Thursday, April 19, 2012

Dark Heart of a Cosmic Collision

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.

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Tuesday, April 10, 2012

New Ideas Sharpen Focus for Greener Aircraft

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.

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