Thursday, April 19, 2012
Infrared and X-ray observations from two space telescopes have been combined to create a unique look at violent events within the giant galaxy Centaurus A. The observations strengthen the view that the galaxy may have been created by the cataclysmic collision of two older galaxies.
The infrared light was captured by the European Space Agency's Herschel Space Observatory, a mission with important NASA contributions. The X-ray observations were made by the European Space Agency's XMM-Newton space telescope.
Centaurus A is the closest giant elliptical galaxy to Earth, at a distance of around 12 million light-years. It stands out because it harbors a massive black hole at its core and emits intense blasts of radio waves.
While previous images taken in visible light hinted at the complex inner structure in Centaurus A, combining the output of two orbiting observatories working at almost opposite ends of the electromagnetic spectrum has revealed the unusual structure in much greater detail.
The galaxy was observed by astronomer Sir John Herschel in 1847 during his survey of the southern skies. Now, more than 160 years later, the observatory bearing his family name has played a unique role in uncovering some of its secrets.
With the Herschel observatory, the giant black scar of obscuring dust crossing the center of Centaurus A all but disappears when viewed at long infrared wavelengths. The images show the flattened inner disk of a spiral galaxy, the shape of which scientists believe is due to a collision with an elliptical galaxy during a past epoch.
The Herschel data also uncover evidence for intense star birth toward the center of the galaxy, along with two jets emanating from the galaxy's core -- one of them 15,000 light-years long. Newly discovered clouds co-aligned with the jets can also be seen in Herschel's view.
The XMM-Newton X-ray observatory recorded the high-energy glow from one of the jets, extending more than 12,000 light-years away from the galaxy's bright nucleus. XMM-Newton's view shows not only the way that the jet interacts with the surrounding interstellar matter, but also the galaxy's intensely active nucleus, and its large gaseous halo.
The jets seen by both satellites are evidence of the supermassive black hole --10 million times the mass of our sun -- at the center of the galaxy.
For more information visit http://www.nasa.gov/mission_pages/herschel/news/herschel20120404.html
Tuesday, April 10, 2012
Leaner, greener flying machines for the year 2025 are on the drawing boards of three industry teams under contract to the NASA Aeronautics Research Mission Directorate's Environmentally Responsible Aviation Project.
Teams from The Boeing Company in Huntington Beach, Calif., Lockheed Martin in Palmdale, Calif., and Northrop Grumman in El Segundo, Calif., have spent the last year studying how to meet NASA goals to develop technology that would allow future aircraft to burn 50 percent less fuel than aircraft that entered service in 1998 (the baseline for the study), with 50 percent fewer harmful emissions; and to shrink the size of geographic areas affected by objectionable airport noise by 83 percent.
"The real challenge is we want to accomplish all these things simultaneously," said ERA project manager Fay Collier. "It's never been done before. We looked at some very difficult metrics and tried to push all those metrics down at the same time."
So NASA put that challenge to industry – awarding a little less than $11 million to the three teams to assess what kinds of aircraft designs and technologies could help meet the goals. The companies have just given NASA their results.
"We'll be digesting the three studies and we'll be looking into what to do next," said Collier.
Boeing's advanced vehicle concept centers around the company's now familiar blended wing body design as seen in the sub-scale remotely piloted X-48, which has been wind tunnel tested at NASA's Langley Research Center and flown at NASA's Dryden Flight Research Center. One thing that makes this concept different from current airplanes is the placement of its Pratt & Whitney geared turbofan engines. The engines are on top of the plane's back end, flanked by two vertical tails to shield people on the ground from engine noise. The aircraft also would feature an advanced lightweight, damage tolerant, composite structure; technologies for reducing airframe noise; advanced flight controls; hybrid laminar flow control, which means surfaces designed to reduce drag; and long-span wings which improve fuel efficiency.
Lockheed Martin took an entirely different approach. Its engineers proposed a box wing design, in which a front wing mounted on the lower belly of the plane is joined at the tips to an aft wing mounted on top of the plane. The company has studied the box wing concept for three decades, but has been waiting for lightweight composite materials, landing gear technologies, hybrid laminar flow and other tools to make it a viable configuration. Lockheed's proposal combines the unique design with a Rolls Royce Liberty Works Ultra Fan Engine. This engine has a bypass ratio that is approximately five times greater than current engines, pushing the limits of turbofan technology.
For more information visit http://www.nasa.gov/topics/aeronautics/features/greener_aircraft.html
Thursday, April 5, 2012
One particular mountain on Mars, bigger than Colorado's grandest, has been beckoning would-be explorers since it was first sighted from orbit in the 1970s. Scientists have ideas about how it took shape in the middle of ancient Gale Crater and hopes for what evidence it could yield about whether conditions on Mars have favored life.
No mission to Mars dared approach it, though, until NASA's Mars Science Laboratory mission, which this August will attempt to place its one-ton rover, Curiosity, at the foot of the mountain. The moat of flatter ground between the mountain and the crater rim encircling it makes too small a touchdown target to have been considered safe without precision-landing innovations used by this mission.
To focus discussions about how Curiosity will explore the mountain during a two-year prime mission after landing, the mission's international Project Science Group has decided to call it Mount Sharp. This informal naming pays tribute to geologist Robert P. Sharp (1911-2004), a founder of planetary science, influential teacher of many current leaders in the field, and team member for NASA's first few Mars missions. Sharp taught geology at the California Institute of Technology (Caltech), in Pasadena, from 1948 until past his retirement. Life magazine named him one of the 10 best college teachers in the nation.
"Bob Sharp was one of the best field geologists this country has ever had," said Michael Malin, of Malin Space Science Systems, San Diego, principal investigator for two of Curiosity's 10 science instruments and a former student of Sharp's.
"We don't really know the origins of Mount Sharp, but we have plans for how to go there and test our theories about it, and that's just how Bob would have wanted it," Malin said.
Caltech Provost Edward Stolper, former chief scientist for the Mars Science Laboratory, said, "For much of his more than 50 years at Caltech, Bob Sharp was the central figure in its programs in the geological and planetary sciences. One of his major contributions was the building of a program in planetary sciences firmly rooted in the principles and approaches of the geological sciences.
"Moreover, through his own work on the Jet Propulsion Laboratory's early missions to Mars and the work of others that he influenced, he also had a major influence on planetary science and exploration at JPL. Recognition of this remarkable scientist and leader by the naming of Mount Sharp is highly fitting, and I hope it will serve to perpetuate his legacy."
The Mars Science Laboratory spacecraft was launched Nov. 26, 2011, bound for landing beside Mount Sharp inside Gale Crater on the evening of Aug. 5, PST (early Aug. 6, EST and Universal Time). The mission will use Curiosity to investigate whether the area has ever offered environmental conditions favorable for fostering microbial life, including chemical ingredients for life and energy for life.
Mount Sharp rises about 3 miles (5 kilometers) above the landing target on the crater floor, higher than Mount Rainier above Seattle, though broader and closer. It is not simply a rebound peak from the asteroid impact that excavated Gale Crater. A rebound peak may be at its core, but the mountain displays hundreds of flat-lying geological layers that may be read as chapters in a more complex history billions of years old.
Twice as tall as the sequence of colorful bands exposed in Arizona's Grand Canyon, the stack of layers in Mount Sharp results from changing environments in which layers are deposited, younger on top of older, eon after eon, and then partially eroded away.
Several craters on Mars contain mounds or mesas that may have formed in ways similar to Mount Sharp, and many other ancient craters remain filled or buried by rock layers. Some examples, including Gale, hold a mound higher than the surrounding crater rim, indicating that the mounds are remnant masses inside once completely filled craters. This presents a puzzle about how environmental conditions on Mars evolved.
"This family of craters that were filled or buried and then exhumed or partially exhumed raises the question of what changed," said Ken Edgett of Malin Space Sciences, principal investigator for one of Curiosity's instruments. "For a long time, sedimentary materials enter the crater and stay. Then, after they harden into rock, somehow the rock gets eroded away and transported out of the crater."
Some lower layers of Mount Sharp might tell of a lake within Gale Crater long ago, or wind-delivered sediments subsequently soaked by groundwater. Orbiters have mapped water-telltale minerals in those layers. Liquid water is a starting point in describing conditions favorable for life, but just the beginning of what Curiosity can investigate. Higher layers may be deposits of wind-blown dust after a great drying-out on Mars.
"Mount Sharp is the only place we can currently access on Mars where we can investigate this transition in one stratigraphic sequence," said Caltech's John Grotzinger, chief scientist for the Mars Science Laboratory. "The hope of this mission is to find evidence of a habitable environment; the promise is to get the story of an important environmental breakpoint in the deep history of the planet. This transition likely occurred billions of years ago -- maybe even predating the oldest well-preserved rocks on Earth."
Possible explanations for how erosion shaped the mountain after layers were deposited include swirling winds carving away the edges, and perhaps later wet episodes leaving channels down the sides and fresher sediments on the crater floor. Clues about those episodes present Curiosity with other potentially habitable environments to investigate.
For more information visit http://www.nasa.gov/mission_pages/msl/news/msl20120328.html
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