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Extreme Planet Makeover

4:53 م |

Extreme Planet Makeover

01.06.11

Extreme planet makeover interactive feature. Image credit: NASA/JPL-Caltech

The "Extreme Planet Makeover" on the NASA/JPL PlanetQuest site lets you roll up your sleeves and create your very own planet.

Balance five factors to create an Earth-like habitable world, or get wild and make your own extreme exoplanet. Use the Image Gallery feature to compare your creation with those of other Earthlings. Once you've finished creating the exoplanet of your dreams, download a picture of your custom world for posterity.

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NASA Research Team Reveals Moon Has Earth-Like Core

4:52 م |

NASA Research Team Reveals Moon Has Earth-Like Core

01.06.11

An artist's rendering of the lunar core as identified in new findings by a NASA-led research team. (NASA/MSFC/Renee Weber)

Passive Seismic Experiment deployed on the moon by Apollo 14

A close-up view of the Passive Seismic Experiment, a component of the Apollo Lunar Surface Experiments Package (ALSEP) which was deployed on the Moon by the Apollo 14 astronauts during their first extravehicular activity (EVA-1). (NASA/JSC)

Renee Weber. (NASA/MSFC)

State-of-the-art seismological techniques applied to Apollo-era data suggest our moon has a core similar to Earth's.

Uncovering details about the lunar core is critical for developing accurate models of the moon's formation. The data sheds light on the evolution of a lunar dynamo -- a natural process by which our moon may have generated and maintained its own strong magnetic field.

The team's findings suggest the moon possesses a solid, iron-rich inner core with a radius of nearly 150 miles and a fluid, primarily liquid-iron outer core with a radius of roughly 205 miles. Where it differs from Earth is a partially molten boundary layer around the core estimated to have a radius of nearly 300 miles. The research indicates the core contains a small percentage of light elements such as sulfur, echoing new seismology research on Earth that suggests the presence of light elements -- such as sulfur and oxygen -- in a layer around our own core.

The researchers used extensive data gathered during the Apollo-era moon missions. The Apollo Passive Seismic Experiment consisted of four seismometers deployed between 1969 and 1972, which recorded continuous lunar seismic activity until late-1977.

"We applied tried and true methodologies from terrestrial seismology to this legacy data set to present the first-ever direct detection of the moon's core," said Renee Weber, lead researcher and space scientist at NASA's Marshall Space Flight Center in Huntsville, Ala.

In addition to Weber, the team consisted of scientists from Marshall; Arizona State University; the University of California at Santa Cruz; and the Institut de Physique du Globe de Paris in France. Their findings are published in the online edition of the journal Science.

The team also analyzed Apollo lunar seismograms using array processing, techniques that identify and distinguish signal sources of moonquakes and other seismic activity. The researchers identified how and where seismic waves passed through or were reflected by elements of the moon's interior, signifying the composition and state of layer interfaces at varying depths.

Although sophisticated satellite imaging missions to the moon made significant contributions to the study of its history and topography, the deep interior of Earth's sole natural satellite remained a subject of speculation and conjecture since the Apollo era. Researchers previously had inferred the existence of a core, based on indirect estimates of the moon's interior properties, but many disagreed about its radius, state and composition.

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Cassini to Probe Rhea for Clues to Saturn Rings

4:51 م |

Cassini to Probe Rhea for Clues to Saturn Rings

Artist concept of the Cassini spacecraft flying by Saturn's moon Rhea on Jan 11, 2011

This artist's concept shows the third flyby of Saturn's moon Rhea by NASA's Cassini spacecraft. It is the closest flyby of Cassini's mission. Image credit: NASA/JPL-Caltech

Hemispheric color differences on Saturn's moon Rhea are apparent in this false-color view from NASA's Cassini spacecraft. Image credit: NASA/JPL/SSI
› Full image and caption

Saturn's icy moon Rhea might seem a strange place to look for clues to understanding the vast majestic rings encircling Saturn. But that's what NASA's Cassini spacecraft plans to do on its next flyby of Rhea. At closest approach, Cassini will pass within about 69 kilometers (43 miles) of the surface at 4:53 AM UTC on Tuesday, Jan. 11, which is 10:53 PM Pacific Time on Monday, Jan. 10. This flyby is the closest Cassini will get to the icy moon's surface.

Rhea, Saturn's second largest moon, is the best available chance for studying how often tiny meteoroids bombard a surface. Rhea has almost no atmosphere, which allows Cassini's cosmic dust analyzer and radio and plasma wave instrument to detect the dusty debris that flies off the surface from tiny meteoroid bombardments. Counting these dust particles ejected from Rhea's surface helps scientists estimate the bombardment rate for the Saturn system and how often the icy rings have been polluted by particles from other places in the solar system. Understanding the contamination rate will enable scientists to improve estimates of the age of the rings.

Previous attempts to count this rate in the inner part of the Saturn system have been confounded by the dusty E ring, made of icy particles spewed by the moon Enceladus. But at Rhea, scientists can sufficiently filter out the E-ring effect. The cosmic dust analyzer will also be set to look for smaller particles than it looked for during a previous Rhea flyby in March 2010.

The upcoming flyby will also enable scientists to gather more data on Rhea's very thin oxygen-and-carbon-dioxide atmosphere that was recently discovered by Cassini scientists using the ion and neutral mass spectrometer and the Cassini plasma spectrometer. Fields and particles instruments will also investigate the interaction between Rhea and the magnetic bubble around Saturn known as the magnetosphere.

Cassini will also snap pictures of the Rhea surface, a venture that will include making a global mosaic of such regions as the large Tirawa basin and the dark bluish spots around Rhea's equator. The imaging cameras will also take another look to see if there is any more evidence of a ring around Rhea.

This is the third close flyby of Saturn's moon Rhea. The closest flyby before this one was 100 kilometers (60 miles) in altitude

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Under Pressure: Stormy Weather Sensor for Hurricane Forecasting

4:48 م |

Under Pressure: Stormy Weather Sensor for Hurricane Forecasting

Click to enlarge

Hurricane Bill nears Cuba in 2009. A vertical profile from the Cloud-Aerosol Lidar and Infrared Pathfinder satellite (CALIPSO) is overlaid on an image from the Moderate-resolution Imaging Spectroradiometer (MODIS). Credit: NASA

Click to enlarge

The radar signal processor of DIABAR. Credit: NASA

Click to enlarge

The DIABAR antenna. Credit: NASA

Hurricanes need four conditions to form:

Low air pressure
Moist ocean air
Tropical winds
Warm temperatures

It’s hard to believe that, in this day and age, we don’t have a way to measure sea-level air pressure during hurricanes. NASA researchers, however, are working on a system that will improve forecasting of severe ocean weather by doing just that. The device measures sea-level air pressure, a critical component of hurricane formation – and one that has been extremely difficult to capture.

The Differential Absorption Barometric Radar (DIABAR) prototype is scheduled to make its second flight early this year.

DIABAR remotely senses barometric pressure at sea level, which is important in the prediction and forecasting of severe weather, especially hurricanes, over oceans.

But the ability to measure sea-level air pressure is a major missing link in storm observation, says Dr. Bing Lin, an atmospheric scientist at NASA Langley Research Center in Hampton, Va.

“Air pressure is a driving force of weather systems, especially under severe weather conditions like hurricanes,” he said. “For severe storms, the forecasts of the intensity and track can be significantly improved by pressure measurements.”

A Hurricane’s Life

A hurricane begins as a tropical wave, a westward-moving area of low air pressure. As warm, moist air over the ocean rises in the low air-pressure area, surrounding air replaces it, and circulation forms. This produces strong gusty winds, heavy rain and thunderclouds – a tropical disturbance.

As air pressure drops and winds sustain at 38 mph or more, the disturbance becomes a tropical depression, then a tropical storm, and finally a hurricane with sustained winds of over 73 mph.

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Hubble Snaps Image of Space Oddity

4:47 م |

Hubble Snaps Image of Space Oddity

› Print resolution image (3.9 Mb)Credit: NASA, ESA, W. Keel (University of Alabama), and the Galaxy Zoo Team
In this image by NASA's Hubble Space Telescope, an unusual, ghostly green blob of gas appears to float near a normal-looking spiral galaxy.

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Proceedings Published From 2009 Women in Astronomy Conference

4:45 م |

Proceedings Published From 2009 Women in Astronomy Conference

Lecture session at the 2009 Women in Astronomy and Space Science Conference III

A lecture session at the 2009 Women in Astronomy conference Credit: NASA, Jay FreidlanderThe Organizing Committee of the 2009 Women in Astronomy conference has published the proceedings from the year's Women in Astronomy and Space Science Conference III, titled "Women in Astronomy and Space Science 2009: Meeting the Challenges of an Increasingly Diverse Workforce." The conference was held on Oct. 21-23, 2009, at the Inn and Conference Center, University of Maryland University College, Adelphi, Md.

Nearly three hundred women and men attended the three day conference, which focused on the diversity of today's scientific professions and the challenges of tomorrow's leaders. Speakers shared their personal route to careers in areas such as instrument development, science management, non-profit organizations, and aerospace administration. Topics presented included: best practices for recruiting, promoting, mentoring, and retaining women and minorities; unconscious biases that influence how people are evaluated and demographics within the science field. There was a focus on the senior scientists who mentor and manage the workforce, the mid-career scientists who face the full range of challenges, including balancing home and work, and the early career scientists who represent the future of the field.

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NASA's Hubble Finds that Puny Stars Pack a Big Punch

4:41 م |

NASA's Hubble Finds that Puny Stars Pack a Big Punch

01.10.11

artists' concept of a red dwarf emitting powerful flares

This is an artist's concept of a red dwarf star undergoing a powerful eruption, called a stellar flare. A hypothetical planet is in the foreground. Credit: NASA/ESA/G. Bacon (STScI)

› Larger image

A deep survey of more than 200,000 stars in our Milky Way galaxy has unveiled the sometimes petulant behavior of tiny red dwarf stars. These stars, which are smaller than the Sun, can unleash powerful eruptions called flares that may release the energy of more than 100 million atomic bombs.

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