MESSENGER News Thread, news, updates and discussion Options

[Mongo]

It could be argued that these posts are going off-topic, but it could also be argued that the study of Mercury's surface will shed light on both giant impact frequency and flood volcanism, and hence these posts are still somewhat on-topic.

The single pattern that strikes my eye is that there are only a handful of giant igneous provinces (formed by massive flood volcanism) in the past quarter-billion years, and each of them is associated with a large mass extinction, to within the dating accuracy:

Central Atlantic magmatic province (largest eruption sequence on Earth of last quarter-billion years) : end Triassic mass extinction
Siberian flood volcanism (largest eruption sequence on land of last quarter-billion years) : end Permian mass extinction
Deccan Traps (second- or third-largest eruption sequence on land of last quarter-billion years) : end Cretaceous extinction
Karoo flood volcanism (second- or third-largest eruption sequence on land of last quarter-billion years) : lower/middle Triassic extinction
North Atlantic magmatic province (about half the size of Deccan eruption sequence) : end Paleocene extinction
Ethiopian flood volcanism (about the same size as North Atlantic eruption sequence) : end Eocene extinction

By contrast, while some large impact structures appear to coincide with mass extinctions, others that are equally large appear to have had little effect:

35.6 Myr : 100 km (Popigai) + 90 km (Chesapeake Bay) --> no mass extinction
65.0 Myr : 170 km (Chicxulub) --> end Cretaceous extinction
145 Myr : 70 km (Morokweng) --> end Jurassic extinction
167 Myr : 80 km (Puchezh-Katunki) --> no mass extinction
214 Myr : 100 km (Manicouagan) --> no mass extinction

It seems to me that flood volcanism is the primary driver of most of the largest mass extinctions, with giant impacts making it worse if they happen to occur at the same time, but otherwise having little effect.

edit -- The physical extinction mechanism via flood volcanism has always seemed more plausible to me than that of giant impact. There is no doubt that giant impacts would cause huge mortality, with almost all individuals of a given species dying, but once the effects of the impact are over (within several years for all but the very largest impacts), the population would be expected to bounce back fairly quickly. On the other hand, flood volcanism would be expected to produce very hostile environmental conditions -- maybe not enough to cause massive die-offs, but enough to reduce offspring survival rates to near zero -- for centuries. I expect that while not as instantly lethal as giant impacts, flood volcanism sequences have considerably more impact on a time-scale of centuries or millennia.

[Juramike]

Interesting. Looks like maybe a one-two-three-four knockout punch was delivered to the Dinosaurs. A few big impacts, and a big volcanic event possibly caused by a few lucky hits.

I wonder if the same thing could be observed on Mercury? With several major impacts causing an igneous outpouring on Mercury's surface.

How would we figure out the precise timing and relationships?

Crater counts from orbit?

Cosmogenic nuclide counts? (lander, next mission)

-Mike

[Greg Hullender]

In the spirit of "are we there yet?" I note that Messenger just started "Orbit 7".

http://messenger.jhuapl.edu/whereis/index.php#current_orbit

Since the next Mercury flyby doesn't occur until Orbit 8, this orbit looks exactly like the last one. I think this is the first time we've had two consecutive identical orbits, but there's a lot more of that to come.

As I figure it, after flyby #2, there will be three orbits (at 116 days each) before flyby #3, and then five orbits (at 105 days each) before MOI.

--Greg

[IM4]

An interesting thing I've never heard before:

A Program to Search for Vulcanoids from MESSENGER

MESSENGER's arrival in near-Mercury space enables a search for the hypothetical population of "vulcanoids" from a vantage never before attempted. If vulcanoids exist, they are expected to orbit inside Mercury's orbit, at 0.08 to 0.21 AU. Previous vulcanoid searches (most notably from SOHO: Durda et al. 2000, Icarus 148, 312) have revealed no bodies larger than 60 km diameter. With MESSENGER, we can search for vulcanoids to at least 15 km (64x smaller in mass), but limited to the outer 50% of the vulcanoid cloud's volume. Using the Wide Angle Camera (WAC) of MESSENGER's Mercury Dual Imaging System (MDIS), we cover a 10.5x10.5-deg field in a single 1024x1024 CCD image. We use the "clear" filter with the maximum WAC exposure of 10 seconds. We observe both east and west of the Sun, with a 1x2 mosaic on each side, covering 10 deg of longitude and 19 deg of latitude (roughly 8x15 Mkm at the distance of the Sun). Our observation cadence allows us to definitively reject cosmic rays and to distinguish (from motion) the class of object (e.g., vulcanoid vs. near- or inner-Earth asteroid). Spacecraft pointing restrictions limit solar elongation to > 30 deg. Therefore, we will always observe near spacecraft perihelia ( 0.3 AU) to search as close to the Sun as possible. There are 12 such opportunities prior to Mercury orbit insertion in March 2011, but we cannot observe during certain mission-critical activities. Our first data (240 images spanning 9 days) were acquired in June 2008; this sequence was designed to refine our observing techniques, assess limiting magnitudes, verify detectability of known objects, and make an initial search. We have verified that we reach at least our nominal goal of Vmag=8. Data analysis is ongoing; we will describe the program and give an assessment of the data.

Looks like a kind of top secret program, no news on mission website, no papers. The only thing I found in the web is presentation available only through Google cache.

[sci44]

An interesting thing I've never heard before:

A Program to Search for Vulcanoids from MESSENGER

At long last, we may be able to explain Mercury's erratic orbit..
Top secret? I think this has been mooted for a while..

[scalbers]

Messenger presentation will be shown live from the AGU conference (Monday Dec 15 0800-1000 PST):

http://www.agu.org/meetings/fm08/

[peter59]

Several new images released, probably in connection with AGU conference.
http://messenger.jhuapl.edu/gallery/scienc...hp?gallery_id=2

[Juramike]

Ha! Vindicated!

One of the images recently released is a high-res version of the Southern basin we discussed in the Mercury Flyby 2 thread:

Recent MESSENGER release: http://messenger.jhuapl.edu/gallery/scienc...mp;image_id=279
Image discussed on UMSF: Mercury Flyby 2 thread, post #69

[scalbers]

Yes, discussed first right here at UMSF. I think this basin was called Manet in the talks.

Also some nice color imagery of Raditladi with an enhanced blue ring of mountains. Clark Chapman had a good discussion about its age (possibly about 1 billion years).

The newly released NAC mosaic might be nice to use in my map if I can figure out how to best splice it in. I'm so used to the spacecraft perspective images that I have to think twice about how to add in an already remapped image.

[Phil Stooke]

There have been regular image releases from MESSENGER - here's the latest in case people have forgotten about the innermost planet.

Phil

http://messenger.jhuapl.edu/gallery/scienc...mp;image_id=292

[mps]

Btw, MESSENGER was recently hunting for Vulcanoids

[tasp]

Regarding targets of opportunity such as possible Vulcanoids, Mariner 10 attempted some images of comet Kohoutek (sp), but I don't recall how far from the sun the comet was at the time of the observation.

[Guest_Sunspot_*]

Btw, MESSENGER was recently hunting for Vulcanoids

I think they tried searching for Vulcanoids in SOHO LASCO images some time ago...presumably nothing was found.

[Paolo]

I think they tried searching for Vulcanoids in SOHO LASCO images some time ago...presumably nothing was found.

This interesting article seems to prove that Vucanoids are unlikely to exist to this day

[MarkG]

Messenger JHUAPL site seems to be down.... ?