Properties of Rubble-Pile Asteroid (101955) Bennu from OSIRIS-REx Imaging and Thermal Analysis

Establishing the abundance and physical properties of regolith and boulders on asteroids is crucial for understanding the formation and degradation mechanisms at work on their surfaces. Using images and thermal data from NASA's Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft, we show that asteroid (101955) Bennu's surface is globally rough, dense with boulders, and low in albedo. The number of boulders is surprising given Bennu's moderate thermal inertia, suggesting that simple models linking thermal inertia to particle size do not adequately capture the complexity relating these properties. At the same time, we find evidence for a wide range of particle sizes with distinct albedo characteristics. Our findings imply that ages of Bennu's surface particles span from the disruption of the asteroid's parent body (boulders) to recent in situ production (micrometre-scale particles)

The dynamic geophysical environment of (101955) Bennu based on OSIRIS-REx measurements

The top-shaped morphology characteristic of asteroid (101955) Bennu, often found among fast-spinning asteroids and binary asteroid primaries, may have contributed substantially to binary asteroid formation. Yet a detailed geophysical analysis of this morphology for a fast-spinning asteroid has not been possible prior to the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission. Combining the measured Bennu mass and shape obtained during the Preliminary Survey phase of the OSIRIS-REx mission, we find a notable transition in Bennu’s surface slopes within its rotational Roche lobe, defined as the region where material is energetically trapped to the surface. As the intersection of the rotational Roche lobe with Bennu’s surface has been most recently migrating towards its equator (given Bennu’s increasing spin rate), we infer that Bennu’s surface slopes have been changing across its surface within the last million years. We also find evidence for substantial density heterogeneity within this body, suggesting that its interior is a mixture of voids and boulders. The presence of such heterogeneity and Bennu’s top shape are consistent with spin-induced failure at some point in its past, although the manner of its failure cannot yet be determined. Future measurements by the OSIRIS-REx spacecraft will provide insight into and may resolve questions regarding the formation and evolution of Bennu’s top-shape morphology and its link to the formation of binary asteroids

Evidence for widespread hydrated minerals on asteroid (101955) Bennu

Early spectral data from the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission reveal evidence for abundant hydrated minerals on the surface of near-Earth asteroid (101955) Bennu in the form of a near-infrared absorption near 2.7 µm and thermal infrared spectral features that are most similar to those of aqueously altered CM-type carbonaceous chondrites. We observe these spectral features across the surface of Bennu, and there is no evidence of substantial rotational variability at the spatial scales of tens to hundreds of metres observed to date. In the visible and near-infrared (0.4 to 2.4 µm) Bennu’s spectrum appears featureless and with a blue (negative) slope, confirming previous ground-based observations. Bennu may represent a class of objects that could have brought volatiles and organic chemistry to Earth

F. Frabboni, Povera ma bella, la scuola fabbrica di futuro

La scuola della Riforma Gelmini descritta e analizzata da Franco Frabboni nelle sue carenze e nelle possibilità residue del sistema scolastico

G. Annacontini, Lo sguardo e la parola. Etnografia, cura e formazione

Il volume di G. Annacontini pone in evidenza la necessità e l’importanza di un approccio etnografico alla cura clinica che, travalicando l’idea stessa di cura e la concezione di salute, arrivi a costituirsi come ponte tra l’ambito medico e quello pedagogic

A. Criscenti Grassi (a cura di), Educare alla democrazia europea. Storia e ragioni del progetto unitario

Si tratta di un insieme di saggi sul tema della cittadinanza europea e dell'educazione alla democrazia, con riferimento costante alla dimensione pedagogica e al ruolo che questa può avere nella costruzione di un comune spirito europeo

Il mercato dei servizi d'ingegneria. 2002

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 , Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Riqualificazione del fronte-mare del litorale di S. Girolamo – Fesca

L’area di intervento è costituita dal tratto di litorale compreso tra il canale Lamasinata e la foce della lama Balice, sul quale si affacciano i quartieri residenziali di San Girolamo e Fesca, caratterizzati da mancanza di spazi pubblici e fenomeni di degrado del patrimonio edilizio ed ambientale. L’intervento oggetto del concorso è finalizzato ad incidere sul contesto paesaggisticoambientale del sito ma anche ad innescare processi di rivitalizzazione economica e sociale. Obiettivo del progetto è la configurazione di nuovi spazi pubblici del water-front, inteso come interfaccia terra-mare, al fine di ampliare e riqualificare le aree destinate alla balneazione pubblica con le relative strutture ed attrezzature complementar