Category Archives: Science

Gulf shark study surprises

Researchers at Dauphin Island Sea Lab in Alabama, conducting a two year study focusing on the diets of Tiger Sharks in the Gulf of Mexico, have made a surprising discovery: not only are the sharks feeding on fish and other marine organisms, they are also feeding on land-based birds, such as woodpeckers, tanagers, meadowlarks, catbirds, kingbirds, and swallows.

“We were not expecting to see this. It certainly prompts a series of questions, the most obvious being, how does a land bird end up in the water as food for sharks? Certainly, bird migrations across the Gulf are incredibly strenuous treks that result in large numbers of bird deaths over water from exhaustion, but there may be other factors at play here. We’re going to be taking a look at this over the next year and see if there are other causative circumstances that are contributing to these bird deaths,” said lead researcher Dr. Marcus Drymon.

The study findings may lend support to an issue American Bird Conservancy (ABC – the nation’s leading bird conservation organization) has been raising for several years, and which was referenced in a 2005 federal government study Interactions Between Migrating Birds and Offshore Oil and Gas Platforms in the Northern Gulf of Mexico. That study made reference to a bird migration phenomenon in which potentially large numbers of night-migrating birds become fatally attracted to lighted oil and gas platforms.

These avian fatal attractions occur more often on cloudy nights, and can involve hundreds or even thousands of birds that apparently confuse the platform lights with stars by which they navigate. The birds become trapped in a cone of light – either reluctant or unable to leave it and fly into a wall of darkness.

“Some birds circle in confusion before crashing into the platform or falling from the sky, exhausted. Others land on the platform where there is no food or drinking water. Some of these birds continue on quickly, but many stay for hours or even days. When finally able to leave, they can be in a weakened state and unable to make landfall, and ultimately, are more vulnerable to predation,” said Dr. Christine Sheppard, Bird Collisions Campaign Manager for ABC.

Studies have shown that hundreds of thousands of birds die from oil and gas platform lighting effects in the Gulf every year. A study often cited is a 2007 report by F.J.T. Van De Laar, Green Light to Birds – An Investigation into the Effect of Bird-Friendly Lighting, which looked at oil and gas platform lighting impacts to birds in the North Sea. The paper suggested that the key to solving the problem lies in the use alternative lights using specific wavelengths. Using green lighting at platforms – as opposed to red or white lights – would nearly eliminate the circling behavior, the study suggested.

Another study, titled Green Light for Nocturnally Migrating Birds and published in Ecology and Society Journal in 2008, showed similar findings – “…..strongest bird responses were found in white light, which seems to interfere with visual orientation ………. the artificial light becomes a strong false orientation cue and birds can get trapped by the beam. ………The bird responses observed in the colored-light conditions are similar to those of previous studies in the laboratory where red light caused disorientation……… it was found that green light caused no or minor disturbance of orientation.”

However, a solution is far from clear as other studies have produced findings that suggest the issue may be more complex. Some studies have also indicated bird attraction could be mitigated greatly by cycling lighting off and on but observed that optimum cycling rhythms have yet to be determined. Studies of cell towers show that strobing white and red lights are far less dangerous than steady burning ones. A simple application of this strategy has been used for the 9/11 memorial in lights, turned on each year on the anniversary of the attacks on the Twin Towers of the World Trade Center. They are monitored and briefly turned off when too many birds accumulate in the beams.

“Some countries, such as the Netherlands, have already instituted bird friendly lighting on oil and gas platforms off their coast. The 2005 study for the Department of the Interior called for research on the issue, but no further action was taken until ABC, in an attempt to advance a solution, requested it. A federal study is now planned for 2013,” Sheppard said.

There are approximately 6,000 oil and gas platforms in the Gulf of Mexico.

NASA’s twin Grail craft reunite

The second of NASA’s two Gravity Recovery And Interior Laboratory (GRAIL) spacecraft has successfully completed its planned main engine burn and is now in lunar orbit. Working together, GRAIL-A and GRAIL-B will study the moon as never before.

"The twin GRAIL spacecraft will vastly expand our knowledge of our moon and the evolution of our own planet. We begin this year reminding people around the world that NASA does big, bold things in order to reach for new heights and reveal the unknown," said NASA Administrator Charles Bolden. 

GRAIL-B achieved lunar orbit at 2:43 p.m. PST (5:43 p.m. EST) today. GRAIL-A successfully completed its burn yesterday at 2 p.m. PST (5 p.m. EST). The insertion maneuvers placed the spacecraft into a near-polar, elliptical orbit with an orbital period of approximately 11.5 hours. Over the coming weeks, the GRAIL team will execute a series of burns with each spacecraft to reduce their orbital period to just under two hours. At the start of the science phase in March 2012, the two GRAILs will be in a near-polar, near-circular orbit with an altitude of about 34 miles (55 kilometers).

During GRAIL’s science mission, the two spacecraft will transmit radio signals precisely defining the distance between them. As they fly over areas of greater and lesser gravity caused by visible features such as mountains and craters, and masses hidden beneath the lunar surface, the distance between the two spacecraft will change slightly.

Scientists will translate this information into a high-resolution map of the moon’s gravitational field. The data will allow scientists to understand what goes on below the lunar surface. This information will increase knowledge of how Earth and its rocky neighbors in the inner solar system developed into the diverse worlds we see today.

Each spacecraft carries a small camera called GRAIL MoonKAM (Moon Knowledge Acquired by Middle school students) with the sole purpose of education and public outreach. The MoonKAM program is led by Sally Ride, America’s first woman in space, and her team at Sally Ride Science in collaboration with undergraduate students at the University of California in San Diego.  
 
GRAIL MoonKAM will engage middle schools across the country in the GRAIL mission and lunar exploration. Thousands of fifth- to eighth-grade students will select target areas on the lunar surface and send requests to the GRAIL MoonKAM Mission Operations Center in San Diego. Photos of the target areas will be sent back by the GRAIL satellites for students to study. 
 
A student contest that began in October 2011 also will choose new names for the spacecraft. The new names are scheduled to be announced in January 2012. Ride and Maria Zuber, the mission’s principal investigator at the Massachusetts Institute of Technology in Cambridge, chaired the final round of judging.

NASA’s Jet Propulsion Laboratory in Pasadena, Calif., manages the GRAIL mission for NASA’s Science Mission Directorate, Washington. The GRAIL mission is part of the Discovery Program managed at NASA’s Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems in Denver built the spacecraft. JPL is a division of the Çalifornia Institute of Technology in Pasadena.

For more information about GRAIL, visit:  http://www.nasa.gov/grail

Information about MoonKAM is available online at:  http://solarsystem.nasa.gov/grail/education.cfm

Mars rover finds minerals deposited by water

NASA’s Mars Exploration Rover Opportunity has found bright veins of a mineral, apparently gypsum, deposited by water. Analysis of the vein will help improve understanding of the history of wet environments on Mars.

"This tells a slam-dunk story that water flowed through underground fractures in the rock," said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for Opportunity. "This stuff is a fairly pure chemical deposit that formed in place right where we see it. That can’t be said for other gypsum seen on Mars or for other water-related minerals Opportunity has found. It’s not uncommon on Earth, but on Mars, it’s the kind of thing that makes geologists jump out of their chairs."

The latest findings by Opportunity were presented Wednesday at the American Geophysical Union’s conference in San Francisco.

The vein examined most closely by Opportunity is about the width of a human thumb (0.4 to 0.8 inch, or 1 to 2 centimeters), 16 to 20 inches (40 to 50 centimeters) long, and protrudes slightly higher than the bedrock on either side of it. Observations by the durable rover reveal this vein and others like it within an apron surrounding a segment of the rim of Endeavour Crater. None like it were seen in the 20 miles (33 kilometers) of crater-pocked plains that Opportunity explored for 90 months before it reached Endeavour, nor in the higher ground of the rim.

Last month, researchers used the Microscopic Imager and Alpha Particle X-ray Spectrometer on the rover’s arm and multiple filters of the Panoramic Camera on the rover’s mast to examine the vein, which is informally named "Homestake."  The spectrometer identified plentiful calcium and sulfur, in a ratio pointing to relatively pure calcium sulfate.

Calcium sulfate can exist in many forms, varying by how much water is bound into the minerals’ crystalline structure. The multi-filter data from the camera suggest gypsum, a hydrated calcium sulfate. On Earth, gypsum is used for making drywall and plaster of Paris. Observations from orbit had detected gypsum on Mars previously. A dune field of windblown gypsum on far northern Mars resembles the glistening gypsum dunes in White Sands National Monument in New Mexico.

"It is a mystery where the gypsum sand on northern Mars comes from," said Opportunity science-team member Benton Clark of the Space Science Institute in Boulder, Colo. "At Homestake, we see the mineral right where it formed. It will be important to see if there are deposits like this in other areas of Mars."  

The Homestake deposit, whether gypsum or another form of calcium sulfate, likely formed from water dissolving calcium out of volcanic rocks. The calcium combined with sulfur that was either leached from the rocks or introduced as volcanic gas, and it was deposited as calcium sulfate into an underground fracture that later became exposed at the surface.

Throughout Opportunity’s long traverse across Mars’ Meridiani plain, the rover has driven over bedrock composed of magnesium, iron and calcium sulfate minerals that also indicate a wet environment billions of years ago. The highly concentrated calcium sulfate at Homestake could have been produced in conditions more neutral than the harshly acidic conditions indicated by the other sulfate deposits observed by Opportunity.

"It could have formed in a different type of water environment, one more hospitable for a larger variety of living organisms," Clark said.

Homestake and similar-looking veins appear in a zone where the sulfate-rich sedimentary bedrock of the plains meets older, volcanic bedrock exposed at the rim of Endeavour. That location may offer a clue about their origin.

Opportunity and its rover twin, Spirit, completed their three-month prime missions on Mars in April 2004. Both rovers continued for years of extended missions and made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life. Spirit stopped communicating in 2010. Opportunity continues exploring, currently heading to a sun-facing slope on the northern end of the Endeavour rim fragment called "Cape York" to keep its solar panels at a favorable angle during the mission’s fifth Martian winter.

"We want to understand why these veins are in the apron but not out on the plains," said the mission’s deputy principal investigator, Ray Arvidson, of Washington University in St. Louis. "The answer may be that rising groundwater coming from the ancient crust moved through material adjacent to Cape York and deposited gypsum, because this material would be relatively insoluble compared with either magnesium or iron sulfates."

NASA launched the next-generation Mars rover, the car-sized Curiosity, on Nov. 26. It is slated for arrival at the planet’s Gale Crater in August 2012. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover Project for the NASA Science Mission Directorate in Washington. For more information about the rovers, visit http://www.nasa.gov/rovers and http://marsrovers.jpl.nasa.gov . You can follow the project on Twitter at http://twitter.com/MarsRovers and on Facebook at http://www.facebook.com/marsrovers .

Oceans of water found in space

Using data from the Herschel Space Observatory, astronomers have detected for the first time cold water vapor enveloping a dusty disk around a young star. The findings suggest that this disk, which is poised to develop into a solar system, contains great quantities of water, suggesting that water-covered planets like Earth may be common in the universe. Herschel is a European Space Agency mission with important NASA contributions.

Scientists previously found warm water vapor in planet-forming disks close to a central star. Evidence for vast quantities of water extending out into the cooler, far reaches of disks where comets take shape had not been seen until now.

The more water available in disks for icy comets to form, the greater the chances that large amounts eventually will reach new planets through impacts.

"Our observations of this cold vapor indicate enough water exists in the disk to fill thousands of Earth oceans," said astronomer Michiel Hogerheijde of Leiden Observatory in The Netherlands. Hogerheijde is the lead author of a paper describing these findings in the Oct. 21 issue of the journal Science.

The star with this waterlogged disk, called TW Hydrae, is 10 million years old and located about 175 light-years away from Earth, in the constellation Hydra. The frigid, watery haze detected by Hogerheijde and his team is thought to originate from ice-coated grains of dust near the disk’s surface. Ultraviolet light from the star causes some water molecules to break free of this ice, creating a thin layer of gas with a light signature detected by Herschel’s Heterodyne Instrument for the Far-Infrared, or HIFI.

"These are the most sensitive HIFI observations to date," said Paul Goldsmith, NASA project scientist for the Herschel Space Observatory at the agency’s Jet Propulsion Laboratory in Pasadena, Calif. "It is a testament to the instrument builders that such weak signals can be detected."

TW Hydrae is an orange dwarf star, somewhat smaller and cooler than our yellow-white sun. The giant disk of material that encircles the star has a size nearly 200 times the distance between Earth and the sun. Over the next few million years, astronomers believe matter within the disk will collide and grow into planets, asteroids and other cosmic bodies. Dust and ice particles will assemble as comets.

As the new solar system evolves, icy comets are likely to deposit much of the water they contain on freshly created worlds through impacts, giving rise to oceans. Astronomers believe TW Hydrae and its icy disk may be representative of many other young star systems, providing new insights on how planets with abundant water could form throughout the universe.

Herschel is a European Space Agency cornerstone mission launched in 2009, carrying science instruments provided by consortia of European institutes. NASA’s Herschel Project Office based at JPL contributed mission-enabling technology for two of Herschel’s three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the U.S. astronomical community. Caltech manages JPL for NASA.

For ESA’s Herschel website, click here

Spacecraft begins new mapping orbit

NASA’s Dawn spacecraft has completed a gentle spiral into its new science orbit for an even closer view of the giant asteroid Vesta. Dawn began sending science data on Sept. 29 from this new orbit, known as the high altitude mapping orbit (HAMO).

In this orbit, the average distance from the spacecraft to the Vesta surface is 420 miles (680 kilometers), which is four times closer than the previous survey orbit. The spacecraft will operate in the same basic manner as it did in the survey orbit. When Dawn is over Vesta’s dayside, it will point its science instruments to the giant asteroid and acquire data, and when the spacecraft flies over the nightside, it will beam that data back to Earth.

Perhaps the most notable difference in the new orbit is the frequency with which Dawn circles Vesta. In survey orbit, it took Dawn three days to make its way around the asteroid. Now in HAMO, the spacecraft completes the same task in a little over 12 hours.  HAMO is scheduled to last about 30 Earth days, during which Dawn will circle Vesta more than 60 times. For about 10 of those 30 days, Dawn will peer straight down at the exotic landscape below it during the dayside passages. For about 20 days, the spacecraft will view the surface at multiple angles.

Scientists will combine the pictures to create topographic maps, revealing the heights of mountains, the depths of craters and the slopes of plains. This will help scientists understand the geological processes that shaped Vesta.

HAMO, the most complex and intensive science campaign at Vesta, has three primary goals: to map Vesta’s illuminated surface in color, provide stereo data, and acquire visible and infrared mapping spectrometer data. In addition, it will allow improved measurements of Vesta’s gravity.

Dawn launched in September 2007 and arrived at Vesta in July 2011. Since beginning its first survey orbit in August, Dawn has been extensively imaging this intriguing world, sending back a bounty of images and other data. NASA-funded scientists and European scientists on the Dawn mission team will present a wealth of new findings at the joint
meeting of the American Astronomical Society’s Division for Planetary Sciences and the European Planetary Science Congress next week at La Cite Internationale des Congres Nantes Metropole, Nantes, France.  

These findings about the giant asteroid Vesta will include information about the new coordinate system and official names of Vesta’s prominent features.

A Dawn mission news conference will be held Monday, Oct. 3, 2011 at 12:15 p.m. CEST (3:15 a.m. PDT/6:15 a.m. EDT). The Division for Planetary Sciences will provide live Web streaming of this news conference, click here for more.

"The team has been in awe of what they have seen on the surface of Vesta," said Christopher Russell, Dawn principal investigator, at UCLA. "We are sharing those discoveries with the greater scientific community and with the public."  

Following a year at Vesta, the spacecraft will depart in July 2012 for Ceres, where it will arrive in 2015. Dawn’s mission to Vesta and Ceres is managed by the Jet Propulsion Laboratory, Pasadena, Calif., for NASA’s Science Mission Directorate in Washington.  JPL is a division of the California Institute of Technology in Pasadena. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science. Orbital Sciences Corp. in Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are international partners on the mission team.

The image and more information about the Dawn mission are online at: http://www.nasa.gov/dawn .  To follow the mission on Twitter, visit: http://www.twitter.com/NASA_Dawn