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Monthly Archives: December 2009

Saturn’s Titan Splash

Last week there was a big splash (pun intended) made over some images taken by the Cassini spacecraft of Titan, Saturn’s largest moon. The images suggest that there is indeed liquid (liquid does not mean liquid water) on the surface of Titan. NASA has an excellent summary of the interpretation of the images online here, but please keep in mind that water has a number of unique properties. One of them is that water freezes from the top down, because frozen water floats in the liquid phase of water. Thus, here on Earth you can have frozen ponds with fish still swimming beneath. And on Europa you may find liquid water beneath the frozen solid surface top. Liquid ethane and methane don’t act in the same manner.

SS433 Still Something of an Enigma

In a paper to be published in the Astrophysical Journal, available online now here, astronomers re-examine an old friend called SS433. As the authors put it “SS 433 has been studied for about 30 years since its discovery, the identification of the compact object, the most fundamental issue to understand this system, has remained unsolved.” With the help of the Subaru and Gemini satellites, these astronomers believe that they have better constrained the mass of SS433 to be between 1.9 and 4.9 solar masses. Nonetheless, these astronomers hedge their bets and still won’t state definitively that SS433 is indeed a black hole. And so the SS433 saga continues.

Understanding Saturn’s Ring System

As the authors put it, “the origin and long-term evolution of Saturn’s rings is still an unsolved problem.” While astronomers still seek answers to many of the questions about Saturn’s ring system, the Cassini spacecraft has been a tremendous help in approaching the answers. In a recently released book titled “Saturn from Cassini-Huygen”, one chapter is devoted to to Saturn’s rings, and is now available online here. So take a look if you ever wondered where Saturn got its rings.

Massive Black Holes Got Gas

In a paper submitted to the Monthly Notices of the Royal Astronomical Society, available online now here, astronomers from UC Berkeley discuss their computer simulations of the gas in the vicinity of massive black holes in the core of galaxies. Of note are the conclusions that black hole accretion rates and star formation rates are correlated, thus linking star formation rates to the active galactic nuclei (AGN) of galaxies. And if you are not impressed by those conclusions, perhaps you’ll be impressed by the movies developed by the computer simulations, which are available online here.

Latest Results from Cryogenic Dark Matter Search

The Cryogenic Dark Matter Search (CDMS) is a collaborative effort among 15 universities. The experiment is being conducted “a half-mile underground at the Soudan mine in northern Minnesota,” and it “uses 30 detectors made of germanium and silicon in an attempt to detect” what is known as WIMPs. WIMPs are Weakly Interacting Massive Particles which are suspected as being a major contributor to the dark matter in the universe. The announcement summarizing the latest results from CDMS can be found here. For a more technical description of the results, check out the pre-publication paper available online now here. Very briefly, while CDMS has detected two possible dark matter WIMP events, the probability that these detections are from background noise is such that the CDMS team is not going to say that it has been a successful detection. Nonetheless, as the experiment continues, these data provide some hope to astronomers in their attempt to characterize the nature of the cold dark matter that apparently engulfs all galaxies.

Kuiper Belt Grows in Hubble’s View

The Hubble Space Telescope (HST) has been valuable in the search for solar system objects — including worldlets well beyond the orbit of Neptune. This region is called the Kuiper Belt and it’s a vast ring of icy debris. Material in this debris ranges from dust-sized particles up to objects the size of miniature worlds — the so-called Kuiper Belt Objects (KBOs).

Recently, scientists studying archived HST pointing system data found the telltale signature of a tiny KBO that lies some 6.7 billion kilometers (4.2 billion miles) from Earth.  At roughly 975 meters (3,200 feet) across, it is the smallest KBO ever found.  It is also the first observational evidence for a population of comet-sized bodies in the Kuiper Belt that are being ground down by collisions.  What this means is that icy debris particles  in this part of the solar system collide and break apart. This results in changes in the population of objects in the Kuiper Belt. These changes can be as simple as cracks and craters or involve more complex processes like heating and melting, which alters the chemical composition of the objects. Thus, over the course of 4.56 billion years, the Kuiper Belt has evolved quite a bit from its “pristine” state, right after the formation of the Solar System.

Studying this region also has implications for the study of such rings around other stars, something ELSE that Hubble does very well. Its observations of nearby stars show that a number of them have Kuiper Belt-like disks of icy debris encircling them. These disks are the remnants of planetary formation, just as our own KBO is the icy repository of material left over after the Sun and planets formed more than 4.5 billion years ago. Studying our own and distant KBO populations help scientists understand the evolutionary history of planetary systems, particularly such icy debris disks. For these distant stars, Hubble scientists predict that over billions of years the debris should collide, grinding the KBO-type objects down to ever smaller pieces that were not part of the original debris population. For more information on this discovery, visit the news announcement about it at the Hubble Space Telescope web site page.

NASA Partners with Saudi Arabia on Moon and Asteroid Research

NASA Press Release

 

WASHINGTON — NASA and the Kingdom of Saudi Arabia’s King Abdulaziz City for Science and Technology (KACST) have signed a joint statement that allows for collaboration in lunar and asteroid science research. The partnership recognizes the Saudi Lunar and Near-Earth Object Science Center as an affiliate partner with the NASA Lunar Science Institute at NASA’s Ames Research Center in Moffett Field, Calif.

“This collaboration is within the scope of the Memorandum of Understanding on Science and Technology signed between the Kingdom of Saudi Arabia and the United States of America last year and later ratified by the Council of Ministers,” said H.H. Dr. Turki Bin Saud Bin Mohammed Al-Saud, vice president for Research Institutes, KACST. “The international interest in lunar science and, more recently, near Earth objects led to the establishment of the Saudi Lunar and Near Earth Object Science Center as a focal point for lunar science and NEO studies in the Kingdom of Saudi Arabia. Furthermore, we are looking forward to our expanding collaboration with NASA for the benefit of both countries.”

“NASA’s Lunar Science Institute exists to conduct cutting-edge lunar science and train the next generation of lunar scientists and explorers,” said Greg Schmidt, institute deputy director at Ames. “Our international partnerships are critical for meeting these objectives, and we are very excited by the important science, training and education that our new Saudi colleagues bring to the NASA Lunar Science Institute.”

“This is an important advance in our growing program of bilateral science and technology cooperation,” said U.S. Ambassador to Saudi Arabia James Smith. “It will help realize President Obama’s goal, expressed in his June 4 speech to the Muslim world, of increasing our cooperation on science and technology, which we believe closely corresponds to King Abdullah’s vision.”

The Saudi science center’s proposal brings technical and engineering expertise to advance the broad goals of lunar science at the institute. Specific areas of lunar study of both scientific and cultural importance include radar and infrared imaging, laser ranging and imaging, and topographical studies. The center’s studies in near-Earth object science also offer important contributions to an area of importance to NASA.

“The Saudi Lunar and Near Earth Object Science Center’s primary mission is to direct all lunar and near Earth object related research within the Kingdom of Saudi Arabia,” said Dr. Haithem Altwaijry, deputy director of the National Satellite Technology Program at KACST. “It will reach out to students in addition to researchers and present fertile ground for scientific research.”

“NASA welcomes international cooperation for mutual benefit with organizations large and small in all regions of the world,” said Michael O’Brien, assistant administrator for external relations at NASA Headquarters in Washington. “Our continuing discussions with Saudi Arabian officials may lead to future joint scientific collaboration in other areas of mutual interest.”

To learn more about the NASA Lunar Science Institute visit:

 

 

http://lunarscience.nasa.gov

NASA’s WISE Eye on the Universe Begins All-Sky Survey Mission

NASA Press Release

VANDENBERG AIR FORCE BASE, Calif. — NASA’s Wide-field Infrared Survey Explorer, or WISE, lifted off over the Pacific Ocean this morning on its way to map the entire sky in infrared light.

A Delta II rocket carrying the spacecraft launched at 6:09 a.m. PST (9:09 a.m. EST) from Vandenberg Air Force Base in California. The rocket deposited WISE into a polar orbit 326 miles above Earth.

“WISE thundered overhead, lighting up the pre-dawn skies,” said William Irace, the mission’s project manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “All systems are looking good, and we are on our way to seeing the entire infrared sky better than ever before.”

Engineers acquired a signal from the spacecraft via NASA’s Tracking and Data Relay Satellite System just 10 seconds after the spacecraft separated from the rocket. Approximately three minutes later, WISE re-oriented itself with its solar panels facing the sun to generate its own power. The next major event occurred about 17 minutes later. Valves on the cryostat, a chamber of super-cold hydrogen ice that cools the WISE instrument, opened. Because the instrument sees the infrared, or heat, signatures of objects, it must be kept at chilly temperatures. Its coldest detectors are less than minus 447 degrees Fahrenheit.

“WISE needs to be colder than the objects it’s observing,” said Ned Wright of UCLA, the mission’s principal investigator. “Now we’re ready to see the infrared glow from hundreds of thousands of asteroids, and hundreds of millions of stars and galaxies.”

With the spacecraft stable, cold and communicating with mission controllers at JPL, a month-long checkout and calibration is underway.

WISE will see the infrared colors of the whole sky with sensitivity and resolution far better than the last infrared sky survey, performed 26 years ago. The space telescope will spend nine months scanning the sky once, then one-half the sky a second time. The primary mission will end when WISE’s frozen hydrogen runs out, about 10 months after launch.

Just about everything in the universe glows in infrared, which means the mission will catalog a variety of astronomical targets. Near-Earth asteroids, stars, planet-forming disks and distant galaxies all will be easy for the mission to see. Hundreds of millions of objects will populate the WISE atlas, providing astronomers and other space missions, such as NASA’s planned James Webb Space Telescope, with a long-lasting infrared roadmap.

JPL manages the Wide-field Infrared Survey Explorer for NASA’s Science Mission Directorate in Washington. The mission was competitively selected under the Explorers Program, managed by NASA’s Goddard Space Flight Center in Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory in Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp. in Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. NASA’s Launch Services Program at NASA’s Kennedy Space Center, Fla., managed the payload integration and the launch service.

More information about the WISE mission is available online at: http://www.nasa.gov/wise, http://wise.astro.ucla.edu and http://www.jpl.nasa.gov/wise.

More Authors More Citations

In an upublished study, available online here, Dr. Stanek of Ohio State University, has come to the conclusion that those published astronomical papers with more authors, get cited more often. While not a very strong correlation, this study examined some 30,000 articles in refereed journals of astronomy, and was a follow-on to his initial study, which concluded that the longer a paper was, the more it was cited as well. Stanek’s paper is a fun read, and the author admittedly has “his tongue in cheek.”

Detecting Exoplanet Moons with Gravitational Microlensing

In a paper to be published in Astronomy and Astrophysics, available online now here, astronomers have concluded that exoplanetary moons should be detectable using orbiting satellite telescopes and a technique known as gravitational microlensing. This technique, a refinement of gravitational lensing, applies Einstein’s General Theory of Relativity and its curvature of space effect on the path that the light will follow. Although the technique has only been used to discover a very small percentage of the 430 or so known exoplanets, it apparently may be ultimately used to discover moons orbiting exoplanets, where the other techniques cannot accomplish this feat. The paper is provides the reader an excellent overview of gravitational lensing, gravitational microlensing and its link to the experiments done almost a century ago to first demonstrate that Einstein’s General Theory of Relativity was correct.

December 2009
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