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New Messages from Mercury

Posted By Bill Dunford

09-09-2013 10:12 CDT

Topics: pretty pictures, Mercury, MESSENGER

You and I can do something very few people in history have been able to do: tour the planet Mercury. In fact, just last week NASA made available a new trove of images from the MESSENGER spacecraft. The orbiter circles the planet every eight hours, carrying a sun-blocking heat shield on one side and a suite of powerful cameras and instruments on another. I've been exploring the new pictures, and here are a few that caught my eye. These were all taken during this calendar year. 

Mercury is sometimes just weird. I mean that in a good way, of course. The best example might be its famous water ice deposits, which defy the planet's searing heat by hiding in deep craters near the poles. Lit only by starlight, never directly by the sun, the floor of the crater Petronius is one such place. 

At the Edge of Darkness

NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

At the Edge of Darkness
The MESSENGER spacecraft returned this close view of Petronius Crater near the north pole of Mercury. The floor of the 36-km crater, which never sees the sun, hides deposits of water ice.

Sometimes the MESSENGER team commands the spacecraft to photograph the limb of Mercury at a highly oblique angle. These shots can reveal the shape the horizon, and are interesting just because they almost give the sensation of what it might be like to ride along with the orbiter as it buzzes over the surface of a harshly alien world. 

Flying Over Mercury

NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Flying Over Mercury
This shot of Mercury's limb from the MESSENGER orbiter gives a sense of what it might be like to fly over the landscape southwest of Debussy Crater.

Mercury is a gray planet. If you did fly along with MESSENGER you'd see a surface that appears mostly colorless to your eye. But that's not the whole truth. Varying kinds of minerals mark different parts of the landscape, depending on whether it formed in an eruption of lava, the impact of an asteroid, or some other process. Also, some terrain has been battered by space weather for longer than other places, depending on its age. All this leads to subtle color variations on the surface. MESSENGER's cameras can draw these color changes out by shooting through filters sensitive to different wavelengths of light. Combine these images into the red, green, and blue channels of an ordinary color picture, and suddenly Mercury's colors shine through. 


NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Bill Dunford

Mercury's spectacular Debussy crater as seen by the MESSENGER spacecraft. To the eye, the 80-km-wide crater would appear colored mostly in shades of gray. But by combining images taken through the orbiter's 996, 748, and 433 nm filters for red, green, and blue we can suddenly see the color differences that reveal the mineralogy of the surface.

It's uncertain low long our MESSENGER at Mercury will fly. Its budget has already run out (it continues to operate on a pay-as-you-go basis, pending a possible mission extension) and its fuel won't last forever. Meanwhile, it shows us--in striking detail--places that previous generations of explorers could only imagine.

See other posts from September 2013


Read more blog entries about: pretty pictures, Mercury, MESSENGER


Mike Martinez: 09/09/2013 01:23 CDT

What is the average depth of most craters on Mercury? Most seem rather shallow compared to our moon's craters. Also, could there still be an orbiting asteroid satellite circling around Mercury that we haven't detected yet?

Bill Dunford: 09/09/2013 06:59 CDT

Yes, a satellite is possible. The team conducted a search recently. If they found anything, it hasn't been announced. I don't know about the average depth, but the large craters around the north pole have depths up to 5k below "sea level".

Bob Ware: 09/10/2013 07:41 CDT

Thanks Bill. This is not the Mercury of my imagination in "my days" when I was a kid. Exploration, I love it!

Bill Dunford: 09/12/2013 07:32 CDT

Me too. New frontiers.

Messy: 09/12/2013 10:12 CDT

So how much fuel is left? I heard there wasn't much left anyway and they wanted the funds until the thing ran out of fuel.

Suzanne: 10/08/2013 04:19 CDT

Those are beautiful pictures. It is a shame the funding is out.

Brittany: 12/04/2013 07:43 CST

Beautiful pictures! Are we going to see any pictures of the actual ice that is deep in these craters? How much longer is the Messenger going to be able to last there? I'm sure we would all love to see more of these awesome pictures!

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