The spacecraft is feeding back all kinds of great data and the instruments are working nicely.
I didn’t see Cruel Wife very much that year of working at the UofM so it is a very pleasant payoff to see the instrument working so darned well… You. Have. No. Idea. … how tickled I am that the UofM’s instrument is performing so fantastically well. It was a tense and cranky year when I was there but this made it worthwhile…
This, from JHU-APL… read the lava part, which is cool, but the really cool part is the exosphere part.
Orbital Observations of Mercury Reveal Flood Lavas, Hollows, and Unprecedented Surface Details
After only six months in orbit around Mercury, NASA’s MESSENGER spacecraft is sending back information that has revolutionized the way scientists think about the innermost planet. Analyses of new data from the spacecraft show, among other things, new evidence that flood volcanism has been widespread on Mercury, the first close-up views of Mercury’s “hollows,” the first direct measurements of the chemical composition of Mercury’s surface, and the first global inventory of plasma ions within Mercury’s space environment.
The results are reported in a set of seven papers published in a special section of Science magazine on September 30, 2011.
“MESSENGER’s instruments are capturing data that can be obtained only from orbit,” says MESSENGER Principal Investigator Sean Solomon, of the Carnegie Institution of Washington. “We have imaged many areas of the surface at unprecedented resolution, we have viewed the polar regions clearly for the first time, we have built up global coverage with our images and other data sets, we are mapping the elemental composition of Mercury’s surface, we are conducting a continuous inventory of the planet’s neutral and ionized exosphere, and we are sorting out the geometry of Mercury’s magnetic field and magnetosphere. And we’ve only just begun. Mercury has many more surprises in store for us as our mission progresses.”
MESSENGER Reveals Flood Volcanism
For decades scientists had puzzled over whether Mercury had volcanic deposits on its surface. MESSENGER’s three flybys answered that question in the affirmative, but the global distribution of volcanic materials was not well constrained. New data from orbit show a huge expanse of volcanic plains surrounding the north polar region of Mercury. These continuous smooth plains cover more than 6% of the total surface of Mercury.
The volcanic deposits are thick. “Analysis of the size of buried ‘ghost’ craters in these deposits shows that the lavas are locally as thick as 2 kilometers” (or 1.2 miles), explains James Head of Brown University, the lead author of one of the Science reports. “If you imagine standing at the base of the Washington Monument, the top of the lavas would be something like 12 Washington Monuments above you.”
According to Head, the deposits appear typical of flood lavas, huge volumes of solidified molten rock similar to those found in the few-million-year-old Columbia River Basalt Group, which at one point covered 150,000 square kilometers (60,000 square miles) in the northwest United States. “Those on Mercury appear to have poured out from long, linear vents and covered the surrounding areas, flooding them to great depths and burying their source vents,” Head says.
Scientists have also discovered vents, measuring up to 25 kilometers (16 miles) in length, that appear to be the source of some of the tremendous volumes of very hot lava that have rushed out over the surface of Mercury and eroded the substrate, carving valleys and creating teardrop-shaped ridges in the underlying terrain. “These amazing landforms and deposits may be related to the types of unusual compositions, similar to terrestrial rocks called komatiites, being seen by other instruments and reported in this same issue of Science,” Head says. “What’s more, such lavas may have been typical of an early period in Earth’s history, one for which only spotty evidence remains today.”
As MESSENGER continues to orbit Mercury, the imaging team is building up a global catalog of these volcanic deposits and is working with other instrument teams to construct a comprehensive view of the history of volcanism on Mercury.
Mercury’s Surface and Exospheric Composition, Up Close and Personal
[Other things were said here]
MESSENGER has also collected the first global observations of plasma ions in Mercury’s magnetosphere. Over 65 days covering more than 120 orbits, MESSENGER’s Fast Imaging Plasma Spectrometer (FIPS) made the first long-term measurements of Mercury’s ionized exosphere.
The team found that sodium is the most important ion contributed by the planet. “We had previously observed neutral sodium from ground observations, but up close we’ve discovered that charged sodium particles are concentrated near Mercury’s polar regions where they are likely liberated by solar wind ion sputtering, effectively knocking sodium atoms off Mercury’s surface” notes the University of Michigan’s Thomas Zurbuchen, author of one of the Science reports. “We were able to observe the formation process of these ions, one that is comparable to the manner by which auroras are generated in the Earth atmosphere near polar regions.”
The FIPS sensor detected helium ions throughout the entire volume of Mercury’s magnetosphere. “Helium must be generated through surface interactions with the solar wind,” says Zurbuchen. “We surmise that the helium was delivered from the Sun by the solar wind, implanted on the surface of Mercury, and then fanned out in all directions.
“Our results tell us is that Mercury’s weak magnetosphere provides the planet very little protection from the solar wind,” he continued. “Extreme space weather must be a continuing activity at the surface of the planet closest to the Sun.”
“These revelations emphasize that Mercury is a fascinating world that is unmatched in the solar system,” says Blewett. “We have barely begun to understand what Mercury is really like and are eager to discover what Mercury can tell us about the processes that led to formation of the planets as we see them today.”
Universe Today has some neat stuff on MESSENGER/Mercury as well. (h/t to Black Lab on Meth)
And then one of my bosses sent me this article, too… Mercury is hot as hell and appears to match it pretty closely in the description, but it’s not quite as bad as Hell because Mercury doesn’t play Barry Manilow music.