Planetary Astronomy Late-morning Seminar for 2018-03-26

Series: Planetary Astronomy Late-morning Seminar
Date: Monday 26-Mar-2018
Time: 11:15-12:15
Location: ATL 1250
Speaker: Nilda Oklay/Jean-Baptiste Vincent (DLR)
Title: Large sub-surface volatile reservoirs of comet 67P / Evolution of cometary surfaces

Abstract (Oklay): Surface regions enriched in water ice are key to the sub-surface volatile reservoirs of comet 67P. Long-term high spatial resolution multispectral OSIRIS images of comet 67P allowed the detection and investigation of several water ice rich activity sources. Here, I will present detection of repeating activity from a large round basin (~700 m in diameter), which may indicate a large volatile reservoir on the big lobe of the comet. In this basin, I visually detected more than 30 transient activity events in which, several of those were repeating from the same source, which helps us to understand the sub-surface structure of the comet. Characterization of these events and associated source regions will be useful to put constrains to the cometary activity mechanisms that are in discussion. This has implications to the formation and evolution of comets. I will present the preliminary results of the characterization these events combining information from morphologic, spectroscopic and statistical analyses.

Abstract (Vincent): Cometary surfaces evolve a shorter time scale than other small bodies in the Solar System. Because changes are principally driven by the sublimation of volatiles in the subsurface, it is expected that most of the evolution takes place when the comet orbit brings the nucleus within the inner Solar System. Yet, this is not the whole picture.

Indeed, very few topographic changes have been observed on the cometary nuclei visited by spacecraft so far. For instance, only a handful of modifications were detected during the 2 years Rosetta orbited comet 67P. Thus, it is now postulated that the large scale topographic features are not a result of the erosion, bur rather formed very early in the history of the comet.

Yet comets still evolve, but perhaps at a different pace than initially thought. Recent development in mapping and image processing allow us to track changes on the surface at scales <10m. We found thousand of small surface modifications, from the opening of small pits, to jumping boulders, and expanding fracture networks. I will present some of these changes and discuss how they open a new window into cometary physics, at scales not investigated before.

For further information contact PALS coordinator Dr. Matthew Knight at or (301)-405-2629.


Special accommodations for individuals with disabilities can be made by calling (301) 405-3001. It would be appreciated if we are notified at least one week in advance.


Directions and information about parking can be found here.

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