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MESSENGER News Thread, news, updates and discussion
paxdan
post Apr 20 2005, 11:22 AM
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Launched on August 3rd 2004, NASA's MESSENGER will become the first spacecraft to orbit Mercury.

News and updates are availbale via Johns Hopkins University MESSENGER website and the Kennedy Space Center's MESSENGER website.

There will be an earth flyby in August followed by a couple of swings by Venus and three velocity scrubbing passages past mecury before the craft enters orbit in March 2011.

April 18, 2005 status report from JHU. Extensive JHU FAQs page here.
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Buck Galaxy
post May 29 2005, 06:19 PM
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QUOTE (paxdan @ Apr 20 2005, 11:22 AM)
Launched on August 3rd 2004, NASA's MESSENGER will become the first spacecraft to orbit Mercury.

News and updates are availbale via Johns Hopkins University MESSENGER website and the Kennedy Space Center's MESSENGER website.

There will be an earth flyby in August followed by a couple of swings by Venus and three velocity scrubbing passages past mecury before the craft enters orbit in March 2011.

April 18, 2005 status report from JHU. Extensive JHU FAQs page here.
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I for one can barely wait for Messenger. There is a big section of Mercury we've never seen, and I would love to also see close ups of the huge polar ice deposits.
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Jeff7
post May 29 2005, 08:14 PM
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QUOTE (Buck Galaxy @ May 29 2005, 02:19 PM)
QUOTE (paxdan @ Apr 20 2005, 11:22 AM)
Launched on August 3rd 2004, NASA's MESSENGER will become the first spacecraft to orbit Mercury.

News and updates are availbale via Johns Hopkins University MESSENGER website and the Kennedy Space Center's MESSENGER website.

There will be an earth flyby in August followed by a couple of swings by Venus and three velocity scrubbing passages past mecury before the craft enters orbit in March 2011.

April 18, 2005 status report from JHU. Extensive JHU FAQs page here.
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I for one can barely wait for Messenger. There is a big section of Mercury we've never seen, and I would love to also see close ups of the huge polar ice deposits.
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"Big section" is putting it mildly.wink.gif If I recall correctly, one of the Mariner spacecraft was the only probe to go past Mercury, and it photographed only a little over a fourth of the planet.

Ugh, searching for Mercury Mariner on Google turns up more matches for some damn new SUV called just that. Of course, it is a hyrbid with mileage about equal to my car, so I guess I can't really complain. smile.gif


Why is it such a long time until Messenger gets to Mercury?

Oh, seems NASA anticipated this question. Link. Orbital insertion around something so small requires a slower speed than, say, something like Cassini.

Should definitely be an interesting mission though. That's a fascinating probe too - all the adaptations needed for flying so close to the sun.
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tedstryk
post May 29 2005, 08:33 PM
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Mariner 10 Photographed 45% of Mercury, or almost half. But only basically one illumination condition was covered - due to orbital mechanics, the same side was illuminated on all three flybys. And the views of many areas were very forshortened on the limb.


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MiniTES
post May 29 2005, 09:51 PM
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MESSENGER = strained acronym. It's even worse than Hipparcos.


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JRehling
post May 31 2005, 01:27 AM
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QUOTE (Buck Galaxy @ May 29 2005, 11:19 AM)
I for one can barely wait for Messenger.  There is a big section of Mercury we've never seen, and I would love to also see close ups of the huge polar ice deposits.
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As others noted, Mariner 10 imaged about 45% of the surface, not all well. Radar has provided some nice additional coverage, not all of which is available publicly.

But we're not going to see the polar ice deposits, at least not in visible wavelengths. They are, if they exist at all, in areas of permanent shade. It wouldn't take much sunlight at 0.4 AU to melt (vaporize) ice.

I suppose it's possible that a crater floor could be imaged in light reflected off of the crater wall, if imaging conditions are just right, and if that kind of lighting isn't enough to make any such parcel of ice disappear.
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tedstryk
post May 31 2005, 02:12 AM
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QUOTE (JRehling @ May 31 2005, 01:27 AM)
As others noted, Mariner 10 imaged about 45% of the surface, not all well. Radar has provided some nice additional coverage, not all of which is available publicly.

  But we're not going to see the polar ice deposits, at least not in visible wavelengths. They are, if they exist at all, in areas of permanent shade. It wouldn't take much sunlight at 0.4 AU to melt (vaporize) ice.

  I suppose it's possible that a crater floor could be imaged in light reflected off of the crater wall, if imaging conditions are just right, and if that kind of lighting isn't enough to make any such parcel of ice disappear.
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I doubt there is reflected light weak enough to not melt ice over eons and bright enough for Messenger to use it to create an image, especially with the glare from whatever is reflecting the light.


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edstrick
post May 31 2005, 05:02 AM
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Uh... doesn't Messenger have a laser altimiter?... that measures reflectance, as well as delay-time which equals range...
I'd have to check, but I thought it did...
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Bob Shaw
post May 31 2005, 11:19 AM
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I'm reminded of the darkside images taken of the Moon by Clementine - I wonder how well Venus will illuminate the shadowed parts of Mercury (obviously, at the right time of the Mercurian year it'll be *much* brighter).


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JRehling
post May 31 2005, 03:43 PM
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QUOTE (Bob Shaw @ May 31 2005, 04:19 AM)
I'm reminded of the darkside images taken of the Moon by Clementine - I wonder how well Venus will illuminate the shadowed parts of Mercury (obviously, at the right time of the Mercurian year it'll be *much* brighter).
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A full Venus has an absolute magnitude about 4 times that of the Earth, but is 130 times farther from Mercury than Earth is from the Moon. Venusshine onto Mercury should thus be about 1/4200 of the effect of earthshine on the Moon. Depending upon the specs of a camera, that could be used for some imaging, although I suspect that the Messenger camera would not be built for light-sensitivity the way, say, New Horizon's are. The kicker: if the polar areas never see the Sun due to the geometry, they'll never see Venus either.
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JRehling
post May 31 2005, 03:52 PM
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QUOTE (edstrick @ May 30 2005, 10:02 PM)
Uh... doesn't Messenger have a laser altimiter?... that measures reflectance, as well as delay-time which equals range...
I'd have to check, but I thought it did...
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Yes, the polar ice (if it exists as such) should be detectible through several instruments, and the laser altimeter is one possibility. If they are they, we will end up with image products, I'm sure, mapping them. But we won't have traditional imagery as such (I realize the distinction can be gray -- at what extent does a collection of reflectance data equal an image??).

I'll add that we don't have proof yet that the shadows of the polar craters hold full-fledged surface ice deposits -- only that the areas are highly reflective in radar. They may be dust-covered ice that appear as normal regolith in vis/IR. Whatever is going on there may possibly not involve water ice, but sulfur, for example. Verifying the suspected ice and determining whether or not any such ice is on the surface is something to find out. Finally, the same investigation will be happening with regard to the (presumably similar) phenomenon at the lunar poles. I guess LRO will shed light on the lunar version before Messenger gets to Mercury. (It's quite a coincidence that of the two large airless worlds in the inner solar system, both have large areas of permanent shadow near their poles! -- this wouldn't be true of the Earth or Mars.)
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Bob Shaw
post May 31 2005, 04:04 PM
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Darn - I hadn't thought of that, and it's probably pretty obvious! Not only will libration effects be pretty minimal (unlike the Earth-Moon situation, where something interesting might be a goer), but as Venus and Mercury are probably in all sorts of orbital resonances there's likely to be only a few chances to view the same areas, badly illuminated at best. Oh, well, back to the drawing board.

OK, what about the Zodiacal Light...

Reflections from Comets...

Starlight...


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Chmee
post May 31 2005, 04:53 PM
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QUOTE (Bob Shaw @ May 31 2005, 12:04 PM)
OK, what about the Zodiacal Light...

Reflections from Comets...

Starlight...
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Or how about a high-yield fusion bomb detonated in orbit? Use it like a giant flash-bulb to take a picture! laugh.gif

You could even use the x-rays generated by the explosion to look for hydrogen.
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RNeuhaus
post Jun 1 2005, 02:48 AM
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Is Mercury atmosphere similar to Moon rather than Mars? What are the composition of Mercury's atmosphere (helllium, hydrogen, oxigen, potassium and sodium)? Wiill the Messengare space answer these questions?
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paxdan
post Jun 1 2005, 08:39 AM
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Earth from MESSENGER at 29.6 million km

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