Fluids Under Microgravity: Interpreting Aqueous Processing and Microstructure Evolution of Bennu Samples #6111
Glavin D. P. McLain H. L. Parker E. T. et al. Extraterrestrial Amino Acids and Their Chemical Precursors in a Sample Returned from Asteroid (101955) Bennu #6070
Schmitt-Kopplin Ph. Liss M. Lucio M. et al. High Molecular Diversity and Structural Complexity of Soluble Organic Matter Revealed in Samples from Bennu’s Surface #6089
Clemett S. J. Thomas-Keprta K. L. Le L. et al. Organic Matter and Nanoglobules in Bennu Samples Revealed by Coordinated UV Fluorescence, SEM-EDX, and Two-Step Laser Mass Spectrometry #6422
Nguyen A. N. Clemett S. J. Thomas-Keprta K. et al. N-Rich Isotopically Anomalous Nanoglobules and Organic Matter in Bennu #6446
Dominguez G. Gainsforth Z. Marcus M. A. et al. X-Ray and Nano-Infrared Spectroscopy of Organic Matter in Asteroid Bennu Samples Returned by the OSIRIS-REx Spacecraft #6217
Did I say big? This is just one half of this year’s meeting, and the Bennu content culled from it. In it, we learn (assuming one hasn’t read the prior trickle of results) Bennu material is close to CI chondrites. Petrographically, it’s Type 1, with few (but nonzero) chondrules/AOAs and a ‘clay’ (phyllosilicate) matrix of serpentinite/smectite (often saponite). CI-like, type-1 material is the most pristine, least depleted stuff in the entire Solar System. Those few refractories (including unaltered olivines) indicate a complex history, mixing grains from different parts of the Solar System (which we could already see from OSIRIS-REx images). Noble-gas isotopes, versus oxygen and titanium isotopes, also show its mixed parentage.
Samples include surface particles, showing space weathering, and interior material, with a slightly different blend. One rock is, well, a rock, clearly over a centimeter in size; conversely there are no shortage of fines, including those in the contact pads. (Had the explicit sampling mechanism failed, the pads on the face of the sample container still grabbed surface powders.)
The Bennu surface had displayed carbonates- obvious, unmistakable veins of carbonates. Some of this is present at the micro-scale of these sample specimens, but no carbonate chunk made it into the collector. Lots of sulfur-ores, as expected from a CI-like body. That carbonate, and to a lesser extent sulfide, was deposited in multiple aqueous cycles- veins (mineral deposits in cracks) overlay and cross-cut older veins. Already announced were phosphates: Caa(PO4)bX and Mga(PO4)bX, with lesser Naa(PO4)bX. Phosphates come from- and are- water deposits, because the “X” is commonly -OH (less often, -F or other anions). Phosphates, too, show multiple ‘generations,’ indicating the hydrous timeline within Bennu was long and complicated.
Lower in amount but not importance: organics. We’ve known about space organics since well before OSIRIS-REx launched (that was one of the points of the mission), but what a mission result: pay dirt, including trapped water in the organics. Bennu samples include rich, diverse and sometimes, isotopically different organics. The diverse and aqueous organics indicate lack of, or protection from overheating; Bennu is ‘fresh.’ Got that? Bennu is rich in organics. And this includes nitrogen. Bennu regolith is fertile.
This fertility includes water, some of which may actually be in liquid form. Prince et al. are hedging, but they are fairly confident that- in just their allocated sample- they have found fluid inclusions (tiny rock pores) with various solvents inside, one of which is water. (Had they not been reasonably confident, they would not have even bothered writing and submitting.) LIQUID WATER. We’ll see if any other groups can confirm/correlate.
Overall, Bennu is fertile in the pedagogical sense, too. These two meeting sessions were completely Bennu presentations, or Bennu-dominant presentations. Session three breaks stride in including one Ryugu presentation… and even that one mentions Bennu as a comparable sample.
– Returned Samples from Asteroids 3 – Tuesday, July 30, 2024, 8:30 AM
Ishimaru K. Lauretta D. S. Connolly H. C. et al. Shape Analysis of Returned Sample Particles and Boulders of Asteroid Bennu #6184
Smith L. R. Haenecour P. Barnes J. J. et al. Pseudomorph Melt Spherules in Asteroid Bennu and Aqueously Altered Meteorites #6075
Crowther S. A. Gilmour J. D. Cowpe J. S. et al. Initial Xenon Isotopic Analysis of Individual Intermediate-Sized Particles from the OSIRIS-REx Sample of Asteroid Bennu #6277
Marty B. Zimmermann L. Füri E. et al. Noble Gases in Individual Particles from Bennu and Ryugu: Investigating the Origin of Garish Asteroidal Material #6428
Busemann H. Krietsch D. Maden C. et al. Noble Gases in Samples Returned from Asteroids Ryugu and Bennu #6453
Van den Neucker A. Hamann C. Bonato E. et al. The Structural and Spectroscopic Effects of Space Weathering of C-Type Asteroid Regolith Documented by Ryugu Sample A0112 #6413
Of what significance, then, do we place Bennu? Takir et al. and Nuth et al. draw the family inferences:
– Small Body Evolution and Planetary Differentiation 2 – Tuesday, July 30, 2024, 1:30 PM
Takir D. Emery J. P. Bottke W. F. et al. Origin Of Asteroid (101955) Bennu and Its Connection to the New Polana Family #6231
Nuth J. A. Ferguson F. T. Johnson N. M. Where Do Comets Go When Their Regoliths Become Desiccated? #6421
If you can’t be bothered to read Nuth et al.: Bennu, and perhaps Ryugu, etc. may be ‘asteroids’ formed from old comets.
– Chondrites 2: Carbonaceous and Related Chondrites – Thursday, August 1, 8:30 AM
Render J. Shollenberger Q. R. Brennecka G. A. et al. An Outer Solar System Origin of Bennu as Revealed by Its Bulk Chemical and Major Element Isotopic Compositions #6216
…and that’s before Render et al. Bennu material indicates, by multiple lines of evidence, that it (or at least, a proto-Bennu parent body) formed in the outer Solar System, obviously beyond the ‘snow line’ (the Solar System radius where it’s far enough, and cool enough, for water vapor to condense to ice, and settle into the new-forming bodies). That’s right: Centaurs aside (or not…?), Bennu and perhaps other carbonaceous chondrite ‘asteroids’ formed with ice, and are on some level cometary.
Oh, and there were posters too.
– Posters
Plummer J. Montoya M. Snead C. J. et al. OSIRIS-REx Sample Processing Tools and Techniques Utilized During Preliminary Examination #6174
Seifert L. B. Erickson T. Keller L. P. et al. Cathodoluminescence Microscopy and Spectroscopy of Apatite Grains in Bennu Samples #6208
Chaves L. C. Haenecour P. Barnes J. J. et al. Evaluating the Chemical Composition of Sulfides from Asteroid Bennu: Preparation for Sulfur Isotopic Analysis #6229
Harrison C. S. King A. J. Jones R. H. et al. Fe-Sulfides in Asteroid Bennu: Insights into Conditions of Aqueous Alteration #6409
Keller L. P. Seifert L. B. Thomas-Keprta K. et al. Transmission Electron Microscopy of Carbonaceous Matter in Bennu Aggregate Samples #6385
Nguyen A. N. Thomas-Keprta K. Le L. et al. The Presolar Grain Content of Morphologically Distinct Particles from Asteroid Bennu #6448
Righter K. Thomas-Keprta K. Le L. et al. Characterization of Bennu Particles for Morphologic, Textural, Lithologic, and Mineralogic Diversity #6235
Thompson M. S. Keller L. P. Thomas-Keprta K. et al. Evidence for Solar Wind Space Weathering in Samples from Asteroid Bennu #6389
Shirley K. A.* Bowles N. E. Laboratory Experiments to Recreate Asteroid Surface Thermal Conditions for Remote Sensing #6414
’til Part II… and ’til broader distribution of sample to non-OSIRIS-REx scientists…