UCLA Planets 2013

Institute for Planets and Exoplanets Planets2013 - 2014 Edition iPLEX A Note from the Director UCLA’s Institute for Planets and Exoplanets (iPLEX) was founded in late 2011 with seed funding provided by Dean of Physical Sciences Joseph Rudnick and Vice Chancellor for Research James Economou. Our main goal is to establish UCLA as the best place in the world to study planets in all their diversity. We target both our planetary neighbors in the solar system and exoplanets found in orbit around other stars. Studies of planets and exoplanets are complementary. Examining exoplanets gives the context needed to properly interpret the content and layout of our solar system, while observing the near- by solar system provides the detailed knowledge we need to understand distant planets of other stars. As you will see from this booklet, iPLEX brings togeth- er experts from a wide range of backgrounds, studying a staggering variety of topics. This intellectual breadth distinguishes planetary science from most other endeav- ors. We use techniques ranging from laboratory studies of isotopes and meteorites to theoretical calculations, and collect data from the world’s largest ground-based telescopes and from spacecraft spread across the solar system. Planetary science captures the imagination and enthusiasm of UCLA students, some of whom are fea- tured in these pages. We are keen to develop untapped opportunities for expansion of planetary science in un- dergraduate and graduate programs, and to reach out to Cover: the wider world. Thermal model of the north polar region of Mercury. Recently discov- This booklet showcases only a small fraction of the ered permanently shadowed regions planet-related science underway at UCLA. within impact craters (blue) remain at temperatures low enough to harbor ice deposits. Read more on Page 4 David Jewitt iPLEX Director Centrifugal Science Scientists at UCLA’s SPINLab simulate planetary interiors with laboratory experiments Page 6 INSIDE Exploring Asteroids Life on Mars? Dawn researchers get a detailed look at the asteroid Researchers discuss water ac- Vesta tivity on Mars and if microbes Page 10 could survive there Page 30 Planet Snapshots The Gemini Planet Imager will allow astronomers to directly image planets around other stars Page 14 Stormy Titan Outreach Prof. Jonathan Mitchell at- Visitors participate in hands- tempts to predict weather on on science activities at the an- Saturn’s largest moon, Titan nual “Explore Your Universe” Page 18 event at UCLA Page 33 Planetary Geology Prof. An Yin applies his Earth Production Team geology background to other Ivy S. Curren planets Kim DeRose Page 22 Icy Mercury Surface temperatures on Mercury reveal extensive ice deposits in polar regions A map of surface temperatures at Mer- cury’s north pole. Purple and blue areas indicate locations where ice can exist on or below the surface. n a tour of water ice deposits in the solar and preserve water for billions of years. These “natural system, the planet Mercury would seem an freezers” exist within the shadowed areas of polar-crater unlikely stop. Twice as close to the Sun as rims, never experiencing direct sunlight due to the low Earth,O Mercury is constantly roasting at oven-like tem- angle of the Sun near the poles, Paige said. peratures. Nevertheless, scientists analyzing data from Paige, a self-described “professional ice finder,” has NASA’s MESSENGER spacecraft have confirmed earli- studied the poles of planetary bodies in the solar system er work showing that small areas in the polar regions of from Mercury all the way to Pluto. His most recent Mercury are able to escape the scorching sunlight and research, presented on NASA TV in November 2012, remain downright frigid. Using topographic data from sheds light on the long-standing issue of ice on Mercu- NASA’s MESSENGER mission, UCLA Professor David ry. In the early 1990s, scientists were surprised to find Paige and his team have crafted the first accurate com- areas near Mercury’s poles that were unusually bright puter model of temperatures at the poles of Mercury. when observed with radar from Earth, an indication They have successfully pinpointed extremely cold places that ice might be present on the scalding world. Paige’s near Mercury’s north pole where frozen water can be thermal model identified cold spots on Mercury, almost found on or below the surface. perfectly matching the locations where ice was inferred “Mercury is the innermost planet in the solar sys- from radar and MESSENGER observations. tem, and, arguably, it’s among the least explored,” said But ice was not the only substance MESSENGER Paige. “The surface exhibits the most extreme range scientists found on Mercury. Scientists were surprised of temperatures of any body we know of in the solar to find unusually dark deposits above polar ice within system.” Within a single polar crater on Mercury, there permanently shadowed craters. Paige believes these are spots that reach temperatures above 500 degrees newly discovered black deposits are a thin crust of Fahrenheit within sight of areas cold enough to freeze lingering organic material brought to the planet over 4 | UCLA Planets the past several million years by the impact of water-rich asteroids and comets. “The stuff we find covering the ice is darker than the rest of Mercury, which is already a really dark planet. That’s amazing,” Paige said. “At the very least, it means there is something out of the ordi- nary going on inside these permanently shadowed areas where the ice has accumulated.” Comets and asteroids periodi- cally crash into Mercury, bringing water ice and a diverse cocktail of organic material to the planet. In the searing daytime heat of Mercu- ry, the only place water and organics can survive without evaporating A surface temperature map of into space is within permanently shadowed craters at the poles. craters in the north polar region of In the warmest parts of the shadowed areas, the water evaporates Mercury. The two largest craters away, leaving behind the hardier organic molecules that stick are approximately 25 km in diam- around at higher temperatures. This organic coating becomes eter. Blue and purple areas are black when exposed at the surface, in some cases covering sub- cold enough to harbor surface or surface ice deposits and protecting them from evaporation. subsurface ice deposits. The presence of bright ice and dark organics on Mercury’s surface presents a mystery for MESSENGER scientists. Every time a large comet or asteroid collides with Mercury, a huge swath of the planet becomes covered in a layer of dirt and dust kicked up during the impact. For the water ice and black organic layers to have remained exposed as they appear today, the deposits must have either formed recently in the planet’s history or be maintained by new water brought to Mercury by smaller, more frequent impacts of icy bodies. Planetary scientists remain puzzled as to why the extensive water ice deposits have been preserved on Mercury while corre- sponding permanently shadowed regions on the Moon remain relatively dry. Paige, the principal investigator of the Diviner Lunar Radiometer experiment onboard NASA’s Lunar Recon- naissance Orbiter, created his thermal model of Mercury using data he has collected from the Moon. Since the crater-scarred landscapes of both bodies have comparable temperatures and conditions at the poles, one might expect the two bodies to have the same amount of ice. The large discrepancy remains a mystery that may only be solved through future research. Understanding how water ice and organics arrived on Mer- cury may help scientists determine the conditions necessary for sustaining life on other planets. “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,” Paige said. “Uncovering the origin of the surface material at the poles of Mercury is a very important problem. It is essential to understanding the origins of life and the potential habitability of planetary systems around other stars.” David Paige is a professor in the Earth and Space Sciences department. UCLA Planets | 5 Putting a spin on fluid dynamics Scientists from UCLA’s SPINLab simulate planetary interiors with rotating experiments he Simulated Planetary Interiors Laborato- fluid inside a planetary core.” “The idea is to study all the in- ry, known more fondly as the SPINLab, is gredients that are involved in planetary core convection and a state-of-the-art fluid dynamics research dynamo generation in their simplified state,” said Jonathan facilityT among only a handful of such unique labs in Cheng, a fourth-year graduate student with Aurnou. Dyna- the world. Funded by the National Science Founda- mos, large-scale magnetic fields generated from the motions tion, the group is led by Associate Professor Jonathan of an electrically conducting fluid, are known to exist within Aurnou, who has dedicated over ten years of his life planets, stars and even galaxies. Yet the detailed physics of to building functional models of planetary cores and these natural dynamos remain largely mysterious. atmospheres. The daily routine for Jon, his graduate students, post-doctoral scholars and researchers involves spinning large, heat-driven containers of water or liquid metal in order to understand the fundamental physics of rotating bodies. “We are interested in ex- plaining how strongly turbulent systems, like planetary cores and planetary atmospheres, organize into planetary-scale magnetic fields, jet systems, and vortices,” said Aurnou. The primary device used in the lab, a rotating magnetic convection device (RoMag), is a fluid-filled cylinder that to The SPINLab team. From Left to Right: Michael Le Bars, Alex Grannan, Jonathan Aurnou, Aurnou represents “a parcel of and Jonathan Cheng.

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