MESSENGER at Mercury (part II)

Two selected talks presented. I’m also going to float to other sessions.

Craters Craters Craters – C. Chapman presenting

Craters. Double-ringed craters. Craters with lumps in the middle. Craters with smooth basins in the middle. Craters overlapping craters.

Mercury is, put simply, littered with craters.

The come in chains. They come in clusters. They come in different periods of time.

In the heavily cratered areas on Mercury, there are two different populations that came in two different periods of time. (We know this from looking at how they overlap.)

2600 craters were measured in just 4 of MESSENGER’s new images!

Caloris Basin – S. Murchie presenting

Thought to be the youngest basin on Mercury. There is a main rim and ejecta and lineated plains surrounding it.

Basin originally formed in dark materials similar to highlands. Volcanism filled it in, but smaller (more recent) cratering re-exposed the darker material and also exposed deeper redder material. These colors only appear in color stretched images, but the non-stretched images are still fabulous. Click below to see hi-res image. Basin is circled.

Remarkably – this planet I learned in school was metal rich and very dense has low (e.g. not yet detected) surface iron according to the lack of 1micron iron line detection. This region was one of the best hopes for finding it because it dredges up deep material. They looked for the line, and the line didn’t look back.

all images credited to: NASA/Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington

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