Nov 15 2012
From The Space Library
RELEASE: 12-397 NASA'S GREAT OBSERVATORIES FIND CANDIDATE FOR MOST DISTANT GALAXY
WASHINGTON -- By combining the power of NASA's Hubble and Spitzer space telescopes and one of nature's own natural "zoom lenses" in space, astronomers have set a new record for finding the most distant galaxy seen in the universe. The farthest galaxy appears as a diminutive blob that is only a tiny fraction of the size of our Milky Way galaxy. But it offers a peek back into a time when the universe was 3 percent of its present age of 13.7 billion years. The newly discovered galaxy, named MACS0647-JD, was observed 420 million years after the big bang, the theorized beginning of the universe. Its light has traveled 13.3 billion years to reach Earth. This find is the latest discovery from a program that uses natural zoom lenses to reveal distant galaxies in the early universe. The Cluster Lensing And Supernova Survey with Hubble (CLASH), an international group led by Marc Postman of the Space Telescope Science Institute in Baltimore, Md., is using massive galaxy clusters as cosmic telescopes to magnify distant galaxies behind them. This effect is called gravitational lensing. Along the way, 8 billion years into its journey, light from MACS0647-JD took a detour along multiple paths around the massive galaxy cluster MACS J0647+7015. Without the cluster's magnification powers, astronomers would not have seen this remote galaxy. Because of gravitational lensing, the CLASH research team was able to observe three magnified images of MACS0647-JD with the Hubble telescope. The cluster's gravity boosted the light from the faraway galaxy, making the images appear about eight, seven, and two times brighter than they otherwise would that enabled astronomers to detect the galaxy more efficiently and with greater confidence. "This cluster does what no manmade telescope can do," said Postman. "Without the magnification, it would require a Herculean effort to observe this galaxy." MACS0647-JD is so small it may be in the first steps of forming a larger galaxy. An analysis shows the galaxy is less than 600 light-years wide. Based on observations of somewhat closer galaxies, astronomers estimate that a typical galaxy of a similar age should be about 2,000 light-years wide. For comparison, the Large Magellanic Cloud, a dwarf galaxy companion to the Milky Way, is 14,000 light-years wide. Our Milky Way is 150,000 light-years across. "This object may be one of many building blocks of a galaxy," said the study's lead author, Dan Coe of the Space Telescope Science Institute. "Over the next 13 billion years, it may have dozens, hundreds, or even thousands of merging events with other galaxies and galaxy fragments." The galaxy was observed with 17 filters, spanning near-ultraviolet to near-infrared wavelengths, using Hubble's Wide Field Camera 3 (WFC3) and Advanced Camera for Surveys (ACS). Coe, a CLASH team member, discovered the galaxy in February while poring over a catalogue of thousands of gravitationally lensed objects found in Hubble observations of 17 clusters in the CLASH survey. But the galaxy appeared only in the two reddest filters. "So either MACS0647-JD is a very red object, only shining at red wavelengths, or it is extremely distant and its light has been 'redshifted' to these wavelengths, or some combination of the two," Coe said. "We considered this full range of possibilities." The CLASH team identified multiple images of eight galaxies lensed by the galaxy cluster. Their positions allowed the team to produce a map of the cluster's mass, which is primarily composed of dark matter. Dark matter is an invisible form of matter that makes up the bulk of the universe's mass. "It's like a big puzzle," said Coe. "We have to arrange the mass in the cluster so that it deflects the light of each galaxy to the positions observed." The team's analysis revealed that the cluster's mass distribution produced three lensed images of MACS0647-JD at the positions and relative brightness observed in the Hubble image. Coe and his collaborators spent months systematically ruling out these other alternative explanations for the object's identity, including red stars, brown dwarfs, and red (old or dusty) galaxies at intermediate distances from Earth. They concluded that a very distant galaxy was the correct explanation. The paper will appear in the Dec. 20 issue of The Astrophysical Journal. Redshift is a consequence of the expansion of space over cosmic time. Astronomers study the distant universe in near-infrared light because the expansion of space stretches ultraviolet and visible light from galaxies into infrared wavelengths. Coe estimates MACS0647-JD has a redshift of 11, the highest yet observed. Images of the galaxy at longer wavelengths obtained with the Spitzer Space Telescope played a key role in the analysis. If the object were intrinsically red, it would appear bright in the Spitzer images. Instead, the galaxy barely was detected, if at all, indicating its great distance. The research team plans to use Spitzer to obtain deeper observations of the galaxy, which should yield confident detections as well as estimates of the object's age and dust content. MACS0647-JD galaxy, however, may be too far away for any current telescope to confirm the distance based on spectroscopy, which spreads out an object's light into thousands of colors. Nevertheless, Coe is confident the fledgling galaxy is the new distance champion based on its unique colors and the research team's extensive analysis. "All three of the lensed galaxy images match fairly well and are in positions you would expect for a galaxy at that remote distance when you look at the predictions from our best lens models for this cluster," Coe said. The new distance champion is the second remote galaxy uncovered in the CLASH survey, a multi-wavelength census of 25 hefty galaxy clusters with Hubble's ACS and WFC3. Earlier this year, the CLASH team announced the discovery of a galaxy that existed when the universe was 490 million years old, 70 million years later than the new record-breaking galaxy. So far, the survey has completed observations for 20 of the 25 clusters. The team hopes to use Hubble to search for more dwarf galaxies at these early epochs. If these infant galaxies are numerous, then they could have provided the energy to burn off the fog of hydrogen that blanketed the universe, a process called re-ionization. Re-ionization ultimately made the universe transparent to light.
RELEASE: 12-401 STUDENTS CONDUCT LIVE CONVERSATION WITH ORBITING NASA ASTRONAUTS
WASHINGTON -- More than 9,500 student participants from the Student Spaceflight Experiments Program (SSEP) took part in a live video downlink with International Space Station Expedition 33 Commander Sunita Williams and Flight Engineer Kevin Ford. The long-distance conversation took place Thursday at the Smithsonian National Air and Space Museum in Washington. The event was co-hosted with the Department of Education and the National Center for Earth and Space Science Education (NCESSE) and was carried live on NASA Television. The downlink is an annual event held in honor of International Education Week, a joint initiative between the Department of State and the Department of Education that celebrates the benefits of international education and exchange. Approximately 130 students from D.C.'s Stuart-Hobson Middle School participated in-person in the Moving Beyond Earth Gallery at the museum. The rest of the students participated virtually from across the country. Selected students from both audiences had the opportunity to ask questions of Ford and Williams about life, work and research aboard the orbiting laboratory. Following the live Earth-to-station exchange, NASA Associate Administrator for Education and two-time space shuttle astronaut Leland Melvin gave a presentation and encouraged the students to study science, technology, engineering and mathematics (STEM). "You are the scientists, engineers and astronauts of tomorrow," Melvin said. "America's future of scientific research and space exploration is in your hands, and there's no better way to prepare yourselves for those grand adventures than to start pursuing a STEM career now." Jeff Goldstein, director of NCESSE, which sponsors the SSEP, also addressed the students and shared recent program highlights. SSEP is an on-orbit educational research opportunity that allows students to design and fly experiments to the space station through a collaboration with NanoRacks, LLC, which is working in partnership with NASA as part of using the space station as a national laboratory. Other participants in the education activities included Deputy Secretary of Education Anthony Miller, Smithsonian Assistant Secretary for Education and Access Claudine Brown, and Director of the National Air and Space Museum Gen. J.R. "Jack" Dailey. This in-flight education downlink is one in a series with educational organizations in the United States and abroad to improve STEM teaching and learning. It is an integral component of NASA's Teaching From Space education program, which promotes learning opportunities and builds partnerships with the education community using the unique environment of space and NASA's human spaceflight program.
RELEASE: 12-402 NASA ROVER PROVIDING NEW WEATHER AND RADIATION DATA ABOUT MARS
PASADENA, Calif. -- Observations of wind patterns and natural radiation patterns on Mars by NASA's Curiosity rover are helping scientists better understand the environment on the Red Planet's surface. Researchers using the car-sized mobile laboratory have identified transient whirlwinds, mapped winds in relation to slopes, tracked daily and seasonal changes in air pressure, and linked rhythmic changes in radiation to daily atmospheric changes. The knowledge being gained about these processes helps scientists interpret evidence about environmental changes on Mars might have led to conditions favorable for life. During the first 12 weeks after Curiosity landed in an area named Gale Crater, an international team of researchers analyzed data from more than 20 atmospheric events with at least one characteristic of a whirlwind recorded by the Rover Environmental Monitoring Station (REMS) instrument. Those characteristics can include a brief dip in air pressure, a change in wind direction, a change in wind speed, a rise in air temperature or a dip in ultraviolet light reaching the rover. Two of the events included all five characteristics. In many regions of Mars, dust-devil tracks and shadows have been seen from orbit, but those visual clues have not been seen in Gale Crater. One possibility is that vortex whirlwinds arise at Gale without lifting as much dust as they do elsewhere. "Dust in the atmosphere has a major role in shaping the climate on Mars," said Manuel de la Torre Juarez of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. He is the investigation scientist for REMS, which Spain provided for the mission. "The dust lifted by dust devils and dust storms warms the atmosphere." Dominant wind direction identified by REMS has surprised some researchers who expected slope effects to produce north-south winds. The rover is just north of a mountain called Mount Sharp. If air movement up and down the mountain's slope governed wind direction, dominant winds generally would be north-south. However, east-west winds appear to predominate. The rim of Gale Crater may be a factor. "With the crater rim slope to the north and Mount Sharp to the south, we may be seeing more of the wind blowing along the depression in between the two slopes, rather than up and down the slope of Mount Sharp," said Claire Newman, a REMS investigator at Ashima Research in Pasadena. "If we don't see a change in wind patterns as Curiosity heads up the slope of Mount Sharp -- that would be a surprise." REMS monitoring of air pressure has tracked both a seasonal increase and a daily rhythm. Neither was unexpected, but the details improve understanding of atmospheric cycles on present-day Mars, which helps with estimating how the cycles may have operated in the past. The seasonal increase results from tons of carbon dioxide, which had been frozen into a southern winter ice cap, returning into the atmosphere as southern spring turns to summer. The daily cycle of higher pressure in the morning and lower pressure in the evening results from daytime heating of the atmosphere by the sun. As morning works its way westward around the planet, so does a wave of heat-expanded atmosphere, known as a thermal tide. Effects of that atmospheric tide show up in data from Curiosity's Radiation Assessment Detector (RAD). This instrument monitors high-energy radiation considered to be a health risk to astronauts and a factor in whether microbes could survive on Mars' surface. "We see a definite pattern related to the daily thermal tides of the atmosphere," said RAD principal investigator Don Hassler of the Southwest Research Institute's Boulder, Colo., branch. "The atmosphere provides a level of shielding, and so charged-particle radiation is less when the atmosphere is thicker. Overall, Mars' atmosphere reduces the radiation dose compared to what we saw during the flight to Mars." The overall goal of NASA's Mars Science Laboratory mission is to use 10 instruments on Curiosity to assess whether areas inside Gale Crater ever offered a habitable environment for microbes. JPL manages the Mars Science Laboratory Project for NASA's Science Mission Directorate in Washington. JPL also built Curiosity.
