Science results from MESSENGER's first flyby, Science publication July 4 Options

[belleraphon1]

All...

there will be a MESSENGER Update teleconference today (July 3rd, 2008) at 2:00pm EDT

Below is the link for live audio streaming...

http://www.nasa.gov/news/media/newsaudio/index.html


http://messenger.jhuapl.edu/news_room/details.php?id=99
NASA to Reveal New Discoveries from Mercury
NASA will host a media teleconference Thursday, July 3, at 2 p.m. EDT, to discuss analysis of data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft's flyby of Mercury earlier this year.

The spacecraft is the first designed to orbit the planet closest to the Sun. It flew past Mercury on Jan. 14, 2008, and made the first up-close measurements since Mariner 10's final flyby in 1975.

Analyses of the data show volcanoes were involved in the formation of plains. The data also suggest the planet's magnetic field is actively produced in its core. In addition, the mission has provided the first look at the chemical composition of Mercury's surface. The results will be reported in a series of 11 papers published July 4 in a special section of Science magazine.

The teleconference participants are:
- Marilyn Lindstrom, program scientist, NASA Headquarters
- Sean Solomon, principal investigator, Carnegie Institution of Washington
- James W. Head III, professor of geological sciences, Brown University, Providence, R.I.
- William McClintock, senior research associate, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder
- Thomas H. Zurbuchen, associate professor, Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor

Reporters may access the embargoed science press package materials by registering with EurekAlert! at www.eurekalert.org and e-mailing scipak@aaas.org to expedite their registration. Once registered, they may log in directly at: http://www.eurekalert.org/jrnls/sci/.

To participate in the teleconference, reporters in the United States should call 1-888-455-3616 and use the passcode "messenger." International reporters should call 1-517-623-4705. Audio of the teleconference will be streamed live at:
http://www.nasa.gov/newsaudio.

When the briefing begins, related images will be available at:
http://messenger.jhuapl.edu/news_room/telecon4.html.

Craig

[elakdawalla]

The MESSENGER topic had got huge so I thought it was time for a new thread.

Here's the links for the press graphics:
http://messenger.jhuapl.edu/news_room/telecon4.html

--Emily

[elakdawalla]

Main talks are over. Most of it is pretty similar to the last press briefing; I'd say the most surprising and interesting results are from FIPS, who think they found water(!?!) in the exosphere...

--Emily

[belleraphon1]

Thanks Emily....

I was not sure which thread to put the press briefing announcement.

Unable to listen in myself....

From the MESSENGER Mission News..
http://messenger.jhuapl.edu/news_room/details.php?id=100

"The magnetosphere is full of many ionic species, both atomic and molecular and in a variety of charge states. What is in some sense a ‘Mercury plasma nebula’ is far richer in complexity and makeup than the Io plasma torus in the Jupiter system. The abundances of silicon, sodium, and sulfur relative to oxygen in the solar wind are too low, and their charge states — ionization — are too high to account for the abundances we measured, so there is no doubt that this material came from the planet’s surface. This observation means that this flyby got the first-ever look at surface composition.”

Plus the spectra showing water group ions... neat! See slide 5.4 of the presentation materials
http://messenger.jhuapl.edu/news_room/multi04.html

Though I draw a complete blank on exospheres and magnetospheres.... there is just something thrilling about reading passages like the one above. Every world is full of complexities, often invisible to tha eye...

Craig

[nprev]

Hmm...decompositional products of H2O. Not far-fetched.

My guess is that the polar cometary deposit(s) are at least getting sputtered by the magnetosphere; they might even be slowly sublimating from thermal conduction via the crust. Strongly doubt that it's native Mercurian water; that had to be gone aeons ago.

[Juramike]

Hmm...decompositional products of H2O. Not far-fetched.

...and we know the MS signals are not due to methane (CH4, 15 amu) or ammonia (NH3, 17 amu) because....?

[Phil Stooke]

... because they're at 16 and 18, not 15 and 17?

Phil

[nprev]

Good point, Mike. I don't think we do know with utter certainty, but the water-group ion interpretation is what they're going with as the most likely. I notice there's a nice little carbon spike, too.

[TheChemist]

I only have access to the abstract :

"MESSENGER Observations of the Composition of Mercury's Ionized Exosphere and Plasma Environment
Thomas H. Zurbuchen,* Jim M. Raines, George Gloeckler, Stamatios M. Krimigis, James A. Slavin, Patrick L. Koehn, Rosemary M. Killen, Ann L. Sprague, Ralph L. McNutt, Jr., Sean C. Solomon

The region around Mercury is filled with ions that originate from interactions of the solar wind with Mercury's space environment and through ionization of its exosphere. The MESSENGER spacecraft's observations of Mercury's ionized exosphere during its first flyby yielded Na+, O+, and K+ abundances, consistent with expectations from observations of neutral species. There are increases in ions at a mass per charge (m/q) = 32 to 35, which we interpret to be S+ and H2S+, with (S+ + H2S+)/(Na+ + Mg+) = 0.67 ± 0.06, and from water-group ions around m/q = 18, at an abundance of 0.20 ± 0.03 relative to Na+ plus Mg+. The fluxes of Na+, O+, and heavier ions are largest near the planet, but these Mercury-derived ions fill the magnetosphere. Doubly ionized ions originating from Mercury imply that electrons with energies less than 1 kiloelectron volt are substantially energized in Mercury's magnetosphere."

http://www.sciencemag.org/cgi/content/abstract/321/5885/90


* Edit * : A nice summary and some answers from Dr. Zurburchen at the PS blog.

http://www.planetary.org/news/2008/0703_ME...onished_to.html

[ngunn]

I've just been doing some back-of-envelope calculations with the new value of Mercury's magnetic dipole moment. It is given in terms of the cube of Mercury's radius (!) Converting to amp.metre squared (or equivalently tesla.metre cubed) I get 3.8 x 10 to the power 12. This compares with 14 x 10 to the power 12 for Ganymede - remarkably similar really, considering the mechanisms are likely very different. However I would welcome independent confirmation of my hasty arithmetic.

EDIT: link to abstract-
http://www.sciencemag.org/cgi/content/abst...sci;321/5885/82

[nprev]

Silly question re the spectrum: How come it doesn't register any hydrogen, monatomic or diatomic? Is this an instrument limitation, or is it just indistinguishable from the solar wind background?

[3488]

I thought this was very interesting.

First identified shield volcano on Mercury?

Image of 95 KM wide possible shield volcano with a 25 km wide caldera, in south west Caloris Basin floor.


Map of area shown above.


My attempt at cropping & enlargening the 25 KM wide caldera.


Andrew Brown.

[nprev]

Nice work, Andrew!

Sure looks like a volcano to me. I'd been expecting Messenger to find a few, although possibly not until it achieved orbit.

I'm more then a bit intrigued by the difference in color between the volcano's shield and the surrounding terrain. Will be interesting to see the age estimates of such features. Does anyone know if the rate of micrometeoritic surface erosion at Mercury is expected to be greater than that of, say, the Moon due to the fact that it's so much deeper in the Sun's gravity well?

[3488]

Hi nprev,

I have given that some thought. Logic would suggest that micrometeoroid impacts to be more numerous & energetic on Mercury than on the Moon, due to the sun's greater pull @ approx 0.35 AU.

I also wonder, if it's actually very much less though, as radiation pressure & the solar wind will be greater, some 10 -11 times greater than on the Moon?

To me that feature is a volcano. The lighter material maybe ash?

I don't know if there are any higher resolution images as yet of this volcano? Would be interesting to look for lava flows, lava tubes, etc.

Andrew Brown.

[nprev]

Yeah...forgot about solar wind erosion, although the magnetic field presumably offers some protection from that.

Damned interesting, though. We're seeing some extremely complex features--some of those craters with mixed dark/light terrain are just mind blowing--and frankly I can only stare and say "Wow!" without attempting an explanation at this point. IIRC, one of the Messenger scientists said that Mercury is looking more like Mars then the Moon; I can believe that analogy. Certainly the crust seems to be chemically differentiated to a much higher degree then that of the Moon.