NASA Announces 2011 Carl Sagan Fellows

The Sagan Fellowship program, named after the late Carl Sagan, supports talented young scientists in their mission to explore the unknown. Following the path laid out by Sagan, these bright fellows will continue to tread the path, make their own discoveries and inspire future Sagan fellows.

NASA has selected five potential discoverers as the recipients of the 2011 Carl Sagan Postdoctoral Fellowships, named after the late astronomer. The Carl Sagan Fellowship takes a theme-based approach, in which fellows will focus on compelling scientific questions, such as "Are there Earth-like planets orbiting other stars?"

Sagan once said, "Somewhere, something incredible is waiting to be known," which is in line with the Sagan Fellowship's primary goal: to discover and characterize planetary systems and Earth-like planets around other stars. Planets outside of our solar system are called exoplanets. The fellowship also aims to support outstanding recent postdoctoral scientists in conducting independent research broadly related to the science goals of NASA's Exoplanet Exploration Program.

Previous Sagan Fellows have contributed significant discoveries in exoplanet exploration. including: the first characterizations of a super-Earth's atmosphere using a ground-based telescope; and the discovery of a massive disk of dust and gas encircling a giant young star, which could potentially answer the long-standing question of how massive stars are born.

"The Sagan Fellowship program seeks to identify the most highly qualified young researchers in the field of exoplanets. Nowhere is the dynamism of this young branch of astronomy demonstrated more dramatically than by the intellectual quality and enthusiasm of these five new Sagan Fellows," said Charles Beichman, executive director of the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena. "These scientists are certain to be leaders of this exciting and rapidly growing field for many years to come."

The program, created in 2008, awards selected postdoctoral scientists with annual stipends of approximately $64,500 for up to three years, plus an annual research budget of up to $16,000. Topics range from techniques for detecting the glow of a dim planet in the blinding glare of its host star, to searching for the crucial ingredients of life in other planetary systems.

The 2011 Sagan Fellows are:

-- David Kipping, who will work at the Harvard-Smithsonian Center for Astrophysics, Cambridge, to combine theory and observation to conduct a search for the moons of exoplanets.

-- Bryce Croll, who will work at the Massachusetts Institute of Technology, Cambridge, Mass., to characterize the atmospheres of both large and small exoplanets using a variety of telescopes.

-- Wladimir Lyra, who will work at NASA's Jet Propulsion Laboratory, Pasadena, Calif., to study planet-forming disks and exoplanet formation.

-- Katie Morzinski, who will work at the University of Arizona, Tucson, to commission and employ high-contrast adaptive optics systems that will directly image Jupiter-like exoplanets.

-- Sloane Wiktorowicz, who will work at the University of California, Santa Cruz to use a technique called optical polarimetry to directly detect exoplanets.

NASA has two other astrophysics theme-based fellowship programs: the Einstein Fellowship Program, which supports research into the physics of the cosmos, and the Hubble Fellowship Program, which supports research into cosmic origins. The Sagan Fellowship Program is administered by the NASA Exoplanet Science Institute as part of NASA's Exoplanet Exploration Program at JPL in Pasadena, Calif. The California Institute of Technology manages JPL for NASA.

A full description of the 2011 fellows and their projects, and other information about these programs is available at: http://nexsci.caltech.edu/sagan/2011postdocRecipients.shtml .

More information about NASA's Astrophysics Division is at: http://nasascience.nasa.gov/astrophysics .

When is an Asteroid Not an Asteroid?

This image shows a model of the protoplanet Vesta, using scientists' best guess to date of what the surface of the protoplanet might look like. › Full image and caption

On March 29, 1807, German astronomer Heinrich Wilhelm Olbers spotted Vesta as a pinprick of light in the sky. Two hundred and four years later, as NASA's Dawn spacecraft prepares to begin orbiting this intriguing world, scientists now know how special this world is, even if there has been some debate on how to classify it.

Vesta is most commonly called an asteroid because it lies in the orbiting rubble patch known as the main asteroid belt between Mars and Jupiter. But the vast majority of objects in the main belt are lightweights, 100-kilometers-wide (about 60-miles wide) or smaller, compared with Vesta, which is about 530 kilometers (330 miles) across on average. In fact, numerous bits of Vesta ejected by collisions with other objects have been identified in the main belt.

"I don't think Vesta should be called an asteroid," said Tom McCord, a Dawn co-investigator based at the Bear Fight Institute, Winthrop, Wash. "Not only is Vesta so much larger, but it's an evolved object, unlike most things we call asteroids."

The layered structure of Vesta (core, mantle and crust) is the key trait that makes Vesta more like planets such as Earth, Venus and Mars than the other asteroids, McCord said. Like the planets, Vesta had sufficient radioactive material inside when it coalesced, releasing heat that melted rock and enabled lighter layers to float to the outside. Scientists call this process differentiation.

McCord and colleagues were the first to discover that Vesta was likely differentiated when special detectors on their telescopes in 1972 picked up the signature of basalt. That meant that the body had to have melted at one time.

Officially, Vesta is a "minor planet" -- a body that orbits the sun but is not a proper planet or comet. But there are more than 540,000 minor planets in our solar system, so the label doesn't give Vesta much distinction. Dwarf planets – which include Dawn's second destination, Ceres -- are another category, but Vesta doesn't qualify as one of those. For one thing, Vesta isn't quite large enough.

Dawn scientists prefer to think of Vesta as a protoplanet because it is a dense, layered body that orbits the sun and began in the same fashion as Mercury, Venus, Earth and Mars, but somehow never fully developed. In the swinging early history of the solar system, objects became planets by merging with other Vesta-sized objects. But Vesta never found a partner during the big dance, and the critical time passed. It may have had to do with the nearby presence of Jupiter, the neighborhood's gravitational superpower, disturbing the orbits of objects and hogging the dance partners.

Other space rocks have collided with Vesta and knocked off bits of it. Those became debris in the asteroid belt known as Vestoids, and even hundreds of meteorites that have ended up on Earth. But Vesta never collided with something of sufficient size to disrupt it, and it remained intact. As a result, Vesta is a time capsule from that earlier era.

"This gritty little protoplanet has survived bombardment in the asteroid belt for over 4.5 billion years, making its surface possibly the oldest planetary surface in the solar system," said Christopher Russell, Dawn's principal investigator, based at UCLA. "Studying Vesta will enable us to write a much better history of the solar system's turbulent youth."

Dawn's scientists and engineers have designed a master plan to investigate these special features of Vesta. When Dawn arrives at Vesta in July, the south pole will be in full sunlight, giving scientists a clear view of a huge crater at the south pole. That crater may reveal the layer cake of materials inside Vesta that will tell us how the body evolved after formation. The orbit design allows Dawn to map new terrain as the seasons progress over its 12-month visit. The spacecraft will make many measurements, including high-resolution data on surface composition, topography and texture. The spacecraft will also measure the tug of Vesta's gravity to learn more about its internal structure.

"Dawn's ion thrusters are gently carrying us toward Vesta, and the spacecraft is getting ready for its big year of exploration," said Marc Rayman, Dawn's chief engineer at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We have designed our mission to get the most out of this opportunity to reveal the exciting secrets of this uncharted, exotic world."

The Dawn mission to Vesta and Ceres is managed by the Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate, Washington. The Dawn mission is part of the Discovery Program managed by NASA's Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science. Orbital Sciences Corporation of Dulles, Va., designed and built the Dawn spacecraft. The German Aerospace Center, the Max Planck Society, the Italian Space Agency and the Italian National Astrophysical Institute are part of the mission team.

For more information about Dawn, visit http://www.nasa.gov/dawn and http://dawn.jpl.nasa.gov .

Future Engineers Unite at Robotics Competition

The 20th season of the Los Angeles regional FIRST (For Inspiration and Recognition of Science and Technology) Robotics Competition, held at the Long Beach Convention Center, March 25 and 26, proved to be a fierce competition between 63 high school teams from across California and as far away as Chile.

Students from three California schools – South High School, Torrance; West Covina High School, West Covina; and Diamond Bar High School, Diamond Bar, won the overall regional competition. Two other California schools also took top honors. Chaminade College Preparatory, West Hills, receied the coveted Regional Chairman's award, while Foshay Learning Center, Los Angeles, a team mentored by NASA's Jet Propulsion Laboratory in Pasadena, Calif., took home the Engineering Inspiration award.

The winners will represent the California region at the FIRST championships April 27 to 30 in St. Louis, where they will compete against 51,000 other students on more than 2,000 teams.

The FIRST program was founded two decades ago to encourage students to pursue careers in science and technology through robotics competitions. With the help of engineers from JPL, aerospace and other companies and institutions of higher education, FIRST continues to grow and inspire students.

For more information, visit: http://www.usfirst.org/ .

NASA Finds Polar Ice Adding More to Rising Seas

Store Glacier, West Greenland. A new NASA funded study finds that the Greenland and Antarctic ice sheets are losing mass at an accelerating pace, three times faster than that of mountain glaciers and ice caps. › Full image and caption

The Greenland and Antarctic ice sheets are losing mass at an accelerating pace, according to a new NASA-funded satellite study. The findings of the study -- the longest to date of changes in polar ice sheet mass -- suggest these ice sheets are overtaking ice loss from Earth's mountain glaciers and ice caps to become the dominant contributor to global sea level rise, much sooner than model forecasts have predicted.

The nearly 20-year study reveals that in 2006, a year in which comparable results for mass loss in mountain glaciers and ice caps are available from a separate study conducted using other methods, the Greenland and Antarctic ice sheets lost a combined mass of 475 gigatonnes a year on average. That's enough to raise global sea level by an average of 1.3 millimeters (.05 inches) a year. (A gigatonne is one billion metric tons, or more than 2.2 trillion pounds.)

The pace at which the polar ice sheets are losing mass was found to be accelerating rapidly. Each year over the course of the study, the two ice sheets lost a combined average of 36.3 gigatonnes more than they did the year before. In comparison, the 2006 study of mountain glaciers and ice caps estimated their loss at 402 gigatonnes a year on average, with a year-over-year acceleration rate three times smaller than that of the ice sheets.

"That ice sheets will dominate future sea level rise is not surprising -- they hold a lot more ice mass than mountain glaciers," said lead author Eric Rignot, jointly of NASA's Jet Propulsion Laboratory, Pasadena, Calif., and the University of California, Irvine. "What is surprising is this increased contribution by the ice sheets is already happening. If present trends continue, sea level is likely to be significantly higher than levels projected by the United Nations Intergovernmental Panel on Climate Change in 2007. Our study helps reduce uncertainties in near-term projections of sea level rise."

Rignot's team combined nearly two decades (1992-2009) of monthly satellite measurements with advanced regional atmospheric climate model data to examine changes in ice sheet mass and trends in acceleration of ice loss.

The study compared two independent measurement techniques. The first characterized the difference between two sets of data: interferometric synthetic aperture radar data from European, Canadian and Japanese satellites and radio echo soundings, which were used to measure ice exiting the ice sheets; and regional atmospheric climate model data from Utrecht University, The Netherlands, used to quantify ice being added to the ice sheets. The other technique used eight years of data from the NASA/German Aerospace Center's Gravity Recovery and Climate Experiment (Grace) satellites, which track minute changes in Earth's gravity field due to changes in Earth's mass distribution, including ice movement.

The team reconciled the differences between techniques and found them to be in agreement, both for total amount and rate of mass loss, over their data sets' eight-year overlapping period. This validated the data sets, establishing a consistent record of ice mass changes since 1992.

The team found that for each year over the 18-year study, the Greenland ice sheet lost mass faster than it did the year before, by an average of 21.9 gigatonnes a year. In Antarctica, the year-over-year speedup in ice mass lost averaged 14.5 gigatonnes.

"These are two totally independent techniques, so it is a major achievement that the results agree so well," said co-author Isabella Velicogna, also jointly with JPL and UC Irvine. "It demonstrates the tremendous progress that's being made in estimating how much ice the ice sheets are gaining and losing, and in analyzing Grace's time-variable gravity data."

The authors conclude that, if current ice sheet melting rates continue for the next four decades, their cumulative loss could raise sea level by 15 centimeters (5.9 inches) by 2050. When this is added to the predicted sea level contribution of 8 centimeters (3.1 inches) from glacial ice caps and 9 centimeters (3.5 inches) from ocean thermal expansion, total sea level rise could reach 32 centimeters (12.6 inches). While this provides one indication of the potential contribution ice sheets could make to sea level in the coming century, the authors caution that considerable uncertainties remain in estimating future ice loss acceleration.

Study results are published this month in Geophysical Research Letters. Other participating institutions include the Institute for Marine and Atmospheric Research, Utrecht University, The Netherlands; and the National Center for Atmospheric Research, Boulder, Colo.

JPL developed Grace and manages the mission for NASA. The University of Texas Center for Space Research in Austin has overall mission responsibility. GeoForschungsZentrum Potsdam (GFZ), Potsdam, Germany, is responsible for German mission elements.

More on Grace is online at http://www.csr.utexas.edu/grace/ and http://grace.jpl.nasa.gov/ .