The first images of the asteroid 243 Ida from Galileo show an irregular object measuring 56-kilometers by 24 kilometers by 21 kilometers. Its surface is rich in geologic features, including systems of grooves, blocks, chutes, albedo features, crater chains, and a full range of crater morphologies. The largest blocks may be distributed nonuniformly across the surface; lineaments and dark-floored craters also have preferential locations. Ida is interpreted to have a substantial regolith. The high crater density and size-frequency distribution (-3 differential power-law index) indicate a surface in equilibrium with saturated cratering. A minimum model crater age for Ida-and therefore for the Koronis family to which Ida belongs-is estimated at 1 billion years, older than expected.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1126/science.265.5178.1543 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
YOLO-Dynamic: A Detection Algorithm for Spaceborne Dynamic Objects.
Sensors (Basel)
November 2024
Opto-Electronics Engineering College, Changchun University of Science and Technology, Changchun 130022, China.
Ground-based detection of spaceborne dynamic objects, such as near-Earth asteroids and space debris, is essential for ensuring the safety of space operations. This paper presents YOLO-Dynamic, a novel detection algorithm aimed at addressing the limitations of existing models, particularly in complex environments and small-object detection. The proposed algorithm introduces two newly designed modules: the SC_Block_C2f and the LASF_Neck.
View Article and Find Full Text PDFTwo distinct populations of dark comets delineated by orbits and sizes.
Proc Natl Acad Sci U S A
December 2024
Institute for Astronomy, University of Hawaii, Honolulu, HI 96822.
Small bodies are capable of delivering essential prerequisites for the development of life, such as volatiles and organics, to the terrestrial planets. For example, empirical evidence suggests that water was delivered to the Earth by hydrated planetesimals from distant regions of the Solar System. Recently, several morphologically inactive near-Earth objects were reported to experience significant nongravitational accelerations inconsistent with radiation-based effects, and possibly explained by volatile-driven outgassing.
View Article and Find Full Text PDFDiagnostic ability of confocal scanning ophthalmoscope for the detection of concurrent retinal disease in eyes with asteroid hyalosis.
PLoS One
December 2024
Department of Ophthalmology, Biomedical Research Institute, Pusan National University Hospital, Pusan National University School of Medicine, Busan, South Korea.
Article Synopsis
- * Researchers analyzed medical records of 100 eyes with AH, finding that 76 had other retinal diseases; TC-cSO showed the best results, with 94% of images having minimal obscuration from asteroid bodies.
- * TC-cSO outperformed the other devices in accuracy (95%) and sensitivity (81%) for diagnosing retinal conditions, making it an effective alternative for screening when
The lack of floater perception in eyes with asteroid hyalosis and its direct implications on laser vitreolysis.
Int J Retina Vitreous
October 2024
Department of Ophthalmology, Rambam Health Care Campus, P.O.B 9602, Haifa, 31096, Israel.
Purpose: To present a novel optical model explaining why the vast majority of patients with Asteroid Hyalosis (AH) do not perceive any floaters. This changes our understanding of floater perception and undermines the operation mode of YAG laser vitreolysis.
Methods: Relying on a previously published model of floater perception based on astronomical equations of a solar eclipse, and on ultrasound images of the vitreous in three eyes with AH, we explain why such patients do not perceive floaters in spite of opaque bodies filling their entire vitreous, to the point of, in severe cases of AH, obscuring the fundus view during ophthalmoscopy.
The Ni isotopic composition of Ryugu reveals a common accretion region for carbonaceous chondrites.
Sci Adv
September 2024
Department of Natural History Sciences, Hokkaido University, Sapporo 001-0021, Japan.
The isotopic compositions of samples returned from Cb-type asteroid Ryugu and Ivuna-type (CI) chondrites are distinct from other carbonaceous chondrites, which has led to the suggestion that Ryugu/CI chondrites formed in a different region of the accretion disk, possibly around the orbits of Uranus and Neptune. We show that, like for Fe, Ryugu and CI chondrites also have indistinguishable Ni isotope anomalies, which differ from those of other carbonaceous chondrites. We propose that this unique Fe and Ni isotopic composition reflects different accretion efficiencies of small FeNi metal grains among the carbonaceous chondrite parent bodies.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!