Starship Asterisk*

Mercury's Vivaldi Crater from BepiColombo

Explanation: Why does this large crater on Mercury have two rings and a smooth floor? No one is sure. The unusual feature called Vivaldi Crater spans 215 kilometers and was imaged again in great detail by ESA's and JAXA's robotic BepiColombo spacecraft on a flyby earlier this month. A large circular feature on a rocky planet or moon is usually caused by either an impact by a small asteroid or a comet fragment, or a volcanic eruption. In the case of Vivaldi, it is possible that both occurred -- a heavy strike that caused a smooth internal lava flow. Double-ringed craters are rare, and the cause of the inner rings remains a topic of research. The speed-slowing gravity-assisted flyby of Mercury by BepiColombo was in preparation for the spacecraft entering orbit around the Solar System's innermost planet in 2026.

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Two different hits in approximately the same place?

This crater on Mercury is so like Schrodinger on the Moon. Indeed multi-ring craters on the Moon are quite common. They result from the more energetic impacts. I'm sure Chuck Wood could give a better explanation.
Peter Lloyd

Lasse H wrote: ↑Mon Sep 16, 2024 9:38 am Two different hits in approximately the same place?

Hmmm
https://solarsystem.nasa.gov/gltf_embed/2369/


Compare with the moon: Source:https://news.mit.edu/2016/retracing-ori ... -moon-1027

"According to the model, 3.8 billion years ago, a chunk of rock about 64 kilometers in size hit the moon at 54,000 kilometers per hour. The original crater that was created was up to 180 kilometers deep. This crater was not stable, the walls collapsed and warm rock flowed in from the side. This influx caused the crust above to collapse and the cliffs of the outer two rings, several kilometers high, were formed, the rear ring of which has a diameter of 930 kilometers.

According to the model, the third, inner ring was formed in a different way: When a cosmic impact occurs, the backlash often creates a central hill in the crater. In the case of the Orientale crater, this hill was too big and high to remain stable. It collapsed under its own gravity and thus formed the inner ring of the crater. "It was a really violent process," explains Johnson in a statement from his university. "These several kilometer-high cliffs and the inner ring all formed within minutes of the impact."
source: https://www.n-tv.de/wissen/Raetsel-um-M ... 90071.html

AVAO wrote: ↑Mon Sep 16, 2024 3:09 pm

Lasse H wrote: ↑Mon Sep 16, 2024 9:38 am Two different hits in approximately the same place?

Hmmm

Click to view full size image

https://solarsystem.nasa.gov/gltf_embed/2369/

...

What are you showing here? it almost looks like you reflected around the vertical midline, but not quite. Is this what the actual surface looks like (minus the blurry section in the middle)?

johnnydeep wrote: ↑Mon Sep 16, 2024 6:33 pm

AVAO wrote: ↑Mon Sep 16, 2024 3:09 pm

Lasse H wrote: ↑Mon Sep 16, 2024 9:38 am Two different hits in approximately the same place?

Hmmm

Click to view full size image

https://solarsystem.nasa.gov/gltf_embed/2369/

...

What are you showing here? it almost looks like you reflected around the vertical midline, but not quite. Is this what the actual surface looks like (minus the blurry section in the middle)?

Precisely. I just wanted to point out that a crater feature of practically the same size and identical appearance is very close by,
which surprised me. The blurred area in between probably comes from another mission and was added in order to be able to generate a complete 3D model.

bigg: https://upload.wikimedia.org/wikipedia/ ... bright.png
Source: Wikipedia (https://de.m.wikipedia.org/wiki/Datei:M ... bright.png)

AVAO wrote: ↑Mon Sep 16, 2024 7:14 pm

johnnydeep wrote: ↑Mon Sep 16, 2024 6:33 pm

AVAO wrote: ↑Mon Sep 16, 2024 3:09 pm

Hmmm

Click to view full size image

https://solarsystem.nasa.gov/gltf_embed/2369/

...

What are you showing here? it almost looks like you reflected around the vertical midline, but not quite. Is this what the actual surface looks like (minus the blurry section in the middle)?

Precisely. I just wanted to point out that a crater feature of practically the same size and identical appearance is very close by,
which surprised me. The blurred area in between probably comes from another mission and was added in order to be able to generate a complete 3D model.

Click to view full size image

bigg: https://upload.wikimedia.org/wikipedia/ ... bright.png
Source: Wikipedia (https://de.m.wikipedia.org/wiki/Datei:M ... bright.png)

Ok. Took me a while but I think I found your two crater features on one of the higher resolution versions of that image - did I get it right?:

Perhaps the impacting object had broken up shortly before striking Mercury, similarly as did that asteroid that struck Jupiter? Only the Mercury object broke into two pieces (one larger than the other) and they were not far apart from each other when striking the surface causing the 2 impact features?

Avalon wrote: ↑Tue Sep 17, 2024 2:19 am Perhaps the impacting object had broken up shortly before striking Mercury, similarly as did that asteroid that struck Jupiter? Only the Mercury object broke into two pieces (one larger than the other) and they were not far apart from each other when striking the surface causing the 2 impact features?

if an asteroid broke a few seconds before hitting the surface of a planet, the minutes of crater and lava creation would be like from one impact

if an asteroid broke beforehand and the two hits had a 10 minutes interval, the two craters will not be concentric

There is at least one other such crater with a double ring on Mercury crater Stoddart, see:

https://www.flickr.com/photos/europeans ... ateposted/

"The image reveals two ‘peak ring basins’, so-called due to their inner ring of peaks on an otherwise flattish floor. Vivaldi, named after the famous Italian composer Antonio Vivaldi (1678–1741) measures 210 km across. Stoddart, newly named because it was deemed interesting for BepiColombo scientists in the future, measures 155 km across."