MESSENGER News Thread, news, updates and discussion Options

[Paolo]

Or maybe the 3:2 resonance does so in some way?

I was thinking about this possibility too...

[nprev]

Another big difference between Mercury & Mars is that the former has a very large liquid iron/nickel core in comparison to its total size; may dramatically affect its spin behavior.

[stevesliva]

FYI, a lot of release images and discussion posted here:
http://messenger.jhuapl.edu/gallery/sciencePhotos/

[JRehling]

Dynamical effects are hard to make sense of without number crunching, but in comparing Mercury and Mars, I started here:

http://articles.adsabs.harvard.edu//full/1...000293.000.html

This says that for the nutation of Mars's axis, Jupiter has about triple the effect of Earth, but those sum to a tiny fraction (~1e-4) of the total precession.

To switch the case to Mercury, we get several times further from Jupiter, several times closer to the Sun, and more or less swap Venus in and the Earth out. So that is to say, in the case of Mercury, the planet::Sun effects should be much smaller than that of Mars, by at least a factor of 10 to 100.

Mercury's rotation is not tidally locked to the Sun, but it is clearly controlled by the Sun. Counting Venus and the Moon, three of the four closest bodies to the Sun have a lower axial inclination than any of the gas giants do (although Venus's is just less than Jupiter's) and that's not a coincidence.

[Paolo]

I have found this on the subject: On the oscillations in Mercury's obliquity
oscillations of the spin axis have a very small amplitude, and the spin/orbit resonance really has a stabilizing effect, so much so that the solution of the n-body simulation does not differ too much from a 2-body simulation

[stevesliva]

Oblique limb view:
http://messenger.jhuapl.edu/gallery/scienc...p?image_id=1097

Relatively new view at this point, but:

This image was acquired as part of MDIS's limb imaging campaign. Once per week, MDIS captures images of Mercury's limb, with an emphasis on imaging the southern hemisphere limb. These limb images provide information about Mercury's shape and complement measurements of topography made by the Mercury Laser Altimeter (MLA) of Mercury's northern hemisphere.

[Paolo]

from this NASA release The NASA Comet ISON Observing Campaign it looks like MESSENGER will still be around to observe the comet. but I still have not seen any news on the 2nd extended mission

[stevesliva]

Enhanced color Mercury map:
http://messenger.jhuapl.edu/gallery/scienc...p?image_id=1226

[scalbers]

Nice to see this map now in cylindrical format. Next on my wish list would be a similar map in "true color".

[JRehling]

According to this:
http://messenger.jhuapl.edu/gallery/scienc...mp;image_id=203
... the enhanced color images result "by displaying the negative of [a principle component image] in red, a different principal component in green, and a ratio of images taken in two WAC filters (430 nm/560 nm) in blue."

The blue seems, to the first order, to be a good way to capture true blueness. Depending on the details of those PCAs for the other two colors, this may be a pretty good rendition of "true color" (never a straightforward thing in the first place) with the saturation turned way up. So if you turn down the saturation on this enhanced color image, the result may possibly be a decent rendition of true color.

In reality, a human observer looking at Mercury would be "snowblind" so it would be essential to filter the glare in order to see any colors, and once there's a filter involved, any sense of "true" becomes quite relative. You can't just turn down the brightness without also altering color perception.

[stevesliva]

Two movies from the narrow-angle camera:
http://messenger.jhuapl.edu/gallery/scienc...p?image_id=1292
http://messenger.jhuapl.edu/gallery/scienc...p?image_id=1293

[Paolo]

I have just received confirmation that MESSENGER will survive up to 28 March 2015, when it will impact the surface of Mercury (at 58.1 N, and away from sight of Earth at impact).
Three periapsis rising maneuvers are planned in 2014, and a final one in 2015.

[Phil Stooke]

Oh boy! I smell a point on a map! (sorry, MESSENGER)

Phil

[centsworth_II]

...a point on a map!

But I guess you'll have to wait until BepiColombo gets there in 2022 to see the point.

[nprev]

Hmm. When MESSENGER impacts that will mean that all of the planets known to the ancients but Saturn (but don't forget Titan!) will have human artifacts present.

Progress of sorts.