May 9, 2007, 11:29 PM CT

Evidence Of Early Martian Volcanic Activity

A plateau on Mars known as Home Plate shows evidence of long-past explosive volcanic activity, say researchers on NASA's Mars Exploration Rover mission. And data collected during the rover Spirit's initial pass across the 90-meter (295 feet) wide plateau also supports earlier findings indicating that water once existed at or beneath the planet's surface.

"One of the neatest pictures we've taken with the rovers": A false-color image of a "bomb sag" preserved in layered rocks on the lower slopes of Home Plate. Bomb sags form in volcanic explosions on Earth when rocks ejected skyward by the explosion fall into soft deposits, deforming them as they land.

The research appeared in the May 4 issue of the journal Science.

Home Plate's finely layered appearance made it one of the most tantalizing targets within Spirit's reach in Gusev Crater, said Steve Squyres, the mission's principal investigator and the Goldwin Smith Professor of Astronomy at Cornell. The rover captured its first panoramic image of Home Plate in August 2005 from the summit of Husband Hill and reached the plateau in the Columbia Hills' inner basin in February 2006.

It quickly sent back an image Squyres called "one of the neatest pictures we've taken with the rovers." The image shows a small (4 centimeter) rock fragment nestled within a downward deflection in otherwise ruler-straight lines of layering -- a feature likely to be what geologists call a bomb sag. These usually form when a rock fragment (the bomb) is thrown upward in an explosion; then lands in deformable material, causing the material to sag beneath it......... Posted by: Sean      Read more         Source

May 7, 2007, 11:14 PM CT

Largest, brightest supernova ever seen

An exploding star first observed last September is the largest and most luminous supernova ever seen, as per University of California, Berkeley, astronomers, and may be the first example of a type of massive exploding star rare today but probably common in the very early universe.

Unlike typical supernovas that reach a peak brightness in days to a few weeks and then dim into obscurity a few months later, SN2006gy took 70 days to reach full brightness and stayed brighter than any previously observed supernova for more than three months. Nearly eight months later, it still is as bright as a typical supernova at its peak, outshining its host galaxy 240 million light years away.

UC Berkeley post-doctoral fellows Nathan Smith and David Pooley estimate the star's mass at between 100 and 200 times that of the sun. Such massive stars are so rare that galaxies like our own Milky Way may contain only a dozen out of a stellar population of 400 billion.

"This was a truly monstrous explosion, a hundred times more energetic than a typical supernova," said Smith, who led a team of astronomers from UC Berkeley and the University of Texas. "That means the star that exploded might have been as massive as a star can get, about 150 times that of our sun. We've never seen that before"......... Posted by: Sean      Read more         Source

May 6, 2007, 5:34 PM CT

GIOVE-A transmits first navigation message

Earlier this week, GIOVE-A successfully transmitted its first navigation message, containing the information needed by user receivers to calculate their position. Previous to reaching this milestone, the satellite had been broadcasting only the data needed for measuring the receiver-to-satellite distance.

The first Galileo navigation message was created by the navigation signal generator unit on board GIOVE-A, using content prepared by the GIOVE Mission Segment. This week-one navigation message was upassociated with GIOVE-A on 2 May from the Guildford ground station operated by Surrey Satellite Technology Ltd (United Kingdom) and then transmitted from the spacecraft to the users. The objective of the test was to demonstrate an end-to-end link between the Mission Segment and the user receivers. The navigation message is being generated for demonstration purposes only no service guarantee is provided.

The complete radio transmission from GIOVE-A carries a navigation signal and a navigation message. The navigation signal contains the information needed to accurately measure the distance from the satellite to the user receiver. The navigation message provides the timing and spacecraft orbit data needed to calculate the time and exact position of the satellite. One of the main tasks of the GIOVE Mission Segment is the generation of this navigation message......... Posted by: Sean      Read more         Source

April 29, 2007, 7:19 PM CT

Cosmic Lighthouses

The end of a star's life, when the star has become heavy enough, is marked by a huge explosion - a supernova. For a few weeks, a supernova looks almost as bright as a whole galaxy containing billions of stars. Physicists designate the brightest of these supernovae as Type Ia. Their brightness, measured from the Earth, is a measure of their distance from us - but there are several uncertainties. "The question still remains: how suitable are supernovae really for measuring distance? For example, the knowledge that the Universe is expanding rapidly is largely based on observations of supernovae," explains Prof. Wolfgang Hillebrandt. All type Ia supernovae exhibit similar levels of brightness, but they are not exactly consistent.

Researchers from the Max Planck Institute for Astrophysics and the National Astronomical Institute of Italy have now made a breakthrough. They have come to the conclusion that the explosion energy of the type Ia supernovae is almost consistent - it is equivalent to the fusion energy which a white dwarf with around one and half times the mass of the Sun can develop. However, the amount of radioactive nickel and medium-weight chemical elements such as silicon vary from supernova to supernova and explain the difference in their brightness. The more nickel a supernova contains, the brighter it shines......... Posted by: Sean      Read more         Source

April 24, 2007, 10:39 PM CT

Back to the Moon

Of the two luminaries that dominate our sky, it is the moon that is of particular interest to the Lunar Reconnaissance Orbiter (LRO) project. The LRO will travel to the moon in late fall 2008, mapping the surface to help pave the way for humans to return. It will help prepare us for extended surface exploration on the moon and for subsequent missions to Mars and other distant destinations. Lunar surface exploration will help us to practice living, working, and gathering science data before we venture into riskier territory.

The Lunar Reconnaissance Orbiter will take the first strides in researching a complex habitat -- a hostile environment without atmosphere or clouds, with daytime temperatures reaching as high as 250 degrees Fahrenheit (123 degrees Celsius) and as low as minus 450 degrees Fahrenheit (233 degrees Celsius), and sunlight lasting two weeks. The spacecraft will identify the volatile terrain so we can land safely. It should also be able to identify water on the surface, if it sees it.

The spacecraft being built at NASA's Goddard Space Flight Center in Greenbelt, Md., will include six instruments and a technology demonstration. The objective is to collect the highest resolution and most comprehensive data set ever returned from the moon, or gathered by any planetary mission, to help achieve NASA's goal of returning human explorers safely to the moon. The data gathered by instruments on the Lunar Reconnaissance Orbiter will provide more information than all six Apollo surface missions managed to produce. While the Apollo missions focused on gaining science from the band around the moon's equator, the Lunar Reconnaissance Orbiter will circle the poles. It will spend at least one year in low, polar orbit, with all the instruments working simultaneously to collect detailed information about the lunar environment. Data sets will be deposited in the publicly accessible Planetary Data System within six months of its primary mission completion......... Posted by: Sean      Read more         Source

April 24, 2007, 10:32 PM CT

Satellites offer sunny outlook

Far beyond signaling the days weather, clouds play a key role in regulating and understanding climate. A team of scientists recently completed a project to confirm what NASA satellites are telling us about how changes in clouds can affect climate in the coldest regions on Earth.

Clouds and their traits their temperature, depth, size and shape of their droplets play a significant role in how much of the sun's radiation reaches Earth's surface and what amount of heat energy Earth reflects back into the atmosphere. In 2006, NASA simultaneously launched a pair of satellites, CloudSat and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), which together use state-of-the-art instruments as they orbit the globe to reveal detailed information about clouds and their effect on climate.

Researchers predict that certain changes in cloud properties can accelerate climate change. "The polar regions are very sensitive indicators of climate change," said Deborah Vane, project manager and deputy principal investigator for the CloudSat mission at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It's been well reported now that the polar ice caps are undergoing net melting. There's a complicated interaction between clouds and climate in polar regions that can contribute to temperature changes, and, in turn, speed the rate at which ice melts"......... Posted by: Sean      Read more         Source

April 11, 2007, 9:30 PM CT

Water In Extrasolar Planet Atmosphere

For the first time, water has been identified in the atmosphere of an extrasolar planet. Through a combination of previously published Hubble Space Telescope measurements and new theoretical models, Lowell Observatory astronomer Travis Barman has found good evidence for water absorption in the atmosphere of transiting planet HD209458b. This result was recently accepted for publication in the Astrophysical Journal.

"We now know that water vapor exists in the atmosphere of one extrasolar planet and there is good reason to think that other extrasolar planets contain water vapor," said Barman.

Water vapor (or steam) has been expected to be present in the atmospheres of nearly all of the known extrasolar planets, even those that orbit closer to their parent star than Mercury is to our Sun. For the majority of extrasolar planets, their close proximity to their parent star has made detecting water and other compounds difficult.

The identification reported here takes advantage of the fact that HD209458b, as seen from Earth, passes directly in front of its star every three and half days. As a planet passes in front of a star, its atmosphere blocks a different amount of the starlight at different wavelengths. In particular, absorption by water in the atmosphere of a giant planet makes the planet appear larger across a specific part of the infrared spectrum in comparison to wavelengths in the visible spectrum......... Posted by: Sean      Read more         Source

April 11, 2007, 9:22 PM CT

Close-ups Of Extrasolar Planets

In July, 2005, the Deep Impact spacecraft released a probe that blasted a crater in comet Tempel 1, spilling its elements into space so researchers could discover its composition. The assault was justified because comets are believed to be leftovers from the formation of our solar system, so learning more about them helps to understand how our solar system came to be.

Since those fireworks, the spacecraft has cruised silently through space, healthy and able to take on another mission, if needed. The Deep Impact team realized that with the spacecraft already built and launched, extra discoveries could be made at very little cost, a bonus for an already successful mission.

The team put together a proposal to use the spacecraft's telescope to observe the atmospheres of alien worlds, and to visit another comet. The proposed extended mission is called EPOXI (Extrasolar Planet Observation and Deep Impact Extended Investigation), and it has received $500,000 from NASA for an initial study to determine the requirements and costs in greater detail.

If approved, as Deep Impact passes by Earth on December 31, 2007, it will use our planet's gravity to direct itself to comet Boethin. While it cruises toward the comet, the first part of the extended mission -- the investigation of alien worlds --would begin in January, 2008. More than 200 alien (extrasolar) planets have been discovered to date. Most of these are detected indirectly, by the gravitational pull they exert on their parent star. Directly observing extrasolar planets is very difficult, because the star is so brilliant in comparison to the planet. Planets simply get lost in the glare, like fireflies near a headlight......... Posted by: Sean      Read more         Source

April 10, 2007, 8:45 PM CT

Mystery spiral (galaxy) arms explained?

Using a quartet of space observatories, University of Maryland astronomers may have cracked a 45-year mystery surrounding two ghostly spiral arms in the galaxy M106.

The Maryland team, led by Yuxuan Yang, took advantage of the unique capabilities of NASAs Chandra X-ray Observatory, NASAs Spitzer Space Telescope, the European Space Agencys XMM-Newton X-ray observatory, and data obtained almost a decade ago with NASAs Hubble Space Telescope.

M106 (also known as NGC 4258) is a stately spiral galaxy 23.5 million light-years away in the constellation Canes Venatici. In visible-light images, two prominent arms emanate from the bright nucleus and spiral outward. These arms are dominated by young, bright stars, which light up the gas within the arms. "But in radio and X-ray images, two additional spiral arms dominate the picture, appearing as ghostly apparitions between the main arms," says team member Andrew Wilson of the University of Maryland. These so-called "anomalous arms" consist mostly of gas.

"The nature of these anomalous arms is a long-standing puzzle in astronomy," says Yang. "They have been a mystery since they were first discovered in the early part of 1960s".

By analyzing data from XMM-Newton, Spitzer, and Chandra, Yang, Bo Li, Wilson, and Christopher Reynolds, all at the University of Maryland at College Park, have confirmed earlier suspicions that the ghostly arms represent regions of gas that are being violently heated by shock waves......... Posted by: Sean      Read more         Source

April 10, 2007, 7:51 PM CT

NASA cloud mission April 25

A satellite carrying two University of Colorado at Boulder instruments to study silvery-blue clouds that mysteriously form 50 miles above Earth's polar regions every year is slated to launch from Vandenberg Air Force Base in California on April 25.

The spectacular clouds, known as noctilucent clouds, will be probed by NASA's Aeronomy of Ice in the Mesosphere mission, or AIM, to determine why they form and how they change. First spotted in Earth's atmosphere in 1885, the clouds have been increasing in frequency in recent decades and may be correlation to increases in carbon dioxide and methane emissions tied to human activity on Earth, said Senior Research Scientist Dave Rusch of CU-Boulder's Laboratory for Atmospheric and Space Physics.

The NASA mission, which consists of two CU-Boulder instruments and an instrument from Utah State University, is being managed by CU-Boulder's LASP and will be controlled from the Space Technology Building at the CU Research Park. The mission's principal investigator is Jim Russell of Hampton University in Virginia.

"We have seen a definite increase in the brightness of these clouds in the past 25 years, which gives us cause for concern," said Rusch, principal investigator for one of the three AIM instruments. "This mission will give us an unprecedented look at how the mesosphere, which is a very sensitive region of Earth's atmosphere, is changing"......... Posted by: Sean      Read more         Source