SCIENTISTS TO TRACK AND CALIBRATE EUSO TELESCOPE PROTOTYPE IN CANADA
From the FMS Global News Desk of Jeanne Hambleton Released: 11-Aug-2014 Source: University of Alabama Huntsville
Newswise — HUNTSVILLE, Ala. (Aug. 11, 2014) – A graduate student at The University of Alabama in Huntsville (UAH) and also a scientist and an engineer from UAH are on the way to Canada to help calibrate a prototype cosmic ray telescope that has a 2017 International Space Station flight goal.
Center for Space Plasma and Aeronomic Research (CSPAR) graduate student Matthew Rodencal, Douglass Huie of the Rotorcraft Systems Engineering and Simulation Center (RSESC) and Dr. James Adams of CSPAR will use a graphical tracking system developed at UAH to position a helicopter directly under a stratospheric balloon carrying the a prototype of the Extreme Universe Space Observatory (EUSO) telescope on a moonless night over a remote area of Ontario Province, Canada.
EUSO is being developed for a flight on the International Space Station to record the luminous tracks left by extremely energetic cosmic rays when they strike the Earth’s atmosphere.
Currently, there are two EUSO prototypes. One is the ground-based prototype located at Telescope Array (EUSO-TA) experiment in Utah and the other is Balloon EUSO, the telescope to be flown this month on a stratospheric balloon at an altitude of approximately 120,000 feet. The UAH researchers are part of a team that will be calibrating Balloon EUSO during its flight over Canada.
The Global Light System (GLS) is being developed by UAH in collaboration with Marshall Space Flight Center (MSFC) and the Colorado School of Mines. UAH is contributing a xenon flash lamp and a light emitting diode flasher, both operating in the ultraviolet. The plan is to position these GLS units on high mountains around the Earth as ground calibration light sources for EUSO when it is flying on the space station.
Using the UAH-designed tracking device, Rodencal will assist the helicopter pilot to find the balloon and fly directly under it so that researchers from UAH and the Colorado School of Mines (CSM) are positioned within the field of view of the prototype EUSO telescope. Then they will use the flashers developed in CSPAR at UAH by Evgueni Kuznetsov and his student, Jurgen Sawatzki, and a laser-based calibration system developed by CSM to mimic the light from extremely energetic cosmic rays striking the Earth’s atmosphere.
“Cosmic rays are the highest energy particles in the universe,” Rodencal says. “When they reach the Earth, they interact with the atmosphere. This telescope is actually positioned to look down on the Earth. When the cosmic rays interact with the atmosphere, it captures a video clip of the track of light they create in the atmosphere. So it is not a camera in that it takes a pretty movie, it is more like the sensor that views a cosmic ray detector, which is the atmosphere of the Earth.”
The calibration instruments will duplicate fluorescent flashes produced by cosmic rays striking the atmosphere. UAH’s flashers simulate the light seen from a few-thousand-foot segment of a track caused by a cosmic ray coming straight down from space, while the CSM laser simulates the track of a cosmic ray traveling horizontally through the atmosphere.
“After the balloon is launched and gets to the correct altitude,” Rodencal says, “we are going to get underneath it in the helicopter retrofitted with both the UAH flashers and the high-powered laser and fire calibration pulses so that they can be recorded by the instrument on the balloon.”
The idea is to get the helicopter inside the field of view of the EUSO prototype that is looking down from the helicopter and then flash the flashers and fire the laser so the flashes can be recorded by the video camera, says Dr. Adams.
“We have calibrated the flashers so we know how bright they are,” Dr. Adams says. “We also know how much power there is in the laser beam so we can do a Rayleigh scattering calculation to see how bright the laser flash – which is fired horizontally – will look to the camera on the balloon. By measuring the flashers and the laser on the balloon we can see how bright they look to this video camera. This calibrates it so we can also know how bright other flashes are that the camera will record during the flight.”
The balloon will be launched from Timmins, Ontario, Canada, while the tracking and calibration helicopter will begin its mission from Ottawa.
“The balloon will fly west toward Thunder Bay,” Dr. Adams says. “We hope it will stay north of the border. The flight will last at least six hours beginning just before dark. If it stays far enough north, maybe it will fly until dawn.”
The UAH-CSM scientists have been practicing flying a helicopter under a balloon around Tullahoma, Tenn. Their last practice flight was last week.
ICEQUAKES IN ANTARCTICA
CHILEAN 2010 EARTHQUAKE CAUSES ICEQUAKES
From the FMS Global News Desk of Jeanne Hambleton Released: 11-Aug-2014
Source: Georgia Institute of Technology Citations Nature Geoscience
Newswise — Seismic events are not rare occurrences on Antarctica, where sections of the frozen desert can experience hundreds of micro-earthquakes an hour due to ice deformation. Some scientists call them icequakes. But in March of 2010, the ice sheets in Antarctica vibrated a bit more than usual because of something more than 3,000 miles away: the 8.8-magnitude Chilean earthquake. A new Georgia Institute of Technology study published in Nature Geoscience is the first to indicate that Antarctica’s frozen ground is sensitive to seismic waves from distant earthquakes.
To study the quake’s impact on Antarctica, the Georgia Tech team looked at seismic data from 42 stations in the six hours before and after the 3:34 a.m. event. The researchers used the same technology that allowed them to “hear” the seismic response at large distances for the devastating 2011 magnitude 9 Japan earthquake as it rumbled through the earth. In other words, they simply removed the longer-period signals as the seismic waves spread from the distant epicenter to identify high-frequency signals from nearby sources. Nearly 30 percent (12 of the 42 stations) showed clear evidence of high-frequency seismic signals as the surface-wave arrived on Antarctica.
“We interpret these events as small icequakes, most of which were triggered during or immediately after the passing of long-period Rayleigh waves generated from the Chilean mainshock,” said Zhigang Peng, an associate professor in the School of Earth and Atmospheric Sciences who led the study.
“This is somewhat different from the micro-earthquakes and tremor caused by both Love and Rayleigh-type surface waves that traditionally occur in other tectonically active regions thousands of miles from large earthquakes.
Peng says the subtle difference is that micro-earthquakes respond to both shearing and volumetric deformation from distant events. The newly found icequakes respond only to volumetric deformation.
“Such differences may be subtle, but they tell us that the mechanisms of these triggered icequakes and small earthquakes are different,” Peng added.
“One is more like cracking, while the other is like a shear slip event. It s similar to two hands passing each other.”
Some of the icequakes were quick bursts and over in less than one second. Others were long duration, tremor-like signals up to 10 seconds. They occurred in various parts of the continent, including seismic stations along the coast and near the South Pole.
The researchers found the clearest indication of induced high-frequency signals at station HOWD near the northwest corner of the Ellsworth Mountains. Short bursts occurred when the P wave hit the station, then continued again when the Rayleigh wave arrived. The triggered icequakes had very similar high waveform patterns, which indicates repeated failure at a single location, possibly by the opening of cracks.
Peng says the source locations of the icequakes are difficult to determine because there is not an extensive seismic network coverage in Antarctica.
“But at least some of the icequakes themselves create surface waves, so they are probably formed very close to the ice surface,” he added.
“While we cannot be certain, we suspect they simply reflect fracturing of ice in the near surface due to alternating volumetric compressions and expansions as the Rayleigh waves passed through Antarctica’s frozen ice.”
Antarctica was originally not on the research team’s target list. While examining seismic stations in the Southern Hemisphere, Peng “accidently” found the triggered icequakes at a few openly available stations. He and former Georgia Tech postdoctoral student Jake Walter (now a research scientist at the Institute for Geophysics at UT Austin) then reached out to other seismologists (the paper’s four co-authors) who were in charge of deploying more broadband seismometers in Antarctica.
This project is partially supported by a National Science Foundation CAREER grant (EAR-0956051). Any conclusions expressed are those of the principal investigator and may not necessarily represent the official views of the NSF.
A seismic station near Antarctica’s Ellsworth Mountains showed the clearest indication of high-frequency signals following the 2010 Chilean earthquake. High-frequency icequakes at station AGO (near the South Pole) in Antarctica during the distant waves of the 2010 magnitude 8.8 Chile earthquake. The triggered icequakes are indicated by the narrow vertical bands in the middle and lower sections of the graphic. They begin when the P wave arrives approximately 10 minutes (600 seconds) after the Chilean quake and continue through the arrival of the Rayleigh waves. The sound is generated by speeding up the AGO’s seismic data 100 times.
COMETS FORGE ORGANIC MOLECULES IN THEIR DUSTY ATMOSPHERES, ALMA CONFIRMS
From FMS Global News Desk of Jeanne Hambleton Released: 11-Aug-2014
Source Newsroom: National Radio Astronomy Observatory Citations Astrophysical Journal Letters
Newswise — An international team of scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) has made incredible 3D images of the ghostly atmospheres surrounding comets ISON and Lemmon. These new observations provided important insights into how and where comets forge new chemicals, including intriguing organic compounds.
Comets contain some of the oldest and most pristine materials in our Solar System. Understanding their unique chemistry could reveal much about the birth of our planet and the origin of organic compounds that are the building blocks of life. ALMA’s high-resolution observations provided a tantalizing 3D perspective of the distribution of the molecules within these two cometary atmospheres, or comas.
“We achieved truly first-of-a-kind mapping of important molecules that help us understand the nature of comets,” said team leader Martin Cordiner, a Catholic University of America astrochemist working at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The critical 3D component of the ALMA observations was made by combining high-resolution, two-dimensional images of the comets with high-resolution spectra obtained from three important organic molecules – hydrogen cyanide (HCN), hydrogen isocyanide (HNC), and formaldehyde (H2CO). These spectra were taken at every point in each image. They identified not only the molecules present but also their velocities, which provided the third dimension, indicating the depths of the cometary atmospheres.
The new results revealed that HCN gas flows outward from the nucleus quite evenly in all directions, whereas HNC is concentrated in clumps and jets. ALMA’s exquisite resolution could clearly resolve these clumps moving into different regions of the cometary comas on a day-to-day and even hour-to-hour basis. These distinctive patterns confirm that the HNC and H2CO molecules actually form within the coma and provide new evidence that HNC may be produced by the breakdown of large molecules or organic dust.
“Understanding organic dust is important, because such materials are more resistant to destruction during atmospheric entry, and some could have been delivered intact to the early Earth, thereby fueling the emergence of life,” said Michael Mumma, director of the Goddard Center for Astrobiology and a co-author on the study.
“These observations open a new window on this poorly known component of cometary organics.”
“So, not only does ALMA let us identify individual molecules in the coma, it also gives us the ability to map their locations with great sensitivity,” said Anthony Remijan, an astronomer with the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia, and a study co-author.
The observations, published today in the Astrophysical Journal Letters, were also significant because modest comets like Lemmon and ISON contain relatively low concentrations of these crucial molecules, making them difficult to probe in depth with Earth-based telescopes. The few comprehensive studies of this kind so far have been conducted on extremely bright comets, such as Hale-Bopp. The present results extend them to comets of only moderate brightness.
Comet ISON (formally known as C/2012 S1) was observed with ALMA on November 15-17, 2013, when it was only 75 million kilometers from the Sun (about half the distance of the Earth to the Sun). Comet Lemmon (formally known as C/2012 F6) was observed on June 1-2, 2013, when it was 224 million kilometers from the Sun (about 1.5 times the distance of the Earth to the Sun).
“The high sensitivity achieved in these studies paves the way for observations of perhaps hundreds of the dimmer or more distant comets,” said Goddard’s Stefanie Milam, a study co-author. “The findings suggest that it should also be possible to map more complex molecules that have so far eluded detection in comets.”
This research was funded by the NASA Astrobiology Institute through the Goddard Center for Astrobiology and by NASA’s Planetary Atmospheres and Planetary Astronomy programs.
The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Southern Observatory (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.
See you Wednesday, Jeanne