Rough Notes

<table style="margin: 0px auto;">

Center-align a HTML table - Stack Overflow

Comet 2019 LD2 (ATLAS)

“The newly discovered comet 2019 LD2 (ATLAS) is a Centaur, but is actively transitioning into a JFC. It is in the very earliest parts of this transition, and is the first time an object has been discovered prior to embarking on this transition”

- Jordan Steckloff, PSI Scientist

“Most significantly, our work found that LD2 is most likely a pristine comet. Although it has likely lost some supervolatile ices such as carbon dioxide ice (also known as dry ice) in the Outer Solar System beyond Jupiter, it is unlikely to have ever been in the inner Solar System (where Earth, the other rocky planets, and JFCs orbit), which is warm enough for water ice to sublime (‘evaporate’ from solid to gas),” Steckloff said. 

“This means that LD2 is a pristine comet, and presents a unique opportunity to observe how pristine JFCs behave as their water ice begins to sublime for the first time and drive comet activity. Moreover, this transition is likely to finish in only 40 years from now, which is a blink of an eye for astronomy.”

Steckloff said that scientists like to categorize things and put them into well-defined boxes. Part of modern planetary science is about understating why these categories exist in the first place (for example, we have active comets, inactive asteroids), and why some objects seem to fit in multiple boxes (Centaurs and Main Belt comets can look both asteroidal sometimes and cometary other times). 

https://www.psi.edu/news/steckloffcomet2019ld2%28atlas%29

https://iopscience.iop.org/article/10.3847/2041-8213/abc888

Similar bject - 29P/Schwassmann-Wachmann 1

Papers authored by Dr.Jessica Noviello

https://jessicanoviello.phd.sh/publications

She is an expert in Europa surface geology and geophysics, asteroid surface geology, and the Kuiper Belt object Haumea

Dimorphos’s material properties and estimates of crater size from the DART impact

https://www.hou.usra.edu/meetings/lpsc2023/pdf/2563.pdf

Angela Stickle et al, March 13, 2023 (LPSC)

No crater prediction in this, despite title mentioning 'crater size'

LPSC website advertised the session like this (see 8:55 AM) :

https://www.hou.usra.edu/meetings/lpsc2023/technical_program/?session_no=104

Dimorphos's Material Properties and Estimates of Crater Size from the DART Impact [#2563]

Crater grows, speed shifts / Ejecta shoots into space / Models tell us how.

------------------------

Lunar and Planetary Institute (http://www.lpi.usra.edu)

LPI video : https://www.youtube.com/watch?v=h7HJj-X-tyM

https://www.hou.usra.edu/meetings/lpsc2023/press-events/

Date : Mar 13, 2023

Dimorphos’s Material Properties and Estimates of Crater Size from the DART Impact

Presentation method : oral

Speaker : Angela Stickle

------------------------

Impact Simulations Provide Important Constraints On Dimorphos’s Material Properties And Estimates Of Crater Size From The Dart Impact

https://www.hou.usra.edu/meetings/acm2023/pdf/2541.pdf

Angela Stickle et al, June 2023 (Asteroids, Comets, Meteors Conference)

Crater prediction : From 40-60 m (min) to a larger basin-style reshaping of Dimorphos (max).

Extracts - No single simulation has yet, or is likely to without further data, uniquely explain every key observation from DART because many of Dimorphos’s properties remain currently unconstrained (subsurface structure, etc.) or are highly uncertain (e.g., density and mass of Dimorphos). 

For instance, the images of a rubble-strewn surface, abundant ejecta, and the magnitude of the period change rule out strength properties for Dimorphos similar to low-porosity competent rock (e.g., strength of 100s of MPa), which would have resulted in a β that is too low. Depending on the specific Dimorphos structure assumed, the setup of the rubble pile, and the material properties, simulations suggest that Dimorphos can have near-zero (< 10 Pa) to “moderately” weak nearsurface strengths (10s of kPa), and crater diameter could measure from 40-60 m to a larger basin-style reshaping of Dimorphos.

Summary : Following from the predictions of the DART IWG (Impact Modeling and 

Simulation Working Group), we will discuss how the observations following the DART impact, combined with the insights gained from impact simulations, can help reduce the uncertainty in Dimorphos’s material properties. 

Synthesizing results from a variety of simulations provides one of the best ways to evaluate potential “best-fit” properties of Dimorphos, and estimate ejecta mass and crater size. 

The constraints from the simulations will provide additional information regarding how data from Hera can further constrain Dimorphos’s material properties after it arrives at the Didymos system, and provide testable predictions for Hera observations (e.g., crater size).

-------------------------------

https://www.hou.usra.edu/meetings/lpsc2023/technical_program/?session_no=104

The shape of Dimorphos with relevance to binary asteroid formation

https://www.hou.usra.edu/meetings/lpsc2023/pdf/1671.pdf

Low strength of asteroid Dimorphos as demonstrated by the DART impact

https://www.hou.usra.edu/meetings/lpsc2023/pdf/2033.pdf

Sabina Raducan et al, March 13, 2023 (10:25 AM)

LPSC website advertised the session like this (see 10:25 AM) :

https://www.hou.usra.edu/meetings/lpsc2023/technical_program/?session_no=104

Low Strength of Asteroid Dimorphos as Demonstrated by the DART Impact [#2033]

(Dimorphos small and weak / DART impact, no crater made / But asteroid bent.)