The UCLA Institute for Planets and Exoplanets, The UK Center for Astrobiology and the NASA Astrobiology Institute held a meeting on campus last week where planetary scientists from around the world discussed their research determining the present-day habitability of Mars. While the conference has concluded, the talks were recorded and can be streamed publicly online here.
Read more about the conference from these media outlets:
Top scientists debate whether life could survive on Mars
The latest issue of Science magazine features the discovery of ice on Mercury, preserved within permanently shadowed areas inside north polar craters. The cover of the magazine showcases a beautiful high-resolution map that combines topographic and thermal model measurements to identify the places at Mercury’s north pole where water ice remains stable.
Creating a cover for the prestigious journal Science is no easy feat. In this case, Professor David Paige harnessed the power of hundreds of computers working for dozens of hours to create the final version. Read more about Paige’s cover here.
On December 7, 2012, undergraduate students in Professor Axel Schmitt’s mineralogy course (ESS 51) presented their research projects to the Earth and Space Sciences department at UCLA.
Jason Brouwer, an ESS 51 student, completed his end of term project studying Native American arrowheads that he collected in the Santa Barbara and Ventura counties. Brouwer used X-ray Fluorescence Spectroscopy to determine the amounts of certain trace elements within the obsidian arrowheads left behind by Chumash tribes. He found his measurements almost precisely matched obsidian deposits 200 miles away in southeastern California. He concluded that the local Chumash likely traded for the obsidian arrowhead with the Coso people indigenous to that specific area of the Mojave Desert. Possessing an avid interest in Native American cultures and artifacts prior to taking the course, Brouwer was excited to find a way to turn his passion into a class project.
The ESS51 course, entitled “Mineralogy: Earth and Planetary Materials” focuses on mineral structure, crystal chemistry, and laboratory study. Students in the class learn hand sample identification, optical and electron microscopy, and spectroscopic techniques.
A thermal map of the north polar region of Mercury. The blue areas denote permanently shadowed regions cold enough for water ice to be stable on or below the surface.
Planetary scientists have identified water ice and anomalously dark deposits within permanently shadowed regions at Mercury’s north pole. Using data collected by NASA’s MESSENGER spacecraft, a UCLA team crafted the first accurate thermal model of the solar system’s innermost planet that successfully pinpoints extremely cold regions where ice has been found on or below the surface. They conclude that the newly discovered black deposits are a thin dark crust of residual organic material brought to the planet over the past several million years by water-rich asteroid and comet impacts.
Understanding how water ice has been preserved on Mercury and where it came from may help scientists determine the conditions necessary for sustaining life on other planets.
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This research, one of three MESSENGER papers published online today and in an upcoming print edition of Science, sheds light on the longstanding issue of ice on Mercury. The sun-scorched planet is now revealed to have extensive water ice deposits at its poles by several independent lines of evidence.
In the early 1990s, scientists were surprised to find that areas near Mercury’s poles were unusually bright when observed with radar from Earth, a potential indication that ice might be present.
Lead author David Paige, a self-described “professional ice finder,” has studied the poles of planetary bodies in the solar system from Mercury to Pluto.
“Mercury is the innermost planet in the solar system and arguably it’s among the least explored,” said Paige, a professor of Earth and space sciences at UCLA. “The surface of Mercury exhibits the most extreme range of temperatures of any body we know of in the solar system.”
Within a single polar crater on Mercury there are places that reach the oven-like temperature of 500 degrees Fahrenheit within sight of areas cold enough to freeze and preserve water ice for billions of years. These “natural freezers” exist within shadowed areas inside polar crater rims that never experience direct sunlight due to the low angle of the Sun at such high latitudes, Paige said.
Paige was able to use the first detailed topographic map of Mercury’s north polar region produced by MESSENGER to generate an accurate thermal model of the pole. His calculations of Mercury’s subsurface temperatures are a near perfect match to Earth-based radar observations and surface brightness measurements made by the Mercury Laser Altimeter (MLA) instrument onboard the orbiting spacecraft.
Where his temperature model predicts water ice should be stable on the surface, the MLA nearly always measures unusually bright patches, indicative of surface ice deposits. In places where it is too warm for surface ice but cold enough for ice to exist beneath the surface, the MLA sees unusually dark material.
“This stuff we find covering the ice is darker than the rest of Mercury, which is already a really dark planet. That’s amazing,” said Paige. “At the very least it means there is something out of the ordinary going on inside these permanently shadowed areas where the ice has accumulated.”
The mysterious dark substance likely arrived on Mercury as part of comets and asteroids that periodically crash into the planet, bringing water ice and a diverse cocktail of organic material, Paige said. In the searing daytime heat of Mercury, the only place water and organics can survive is within permanently shadowed craters.
But only in the very coldest areas of the permanently shadowed regions can water ice exist on the surface. In the warmer shadowed areas, the top layers of ice begin to evaporate away into space, leaving behind a layer of hardy organic molecules that are stable at higher temperatures and turn black over time when exposed at the surface. Once the dark layer is thick enough, it protects the ice underneath, allowing a subsurface ice deposit to survive.
“There are areas on the surface where it is too hot for ice to exist, but radar data from Earth show something bright reflecting from these areas so we’re pretty sure that there’s water ice buried underneath,” said co-author Dr. Matthew Siegler, a JPL researcher and recent UCLA alumnus. “You need some kind of insulating layer to keep that heat from getting down to the ice.”
The presence of bright ice and dark organics on Mercury’s surface presents a mystery for MESSENGER researchers. Large comets and asteroids periodically impact Mercury, covering a huge swath of the planet in a layer of dirt and dust and adding yet another crater to the airless planet’s scarred landscape. For the water ice and black organic layers to remain exposed on Mercury’s ancient surface, the deposits must have formed recently in Mercury’s geological history or must be maintained by new water brought to Mercury by smaller, more frequent impacts.
“Billions of years ago, the Earth acquired a layer of water and other volatile material that formed atmospheres, oceans, and even the first organic molecules that started life,” said Paige. “Understanding the origin of that material is a very important problem and is essential to finding out about the potential habitability of planetary systems around other stars.”
Other UCLA co-authors include Ellen Harju, a graduate student in the department of Earth and space sciences. Paige’s study was published alongside two other MESSENGER papers with colleagues David Lawrence and Greg Neumann as the lead authors. All three research discoveries were showcased today in a press conference on NASA TV.
Launched in 2004, MESSENGER became the first spacecraft to orbit Mercury in March of 2011. Previously, humankind’s closest glimpse of the innermost planet in the solar system was during three flybys of Mercury by the Mariner 10 spacecraft in 1974–75. The name MESSENGER, short for MErcury Surface, Space ENvironment, GEochemistry and Ranging, was chosen to evoke the Greco-Roman messenger deity Mercury, a god of trade, merchants, and travel.
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Professor David Paige explains how a thermal model at UCLA helped determine where water ice is found on Mercury.
Professor David Paige discusses how water ice may have arrived on Mercury and the origin of mysterious dark material measured by MESSENGER.
Professor David Paige explains why studying ice on Mercury is important for understanding the origin of life on Earth and the potential habitability of extrasolar planets.
The online version of the print edition (published on January 17, 2013) is available here. And don’t forget to learn how David Paige crafted the cover of Science magazine to showcase the recent MESSENGER discoveries.
Post-doctoral scholar David Cebron will give a special seminar Thursday, November 29th, at 2pm in Geology 3814. The talk is entitled “Inertial waves & instabilities in planetary and stellar fluid interiors.”
Most astrophysical bodies such as gaseous planets, stars or the Earth liquid core are rapidly rotating fluids which allow the propagation of inertial waves. These waves are excited by natural mechanical forcings (tides, precession, libration) always present in such systems. Forcings can excite one particular wave (direct resonance) or can couple waves via parametric resonances called inertial instabilities. These vigorous flows may play an important role for the heat transport or can be an alternative to the classical thermo-chemical model for the generation of planetary and stellar magnetic fields (dynamo effect).
After an introduction on the geo-/astrophysical context of these inertial waves, he will focus on tidal forcing and present numerical simulations of the elliptical instability in an ellipsoidal geometry. Then, he will describe the influence of different natural complexities such as the oblateness, the presence of convective or stratified flows. He will also show that libration of sychronized bodies (e.g. the Earth-Moon system) can similarly lead to resonances of inertial waves. Finally, He will consider the possible role of these resonances in magnetic field generation (dynamo effect) using MHD simulations, and he will present the first free-surface simulations (SPH code, Gerris code) dedicated to the study of these flows in gaseous bodies.
The UCLA Department of Earth and Space Sciences will be hosting its annual lecture, “Focusing the search for biosignatures on Mars”.
The lecture will be held on Wednesday, November 28, 2012 in the Sequoia Room at the UCLA Faculty Center. The reception will begin at 5:30pm followed by the lecture at 7pm.
Researcher Dorothy Oehler (M.S. ’67, Ph.D. ’73) is a planetary geologist and Precambrian paleontologist at Johnson Space Center (JSC). She is interested in finding ways to identify the biosignatures of potential extraterrestrial life, and is currently working to establish new criteria for identifying the presence of primitive life form remnants. Oehler brings her search to Mars by using geological data to identify habitable sites on the planet where fragments of ancient Martian life may have been preserved.
For years, many scientists had thought that plate tectonics existed nowhere in our solar system but on Earth. Now, a UCLA scientist has discovered that the geological phenomenon, which involves the movement of huge crustal plates beneath a planet’s surface, also exists on Mars.
“Mars is at a primitive stage of plate tectonics. It gives us a glimpse of how the early Earth may have looked and may help us understand how plate tectonics began on Earth,” said An Yin, a UCLA professor of Earth and space sciences and the sole author of the new research.
Professor Ed Young of the Department of Earth & Space Sciences at UCLA was recently named a Fellow of the Meteoritical Society, an international organization dedicated to research and education on meteorites and other extraterrestrial materials.
To read more about this honor and the Meteoritical Society, click here.
To read more about Professor Young’s research, click here.
Global topographic map of Mars and location of Valles Marineris.
By Ivy S. Carpenter
A giant gash scars the surface of Mars. Known as Valles Marineris, it is one of the largest and most recognizable topographic features in our solar system. Boasting a whopping 4000-km length and a depth ranging from 10 – 15 km, it easily dwarfs Earth’s Grand Canyon (which is a piddling 2 km deep). But despite the distinction of being the longest trough system in the solar system, its origin and formation remain enigmatic.
In a new study selected as Editor’s Choice in the 2012 June 29th issue of Science and to be published in Lithosphere, UCLA’s Professor An Yin suggests that the current structure of the solar system’s ‘grandest canyon’ is a result of left-lateral transtensional faulting, similar to that found in Earth’s Dead Sea fault system.
A three-dimensional structural model for southern Valles Marineris. Notice that the fault zone consists of multiple faults, and the trough bounded on one side by a normal fault and the other side by a strike slip fault. Circles with dots indicate motion toward the viewer, circles with an X indicate motion away from the viewer.
In his model, transtensional deformation (a result of mixed lateral and extensional movement) occurs as a zone of both strike-slip (horizontal ground motion) and normal (vertical motion) faults. The normal faults allow for the subsidence and subsequent infill of a deep trough area, while strike-slip faults offset these sediments and underlying rock.
In a geological mapping tour-de-force, Yin used high-resolution data from NASA’s Mars Reconnaissance Orbiter and Mars Odyssey spacecraft to define the shapes, orientations, and cross-cutting relationships of surface structures such as landslides, erosion, impact features, strata, marker beds and folds in the southern end of the trough.
The results of the mapping effort show impressive trough-parallel left-slip offsets of 150-160 km throughout the Ius-Melas-Coprates fault zone. Offsets are seen clearly where numerous landslide deposits have been displaced sideways by ground motions (see image below). At a larger-scale, Yin identified a continuous, long (>2000 km) and narrow (<50 km) strike-slip zone with >100 km in total slip that appears strikingly similar to the undisputed plate boundary of the Earth’s Dead Sea fault zone. Some local trough-bounding faults may still be active, as they are seen to cut recent surface deposits and landslides.
(A) Image showing two landslides whose channels and fans have been offset by left-lateral strike slip motion. (B) Restored landslide postions after matching up the edges of the channels with their fans.
An alternate interpretation made recently by Jeffrey Andrews-Hannah of the Colorado School of Mines proposes that Marineris is a subsidence feature that formed as a result of the uplift of the nearby Tharsis bulge (see Andrews-Hanna, J.C. 2012., JGR, 117, E06002 at www.agu.org/pubs). However, Andrews-Hannah’s model does not easily account for the physical evidence of horizontal as well as vertical motion in the trough. The scientific debate has already been highlighted by several sources even before Yin’s paper has been published.
Yin’s study raises the fascinating question of why a planet that has supposedly not had plate tectonics for the past 4 billion years should show a feature that looks convincingly like a plate boundary. Vast areas of Valles Marineris, not to mention the other 143,998,500 square kilometers of Mars’ surface, remain imperfectly explored. Accordingly, there remains huge potential for what geological observations may tell us about the structure of this and other planets in the future.
The UCLA Institute for Planets and Exoplanets, The UK Center for Astrobiology and the NASA Astrobiology Institute held a meeting on campus last week where planetary scientists from around the world discussed their research determining the present-day habitability of Mars. While the conference has concluded, the talks were recorded and can be streamed publicly online here.
The latest issue of Science magazine features the discovery of 
