optics.org blog

« Just how good is Google? | Main | OIDA Photonics Integration Forum »

MESSENGER’s images of Mercury are back

By Jacqueline Hewett

Following my post on Monday about MESSENGER’s fly-by of Mercury, I’ve just gone back to the mission homepage and the first images are back. I was planning on adding a few to my previous post, but when you see the images, it seemed a shame not to give them a post of their own.

This first one was taken on 6 October by the wide angle camera (WAC) on the Mercury Dual Imaging System (MDIS) about 90 minutes after the spacecraft’s closest approach to Mercury. It was taken through a 430 nm filter and the image resolution is 5km per pixel. For reference, Mercury is about 4880 km in diameter.

Here is how NASA describes what you can see: “The bright crater just south of the centre of the image is Kuiper. For most of the terrain east of Kuiper, toward the edge of the planet, the departing images are the first spacecraft views of that portion of Mercury’s surface. A striking characteristic of this newly imaged area is the large pattern of rays that extend from the northern region of Mercury to regions south of Kuiper. This extensive ray system appears to emanate from a relatively young crater newly imaged by MESSENGER. This young, extensively rayed crater, along with the prominent rayed crater to the southeast of Kuiper, near the edge of the planet, were both seen in Earth-based radar images of Mercury but not previously imaged by spacecraft.”

This next close-up image of the surface was also taken by the WAC, this time through a 480 nm filter. The resolution is 330 meters per pixel and this time the image is just 340 km. The spacecraft altitude was 1800 km. The image was acquired just 9 minutes and 14 seconds after MESSENGER’s closest approach to Mercury, when the spacecraft was moving at 6.1 km/second.

This image is one in a sequence of 55: a five-frame mosaic with each frame in the mosaic acquired in by all 11 of the WAC filters. NASA says that this new MESSENGER image mosaic is the highest-resolution colour imaging ever acquired of any portion of Mercury’s surface.

The largest impact feature at the top of the image is about 133 km in diameter and is named Polygnotus. A second, comparably large crater at the top left of the image, is named Boethius.

I’m sure NASA will be adding more images to its MESSENGER science images gallery so its worth checking back to see what else gets posted over the coming days.

Posted by Jacqueline Hewett on October 8, 2008 3:37 PM | Permalink