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Mercury’s previously unseen side

Wolverine

Centered and One
Wolverine
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How sweet is this?

When Mariner 10 flew past Mercury three times in 1974 and 1975, the same hemisphere was in sunlight during each encounter. As a consequence, Mariner 10 was able to image less than half the planet. Planetary scientists have wondered for more than 30 years about what spacecraft images might reveal about the hemisphere of Mercury that Mariner 10 never viewed.

On January 14, 2008, the MESSENGER spacecraft observed about half of the hemisphere missed by Mariner 10. This image was snapped by the Wide Angle Camera, part of the Mercury Dual Imaging System (MDIS) instrument, about 80 minutes after MESSENGER's closest approach to Mercury (2:04 pm EST), when the spacecraft was at a distance of about 27,000 kilometers (about 17,000 miles)
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It's wild to take in, especially considering we've assembled complete surface maps of so many other, more distant bodies in the solar system (even Jovian and Saturnian moons come to mind) before being in position to have a more complete view of Mercury. After all this time we can finally get more familiar with the innermost planet. More flyby imagery will be posted soon I'm sure.

Mariner 10 imagery is available here.
 
Awesome stuff.

When Mariner 10 flew past Mercury three times in 1974 and 1975, the same hemisphere was in sunlight during each encounter.
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This confused me, since I learned that mercury was tidal locked to the sun. So wiki'd mercury and found out that it rotates three times every two mercurial years ... this new discovery happened in 1965, several years before I was born. Woot education.

Walt
 
The face on Mars was only the beginning. Wait until we see...the Bum on Mercury!

Athon
 
Yesterday, the NASA site was saying that it would be a week before the images would be released. The Featured Release pic today was after Messenger's closest approach. I'll be eagerly awaiting the closeups from 124 miles - sure to be extraordinary!

Another fascinating aspect of this mission is the extreme heat tech they are using to protect Messenger from the Sun and the reflected radiation from Mercury's surface - behind the heat shields, Messenger is supposed to stay pretty close to room temperature. That's some trick! :cool:
 
Awesome. Mercury is always down in the "grass" by the horizon, in the bad seeing, because it's so close to the Sun. I've looked at it a few times, but never really seen much as a result; generally there's atmospheric refraction that gives false color even in a reflector. I suppose you could try bagging it during full daylight, but the problem is that the slightest mistake and you're instantly blind (from the Sun, because it's so close). Still, an eyeball view of Mercury on the horizon following the already-set Sun down, or preceding the not-yet-risen Sun up, before or after a night of good astronomy is my second favorite sight, and I always bag it if I can; my favorite is the earthshine on the dark part of the crescent Moon. Somewhere I have the earthshine on the crescent moon, next to the Beehive. One of my favorite shots, and one you can get during the Spring and early Summer.

BTW, the common conception that you can't do astronomy during the day (except solar) is wrong; the planets are generally bright enough to see. I was first shown Jupiter during the day six or seven years ago, and when there's a good planet up to look at, I generally put the telescope on it while I break my equipment down and pack it up after sunrise after a star party. Surprisingly, you can even get good seeing, although the contrast isn't anything to write home about (blue cast over everything from the scattered light). So don't think I'm crazy when I say we might be able to find out more about Mercury by doing astronomy during the day when it's high in the sky, where the seeing might be good.
 
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Fidelio said:
Ya seen it here first:

Hoaglandesque post.

The Cross on Mercury
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Bah, too mundane for Hoagie. :p

Any bets though on how long it'll be before someone claims to see alien artifacts? RCH did so with the very first batch of imagery from Mars Reconnaissance Orbiter.
 
gdtbiker said:
Another fascinating aspect of this mission is the extreme heat tech they are using to protect Messenger from the Sun and the reflected radiation from Mercury's surface - behind the heat shields, Messenger is supposed to stay pretty close to room temperature. That's some trick! :cool:
Click to expand...

In space, you don't have convection, and you obviously don't have conduction except from one part of the craft to another), so the only variable to control is radiation, done with reflective foil and sometimes "umbrellas". The trick is to balance the radiation coming in and that going out to keep the electronics toasty. Sometimes (and particularly in this case) the trick is to provide enough dull black surface facing away from the sun to radiate off the excess heat generated by the electronics.
 
OK, first off, here's my blog post on the one image released so far.

Second, the images from Mariner 10 only showed one face because of the way the orbital mechanics worked out for the two flybys in 1974. It wound up passing the planet when it was in the same "phase", showing the same face to the Sun. Irritating, but better than nothing.

That's what makes this new image (and the ones to follow) so sweet: we're already seeing, in high-res, parts of Mercury never seen clearly before. After looking at the image I was intrigued by one crater, but couldn't find it in any of the literature online. After a few minutes, I realized that was because it had never been seen before.

It's terra incognita, and it's only 60 million miles away! Amazing.
 
The Bad Astronomer said:
OK, first off, here's my blog post on the one image released so far.
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Phil, thanks for the link.

I see there are some craters with rays on Mercury. I've been a fan of such craters like Tyco on the moon, but I just now realized I didn't understand precisely how the rays might have formed. Visualizing the elliptical orbits of all the particles doesn't lead me back to an understandable source. From googling I see that the mechanism of crater rays is, generally, a mystery.

Phil, can you shed some light for us on the mechanism of crater ray formation?
 
Visually Mercury looks like the moon. Are there other features I'm missing that are a result of it being so close to the sun?
 
Let me see if I can help.

The rays are the material from inside and under the impact point of the meteorite that made the crater, that was thrown off when the crater was made.
 
Wolverine said:
How sweet is this?



It's wild to take in, especially considering we've assembled complete surface maps of so many other, more distant bodies in the solar system (even Jovian and Saturnian moons come to mind) before being in position to have a more complete view of Mercury. After all this time we can finally get more familiar with the innermost planet. More flyby imagery will be posted soon I'm sure.

Mariner 10 imagery is available here.
Click to expand...

:cool: Thanks!
 
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