Holy guacamole. A-ma-zing.

Labels: asia, satellite imagery, water resources

Wow. You've got to check out these amazing new images from Saturn.

Yet another tip o' the hat to Diego H. for passing this link on to me...

Labels: astronomy, planetary geology, satellite imagery

NASA's Earth Observatory runs an invaluable public service with its "Image of the Day" series. Now they've got a decade's worth of images, and they want to know which of 50 finalists you think is the best. Go and vote (so hard to choose!), and on April 29, they will reveal the winner.

My personal choice? I'll bet you think it looks familiar... It's this one:

Labels: contest, satellite imagery, websites

The April meeting of the Potomac Geophysical Society will be held April 16th at the Fort Myer Officers' Club in Arlington, VA in the Campaign Room. This month's talk will be: Mapping Rocks and Minerals using Advanced Spaceborne Thermal Emission and Reflection Radiometer data, by John 'Lyle' Mars (USGS, Reston, VA).

Abstract:
The Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) measures reflected radiation in 3 bands in the 0.52 to 0.86 micrometer wavelength region (VNIR); 6 bands in the 1.6 to 2.43 micrometer wavelength region (SWIR); and 5 bands of emitted radiation in the 8.125 to 11.65 micrometer wavelength region (TIR) with 15-m, 30-m, and 90-m resolution, respectively. ASTER also has a backward-looking VNIR telescope with 15-m resolution. The swath-width is 60 km, but off-nadir pointing capability extends the total cross-track viewing of ASTER to 232 km. ASTER VNIR bands are positioned to delineate Fe absorption features, ASTER SWIR bands can delineate Al-OH, Fe Mg-OH, H-O-H and CO3 absorption features, and TIR bands are particularly useful for mapping Si-O vibrational features. This talk will demonstrate techniques and results of minerals and lithologic mapping using ASTER data. Mineral and lithologic maps compiled from ASTER data include parts of the western U.S., Afghanistan, Iran, Kazakhstan, Morocco, and Pakistan. Mapping algorithms include band ratio, matched filtering, and logical operators. Minerals and mineral groups mapped using ASTER data include, muscovite, argillic and phyllic-altered rocks, carbonate rocks, hydrothermal quartz, and quartz-rich rocks.

Biographical Information:
Lyle Mars is currently a Research Geologist in Remote Sensing at the USGS. He got his PhD from the University of Kentucky in 1995. His research is focused on gaining a better understanding of the spectral characteristics of a wide range of earth materials and how these characteristics are remotely sensed. This work is enhancing our abilities to identify important mineral resources, elucidate global tectonic relationships and facilitate recognition of environmental degradation related to mining. He investigates the spectral properties of rocks, minerals and vegetation and applies spectroscopic observations to research in multispectral and hyperspectral remote sensing studies. Most of his remote sensing projects are focused on spectral data in the 0.35 to 14.0 micrometer region. This research is applied to new remote sensing techniques in the identification of minerals, rock types, stratigraphy, structures, and vegetation. His spectroscopic research is also used in the calibration of new remote sensing systems such as the Advanced Spaceborne Thermal Reflection and Emission Radiometer (ASTER), Hyperion, and Hymap. Prior to USGS he was a Visiting Assistant Professor at George Mason University.

Reception at 6:30. Dinner at 7:30. Talk at 8:30 PM. Allow 15 minutes for security entering Ft. Myer as all civilian vehicles are searched. To ensure access to and from Fort Myer use the Hatfield Gate, open 24 hours a day. If you wish to attend dinner ($25), please make reservations with Joydeep Bhattacharyya at 703-676-4373 or via E-mail at Joydeep.bhattacharyya@saic.com. If you wish, please feel free to attend the talk without dinner. Non-members and guests are welcome. Visit the PGS web site for new meeting announcements, etc. Please send changes of address or email to Joydeep.bhattacharyya@saic.com.

Labels: minerals, pgs, satellite imagery

Last week, I mentioned the impending launch of the Orbiting Carbon Observatory... Well, last night at the launch, things didn't work out so well...

NASA Satellite Fails to Reach Orbit (New York Times)
NASA satellite crashes (Los Angeles Times)
Seven years' work on satellite crashes and burns in 12 minutes (Scotsman)
NASA satellite launch fails (Newsday)
and from NASA themselves, the grim Launch Mishap Ends OCO Mission

What a bummer. All that potential knowledge, snuffed out before we even got a chance to see it.

Labels: climate change, CO2, global warming, news, satellite imagery

NASA is launching a new satellite next week to monitor the atmosphere's carbon flux from a outside-the-planet perspective. It's called the Orbiting Carbon Observatory (OCO). Hopefully this will complement and give context to our current ~100 monitoring stations around the world (point measurements) for a truly global picture of our atmosphere's carbon inputs and outputs.

According to the NASA OCO website, the satellite will map the globe "once every 16 days for at least two years. It will do so with the accuracy, resolution and coverage needed to provide the first complete picture of the regional-scale geographic distribution and seasonal variations of both human and natural sources of carbon dioxide emissions and their sinks-the reservoirs that pull carbon dioxide out of the atmosphere and store it."

I can't wait to learn what we don't currently know about the carbon system. This is a tool that's long overdue!

Labels: climate change, CO2, satellite imagery

EARTH magazine commissioned me to make a new t-shirt design for their "Where on Earth?" contest giveaway. Here's what I came up with...

(I've clipped the left and right edges with this jpg, to make it fit into blog-space.)

Labels: art, satellite imagery

Those aren't insects swarming all over the ground: those are people!

From the GeoEye satellite, via Google Earth, via the Google Earth blog.

Labels: dc, politics, satellite imagery

The perpetually-interesting site Oddee hosted a series of satellite images of the Earth today, including this one from April of last year. Somehow I missed it then...

The image, originally from NASA's Earth Observatory (one of the finest websites I know of for those interested in Earth science), shows a collection of volcanoes in the western Arabian Peninsula. A large version of the image (unlabeled) is here.

The most spectacular thing about this image is the color contrast between the volcanoes on the left versus the volcanoes on the right. This spectacular contrast is indicative of the rock types involved in each volcano. On the left, felsic lava was erupting, which cooled into the extrusive rock rhyolite. On the right, mafic lava was erupting, which cooled into the extrusive rock basalt. Mafic igneous rocks like basalt have a higher proportion of the elements iron, magnesium, and calcium as compared to elements like silicon, potassium, and sodium. Felsic igneous rocks are, in a sense, distillates of mafic source rocks: they are made of minerals that are more easily melted.

Also worth noting is the way the basalt overlaps the rhyolite between Jabal Bayda' and Jabal Abyad tells us that the rhyolite came first, and the basalt came second, an example of relative dating. And these insights can be gleaned from space... or more accurately, from our computer screens, depicting an image from space. That's pretty incredible, when you think about it.

FYI, here's what NASA's William Stefanov wrote as the caption for this exceptional image:

The western half of the Arabian Peninsula contains not only large expanses of sand and gravel, but extensive lava fields known as haraat (harrat for a named field). One such field is the 14,000-square-kilometer Harrat Khaybar, located approximately 137 kilometers to the northeast of the city of Al Madinah (Medina). The volcanic field was formed by eruptions along a 100-kilometer, north-south vent system over the past 5 million years. The most recent recorded eruption took place between 600-700 AD.

Harrat Khaybar contains a wide range of volcanic rock types and spectacular landforms, several of which are represented in this astronaut photograph. Jabal ("mountain" in Arabic) al Qidr is built from several generations of dark, fluid basalt lava flows. Jabal Abyad, in the center of the image, was formed from a more viscous, silica-rich lava classified as a rhyolite. While the 322-meter high Jabal al Qidr exhibits the textbook cone shape of a stratovolcano, Jabal Abyad is a lava dome; a rounded mass of thicker, more solidified lava flows. To the west (image top center) is the impressive Jabal Bayda'. This symmetric structure is a tuff cone, formed by eruption of lava in the presence of water. The combination produces wet, sticky pyroclastic deposits that can build a steep cone structure, particularly if the deposits consolidate quickly.

White deposits visible in the crater of Jabal Bayda' and two other locations to the south are sand and silt that accumulate in shallow, protected depressions. The tuff cones in the Harrat Khaybar suggest that the local climate was much wetter during some periods of volcanic activity. Today, however, the regional climate is hyperarid - little to no yearly precipitation - leading to an almost total lack of vegetation.

Labels: basalt, blogs, igneous, middle east, satellite imagery, volcano, websites

This image came to my attention the other day via Lutz's Geoberg blog. It's one of the high-res images provided by the newly-launched satellite, the GeoEye-1, which is supplying new images to Google*. The image shows a marginal lake associated with an alpine glacier in Kenai Fjords National Park, Alaska (just south of Seward):


The top of the above image is not north; it's southwest. Mentally rotate it, and you can see that the resolution is a lot better than the current level on Google Earth and Google Maps:


The thing that struck me about the new GeoEye image, aside from its beauty, is the distinct pattern of iceberg sizes in the lake: freshly calved off the glacier, the biggest icebergs are close to their source, while further away the icebergs are smaller. This pattern struck me as being analogous to sediment. Fresh from its source, sedimentary particles are at their largest size, and the further away they travel, the more weathering they experience. This weathering (in particular of the physical variety) tends to break them down into smaller pieces. Adjacent to an orogenic belt, for instance, you tend to find deposition of sedimentary particles shed off the uplifting mountains. As a general rule, these are of the largest sizes and the greatest volume closest to the source, and then particle size and stratum thickness both diminish with increasing distance from the orogen.

For a North American example, consider the Catskill Clastic Wedge, a tick pile of sediments shed off the late Devonian Acadian Orogeny along the east coast. Here's a cross-sectional view** (pre-Alleghany Orogeny deformation) of the wedge, running from the Bay of Fundy west to Michigan:


Same pattern! Coarse stuff, and more volume of stuff, close to the source. Finer stuff, and less volume of stuff, further from the source. Just like the iceberg, except the weathering of the icebergs is mainly thermal, while the weathering of the sediments is physical, accompanied by depositional sorting by the transporting currents of water.

__________________________________

* An original version of this post misidentified Google as the owners of the GeoEye-1, as opposed to the company called GeoEye, which sells images to Google. Thanks to Bruce Haley for the correction. (updated 8:14AM eastern time on Dec. 9, 2008)
** Image redrawn (by me) from an original in Prothero & Dott (2003).

Labels: alaska, analogies, art, canada, glacial landforms, glaciation, maine, michigan, mountains, new york, satellite imagery, sediment

Saw this amazing image of an alluvial fan in Iran yesterday on NASA's Earth Observatory's "Image of the Day":



All those elongated rectangles called to mind the famous oil painting The Kiss by Gustav Klimt:



Clearly, another case of nature imitating art!

Labels: art, satellite imagery, sediment

Mars has a new robot geologist on its surface, as of last night at just before 8pm (E.S.T.). The Mars Phoenix lander arrived in Mars' north polar region after an apparently dicey landing sequence that went off without a hitch. It unfurled its solar panels and started taking pictures, like the one at the left. That's a new view of the planet thought most likely to give us insights into the possibility of life elsewhere in the universe.

Why the pole? That's where the water is. Remote sensing indicates ice just a few inches below the surface in this area, and the geomorphology seems to back that up. Visible even in this earliest photo, polygonal shaped features suggest repeated freeze-thaw action. (Similar freze-thaw action in Earth's polar regions produces similar features, like these:



That's the way geology works, right? The principle of uniformity suggests that uniform physical laws operating over vast ranges of time and space will produce similar phenomena in different locations. It remains to be seen how valid this principle is in guiding our exploration of other planets, but with Mars it appears that there are some real similarities. And why do we care where the water is? Because on Earth, all life needs water. Figuring out whether life exists elsewhere in the universe has huge implications for our place in the cosmos.

Labels: mars, planetary geology, satellite imagery, tech

What's the difference between these pictures?

... Find out at the NASA Earth Observatory feature page that examines "Cities at night: the view from space."

Labels: environmental, maps, satellite imagery

Check out the aerial landscape photography of Michael Collier, as showcased on this website.

Collier's photographs are currently on exhibit at NSF in Arlington, VA.

Labels: art, satellite imagery

Labels: satellite imagery

This is what the eastern U.S. looked like as of yesterday. No snow in the DC area, but it sure is cold out there. Reminds me of my favorite Robert Mankoff cartoon (below).The satellite image is courtesy of NASA's Earth Observatory.

Labels: cold, global warming, humor, satellite imagery

New research indicates that one possible source for the decline in Atlantic sea-surface temperature in 2006 may have been dust from the Sahara Desert. The image at left shows a dust plume being blown westward off the coast of Mauritania.

William Lau and Kyu-Myong Kim of NASA's Goddard Space Flight Center have concluded that airborne Saharan dust over the Atlantic was likely responsible for low temperatures because it effectively blocked sunlight from reaching the ocean's surface. Their research was published in EOS and the International Journal of Climatology.

In 2005, when the Atlantic was warmer, there were 15 hurricanes (including Katrina and Rita). In 2006, many people were expecting similar numbers and strengths of storms. However, there were only five that year due to lower sea-surface temperatures. Lau and Kim estimate that the dust was responsible for 30%-40% of the cooling effect.

Read more about it here and here.

Meanwhile, another team of researchers has found that these well-traveled dust particles may be a potential vector of disease. In the current issue of Environmental Microbiology, Anna Gorbushina and William Broughton (of the University of Geneva) report that germs can "hitchhike" on dust particles, allowing them to spread from continent to continent. The researchers used geochemical analyses to determine that samples of dust originally collected by Charles Darwin in Barbados actually originated in Africa. Furthermore, bacteria and tiny fungi were found stuck to the dust grains. The species found were not pathogenic (disease-causing), and the researchers note that most pathogens are not hardy enough to survive a long voyage on the Dust Express.

Read more about it here.

Labels: disease, dust, global warming, hurricanes, satellite imagery, silt

A well-illustrated article by NASA's Earth Observatory discusses the issue of coal mining in Appalachia. Estimates are that we have 100 years or more coal reserves in the world -- far more than oil. The problem is, coal is dirty. Appalachian coal in particular is high in pyrite (FeS2), so that when it is burned, sulfuric acid is generated.

And then, of course, there is the issue of greenhouse emissions. When we heat or get electrical power from the burning of coal, we are reversing an ancient photosynthetic reaction. In the Carboniferous, great swampy deltas (much like the modern Mississippi Delta) stretched across what is today West Virginia. Great rivers draining the young Appalachians flowed west into a shallow epeiric sea. In these muddy deltas, plants grew in profusion. Those plants did what modern plants do: they sat in the sunlight and used its energy to fuse CO2 and H2O into sugars -- plant food. Before they got a chance to use that constructed food, and before any animals had a chance to eat the plants, they were smothered beneath additional layers of sediment, and the efforts of their photosynthesis were locked away underground. This went on for millions and millions of years. Now, humanity has discovered that coal burns well, releasing energy originally generated by the Sun 300 million years ago. Using coal for energy reverses the ancient photosynthetic reaction. When we burn coal, we are combining the coal's "carbohydrates" with oxygen, and re-producing the initial ingredients (CO2 and H2O) in the process. Of course, when water vapor in the air reaches a high concentration, it condenses and precipitates. Carbon dioxide is also removed from the atmosphere by geologic processes, but at a much slower rate. Hence the rise in atmospheric CO2 levels since the Industrial Revolution (when coal-burning picked up pace).

The Earth Observatory article deals with another issue, though: the question of how best to get at coal, given that it's underground in strata with other rock layers atop them. Every month, it seems like there is an item in the news about how there's been an accident in some underground coal mine somewhere in the world, always with a dozen or more miners killed or trapped. In West Virginia, strip mining is a favored tactic. It's safer to coal miners because it occurs at the surface, but there's the rub: The surface is also where everything else happens, too. When miners strip away the overlying rock layers, they also strip away the forest and everything that lives there. Often, unwanted rock is dumped into neighboring valleys, which causes a lot of stress on the freshwater ecosystems present in streams draining that valley.

Check out the article here. It is illustrated with great maps and satellite photos.

Labels: CO2, coal, global warming, mining, satellite imagery