Tuesday, March 30, 2010

Extreme Weather Impacts Migratory Birds

birdsEvery year, hurricanes and droughts wreak havoc on human lives and property around the world. And according to a pair of new NASA-funded studies, migratory birds also experience severe impacts to their habitats and populations from these events.

While this may not seem like a revelation, the researchers were surprised to find that migratory bird species located as far as 60 miles (100 kilometers) from a hurricane’s path had experienced a long-term loss in population. Those populations took up to five years to rebound from the damage to their forest environments.

At the same time, researchers found that some migratory bird species could experience population losses as high as 13 percent when rainfall levels fall dramatically and cause drought in plains regions. The studies appear in the March edition of Global Change Biology.

"These studies suggest that whether a hurricane or a drought batters an area, migratory habits -- whether birds migrate south or stay put after breeding season -- are a strong predictor of how birds will fare," said Anna Pidgeon, an avian ecologist at the University of Wisconsin-Madison and a NASA-funded co-author of both studies.

"We believe changes in weather and climate are fundamental drivers of migration but, until now, we’ve known little of how changes in climate compel changes in migratory patterns," said Woody Turner, manager of the biodiversity program at NASA’s Headquarters in Washington. "The correlations don’t necessarily mean the environment alone is forcing migratory changes, but they offer a good place to start looking."

Thursday, March 25, 2010

Northeastern U.S. Flooding "GOES" to the Movies Via Satellite

The northeastern U.S. was subjected to heavy flooding and damage from late winter storms, and the Geostationary Operational Environmental Satellite, GOES-12 captured a movie of those storms as they dumped heavy rainfall between March 8 and 16, 2010.

"Following the Nor'easter 'parade of blizzards' in February this year, another week-long parade of storms flooded the upper Midwest and Northeastern U.S. in March," said Dennis Chesters of the NASA GOES Project at NASA's Goddard Space Flight Center in Greenbelt, Md. "The merge of three storms in the Midwest was unusual, where the normal pattern is a series of spring storms carried by the prevailing westerlies (winds)."

The GOES-12 operated by the National Oceanic and Atmospheric Administration (NOAA) captures images of U.S. East Coast weather. Those images from March 8-16, 2010 were compiled into a movie by the NASA GOES Project at NASA's Goddard Space Flight Center, Greenbelt, Md.

The movie was created by overlaying the clouds observed several times per hour by NOAA's GOES Imager onto a true-color map previously derived from NASA's Moderate Imaging Spectroradiometer (MODIS) land-mapping instrument. The infrared channels on GOES detect clouds day and night, which are portrayed as grey for low clouds and white for high clouds. The movie compresses nine days into two minutes. It illustrates how continental-scale land/sea/air phenomena come together to make large late winter storms.

Heavy rains that hit the northeast cause flooding, fatalities, power outages and damages. Downed trees from rain-soaked roots toppled power lines. Outages were reported in Connecticut, Maine, New Jersey, New York and Pennsylvania. Literally thousands of trees were reported felled in Connecticut and New York. Flooding forced evacuations and put roadways under water. As far north as Maine, parts of the state received more than eight inches of rain.

As of March 19 for the month of March, Boston recorded 7.45" of rain; Bridgeport, Conn. reported 4.02"; Newark, N.J. reported 5.24"; New York City reported 4.72"; and Portland, Maine reported 3.57" of rain. Most of that rainfall can be attributed to these events.

Wednesday, March 24, 2010

HELP X-15 Pilot Robert White Dies

On July 17, 1962, Major Robert White flew the X-15 to an altitude of 314,750 feet, or 59 miles, becoming the first "winged astronaut." He was the first to fly at Mach 4, Mach 5 and Mach 6; he was the first to fly a winged vehicle into space. After a career of 'firsts' White died on March 17, 2010.

White was one of the initial pilots selected for the X-15 program, representing the Air Force in the joint program with NASA, the Navy, and North American Aviation. Between April 13, 1960, and Dec. 14, 1962, he made 16 flights in the rocket-powered aircraft.

His July 17, 1962, flight to an altitude of 314,750 feet set a world record. This was 59.6 miles, significantly higher than the 50 miles the Air Force accepted as the beginning of space, qualifying White for astronaut wings. The X-15 rocket-powered aircraft were built by North American Aviation and developed to provide in-flight information and data on aerodynamics, structures, flight controls and the physiological aspects of high-speed, high-altitude flight.

A follow-on program used the aircraft as testbeds to carry various scientific experiments beyond the Earth's atmosphere on a repeated basis. Information gained from the highly successful X-15 program contributed to the development of the Mercury, Gemini and Apollo manned spaceflight programs, and also the space shuttle program. The X-15s made a total of 199 flights and the first aircraft X-15-1, serial number 56-6670, is now located at the National Air and Space Museum in Washington, D.C.

According to an article by Al Hallonquist, White's achievements as an X-15 pilot "allowed him to become the fifth American to attain astronaut wings and only the second Air Force pilot to do this."

Tuesday, March 23, 2010

Cassini Shows Saturnian Roller Derby, Strange Weather

From our vantage point on Earth, Saturn may look like a peaceful orb with rings worthy of a carefully raked Zen garden, but NASA's Cassini spacecraft has been shadowing the gas giant long enough to see that the rings are a rough and tumble roller derby. It has also revealed that the planet itself roils with strange weather and shifting patterns of charged particles. Two review papers to be published in the March 19 issue of the journal Science synthesize Cassini's findings since arriving at Saturn in 2004.

"This rambunctious system gives us a new feel for how an early solar system might have behaved," said Linda Spilker, a planetary scientist and the new Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "This kind of deep, rich data can only be collected by an orbiting spacecraft, and we look forward to the next seven years around Saturn bringing even more surprises."

This natural color view from the Cassini spacecraft highlights the myriad gradations in the transparency of Saturn's inner rings.
In the paper describing the elegant mess of activity in the rings, lead author Jeff Cuzzi, Cassini's interdisciplinary scientist for rings and dust who is based at NASA Ames Research Center, Moffett Field, Calif., describes how Cassini has shown us that collisions are routine and chunks of ice leave trails of debris in their wakes. Spacecraft data have also revealed how small moons play tug-of-war with ring material and how bits of rubble that would otherwise join together to become moons are ultimately ripped apart by the gravitational pull that Saturn exerts.

During equinox, the period when sunlight hits the rings exactly edge-on, Cassini witnessed rings that are normally flat - about tens of meters (yards) thick - being flipped up as high as the Rocky Mountains.

The spacecraft has also shown that the rings are composed mostly of water ice, with a mysterious reddish contaminant that could be rust or small organic molecules similar to those found in red vegetables on Earth.

"It has been amazing to see the rings come to life before our very eyes, changing even as we watch, being colorful and taking on a tangible, 3-D nature," Cuzzi said. "The rings were still a nearly unstructured object in even the best telescopes when I was a grad student, but Cassini has brought us an intimate familiarity with them."

Cuzzi said Cassini scientists were surprised to find such fine-scale structure nearly everywhere in the rings, forcing them to be very careful about generalizing their findings across the entire ring disk. The discovery that the rings are clumpy has also called into question some of the previous estimates for the mass of the rings because there might be clusters of material hidden inside of the clumps that have not yet been measured.

Wednesday, March 17, 2010

See Spot on Jupiter. See Spot Glow.

New thermal images from powerful ground-based telescopes show swirls of warmer air and cooler regions never seen before within Jupiter's Great Red Spot, enabling scientists to make the first detailed interior weather map of the giant storm system.

The observations reveal that the reddest color of the Great Red Spot corresponds to a warm core within the otherwise cold storm system, and images show dark lanes at the edge of the storm where gases are descending into the deeper regions of the planet. These types of data, detailed in a paper appearing in the journal Icarus, give scientists a sense of the circulation patterns within the solar system's best-known storm system.

"This is our first detailed look inside the biggest storm of the solar system," said Glenn Orton, a senior research scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., who was one of the authors of the paper. "We once thought the Great Red Spot was a plain old oval without much structure, but these new results show that it is, in fact, extremely complicated."

Sky gazers have been observing the Great Red Spot in one form or another for hundreds of years, with continuous observations of its current shape dating back to the 19th century. The spot, which is a cold region averaging about 110 Kelvin (minus 260 degrees Fahrenheit) is so wide about three Earths could fit inside its boundaries.

The thermal images obtained by giant 8-meter (26-foot) telescopes used for this study -- the European Southern Observatory's Very Large Telescope in Chile, the Gemini Observatory telescope in Chile and the National Astronomical Observatory of Japan's Subaru telescope in Hawaii -- have provided an unprecedented level of resolution and extended the coverage provided by NASA's Galileo spacecraft in the late 1990s. Together with observations of the deep cloud structure by the 3-meter (10-foot) NASA Infrared Telescope Facility in Hawaii, the level of thermal detail observed from these giant observatories is comparable to visible-light images from NASA's Hubble Space Telescope for the first time.

One of the most intriguing findings shows the most intense orange-red central part of the spot is about 3 to 4 Kelvin (5 to 7 degrees Fahrenheit) warmer than the environment around it, said Leigh Fletcher, the lead author of the paper, who completed much of the research as a postdoctoral fellow at JPL and is currently a fellow at the University of Oxford in England. This temperature differential might not seem like a lot, but it is enough to allow the storm circulation, usually counter-clockwise, to shift to a weak clockwise circulation in the very middle of the storm. Not only that, but on other parts of Jupiter, the temperature change is enough to alter wind velocities and affect cloud patterns in the belts and zones.

"This is the first time we can say that there's an intimate link between environmental conditions -- temperature, winds, pressure and composition - and the actual color of the Great Red Spot," Fletcher said. "Although we can speculate, we still don't know for sure which chemicals or processes are causing that deep red color, but we do know now that it is related to changes in the environmental conditions right in the heart of the storm."

Tuesday, March 16, 2010

Solar 'Conveyor Belt' Runs at Record-High Speeds

This images shows the association of magnetic field with sunspots and coronal loops. It begins with images in "white light" (visible light) from the ESA/NASA SOHO Mission MDI instrument showing the presence of sunspots (darker, cooler regions about the size of the Earth) and the 27-day rotation of the sun. The movie then dissolves to magnetic images from MDI showing how strong magnetic fields are associated with sunspots but weaker magnetic elements are always present and in constant motion. (White represents field directed out of the Sun while black represents field directed into the sun.) The movie then dissolves to images obtained in extreme ultraviolet light by the EIT instrument on SOHO. This reveals the hot coronal loops that are associated with the magnetic features. The movie ends with a zoom-in to a single region which is followed as it rotates across the visible disk of the sun by the extreme ultraviolet imaging instrument on the NASA TRACE spacecraft. This final segment illustrates how the constant motion of the magnetic elements produces impulsive heating of material in the coronal magnetic loops.

Friday, March 12, 2010

Cassini Data Show Ice and Rock Mixture Inside Titan

By precisely tracking NASA's Cassini spacecraft on its low swoops over Saturn's moon Titan, scientists have determined the distribution of materials in the moon's interior. The subtle gravitational tugs they measured suggest the interior has been too cold and sluggish to split completely into separate layers of ice and rock.

The finding, to be published in the March 12 issue of the journal Science, shows how Titan evolved in a different fashion from inner planets such as Earth, or icy moons such as Jupiter's Ganymede, whose interiors have split into distinctive layers.

"These results are fundamental to understanding the history of moons of the outer solar system," said Cassini Project Scientist Bob Pappalardo, commenting on his colleagues' research. Pappalardo is with NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We can now better understand Titan's place among the range of icy satellites in our solar system."

Scientists have known that Titan, Saturn's largest moon, is about half ice and half rock, but they needed the gravity data to figure out how the materials were distributed. It turns out Titan's interior is a sorbet of ice studded with rocks that probably never heated up beyond a relatively lukewarm temperature. Only in the outermost 500 kilometers (300 miles) is Titan's ice devoid of any rock, while ice and rock are mixed to various extents at greater depth.

artist's illustration shows the likely interior structure of Saturn's moon Titan

"To avoid separating the ice and the rock, you must avoid heating the ice too much," said David J. Stevenson, one of the paper's co-authors and a professor of planetary science at the California Institute of Technology in Pasadena. "This means that Titan was built rather slowly for a moon, in perhaps around a million years or so, back soon after the formation of the solar system."

This incomplete separation of ice and rock makes Titan less like Jupiter's moon Ganymede, where ice and rock have fully separated, and perhaps more like another Jovian moon, Callisto, which is believed to have a mixed ice and rock interior. Though the moons are all about the same size, they clearly have diverse histories.

The Cassini measurements help construct a gravity map, which may help explain why Titan has a stunted topography, since interior ice must be warm enough to flow slowly in response to the weight of heavy geologic structures, such as mountains.

Creating the gravity map required tracking minute changes in Cassini's speed along a line of sight from Earth to the spacecraft as it flew four close flybys of Titan between February 2006 and July 2008. The spacecraft took paths between about 1,300 to 1,900 kilometers (800 to 1,200 miles) above Titan.

"The ripples of Titan's gravity gently push and pull Cassini along its orbit as it passes by the moon and all these changes were accurately recorded by the ground antennas of the Deep Space Network within 5 thousandths of a millimeter per second [0.2 thousandths of an inch per second] even as the spacecraft was over a billion kilometers [more than 600 million miles] away," said Luciano Iess, a Cassini radio science team member at Sapienza University of Rome in Italy, and the paper's lead author. "It was a tricky experiment."

Wednesday, March 10, 2010

Mars Dunes: On the Move?

Movement of ripples on dark sand dunes in the Nili Patera region of MarsNew studies of ripples and dunes shaped by the winds on Mars testify to variability on that planet, identifying at least one place where ripples are actively migrating and another where the ripples have been stationary for 100,000 years or more.

Patterns of dunes and the smaller ripples present some of the more visually striking landforms photographed by cameras orbiting Mars. Investigations of whether they are moving go back more than a decade.

Two reports presented at the 41st Lunar and Planetary Sciences Conference near Houston this week make it clear that the answer depends on where you look. Both reports used images from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter, which allows examination of features as small as about a meter, or yard, across.

One report is by Simone Silvestro of the International Research School of Planetary Sciences at Italy's G. d'Annunzio University, and his collaborators. They investigated migration of ripples and other features on dark dunes within the Nili Patera area of Mars' northern hemisphere. They compared an image taken on Oct. 13, 2007, with another of the same dunes taken on June 30, 2007. Most of the dunes in the study area are hundreds of meters long. Ripples form patterns on the surfaces of the dunes, with crests of roughly parallel ripples spaced a few meters apart.

Careful comparison of the images revealed places where ripples on the surface of the dunes had migrated about 2 meters (7 feet) -- the largest movement ever measured in a ripple or dune on Mars. The researchers also saw changes in the shape of dune edges and in streaks on the downwind faces of dunes.

Monday, March 08, 2010

Antarctic Collision Forms Rhode Island-Sized Berg

Iceberg - itself nearly the size of Rhode Island -- collided with an Antarctic glacier last month, forming a new berg still larger than the European nation of Luxembourg.

At 58 miles by 24 miles in size, the B-09B iceberg (1,392 square miles) is comparable to the state of Rhode Island (1,545 square miles), which is wider but not quite so long. After lingering near the Mertz Glacier in Eastern Antarctica for several years, the massive B-09B collided with the glacier tongue on February 12 or 13, breaking it away from the rest of the glacier. The former glacier tongue formed a new iceberg nearly as large as B-09B.

The iceberg formed from the Mertz Glacier Tongue is 48 miles long and 24 miles wide (1,152 square miles) and has a mass of 700 to 800 billion tons, reported BBC News. The images below, all from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on NASA’s Aqua satellite, show the iceberg and glacier tongue before and after the collision.

Antarctic Iceberg Collision
The top image is from Feb. 7, 2010, when B-09B was approaching the Mertz Glacier Tongue. Chunks of sea ice float in the water between the smooth iceberg and the coast. It is clear that the iceberg and the glacier tongue are trapping the ice in place. The water beyond the tongue and the iceberg is black in these images, and contains far less ice. The ice tongue itself is an extension of the Mertz Glacier, created as the ice flows down the mountain and onto the water. Glacier tongues grow longer year by year until they eventually break off, calving a new iceberg. The Mertz Glacier Tongue was beginning to break before the B-09B iceberg rammed it. Dark horizontal cracks were visible in the ice tongue on February 7.

Antarctic Iceberg Collision
Sometime on February 12 or 13, B-09B struck the ice tongue. Clouds hid the event in MODIS satellite images, but on the afternoon of February 13, the clouds had thinned just enough to reveal that the ice tongue had broken away in the collision. The next cloud-free view of the region on February 20 shows the two icebergs. The glacier tongue had clearly broken along the rifts that were visible in early February.

Antarctic Iceberg Collision

Over the course of the next week, the former Mertz Glacier Tongue pivoted away from the glacier like a door hinged at the point where B-09B hit it (lower image).

The glacier tongue had previously contributed to keeping a section of the ocean free of ice, a condition known as a polynya. The polynya provided a significant feeding site for wildlife like penguins. The shorter tongue may not protect the area from sea ice, reducing or even eliminating the polynya and the access to food it provided.

The B9 iceberg broke from the Ross Ice Shelf in West Antarctica some time in 1987. It took the massive iceberg more than two decades to drift slowly out of the Ross Sea and along the coast to the Mertz Glacier in East Antarctica. Along the way, it broke apart, one segment becoming the massive B-09B iceberg that collided with the glacier tongue in February 2010.

Sunday, March 07, 2010

Is That Saturn's Moon Titan or Utah?

Sikun Labyrinthus on Saturn's moon Titan
Planetary scientists have been puzzling for years over the honeycomb patterns and flat valleys with squiggly edges evident in radar images of Saturn's moon Titan. Now, working with a "volunteer researcher" who has put his own spin on data from NASA's Cassini spacecraft, they have found some recognizable analogies to a type of spectacular terrain on Earth known as karst topography. A poster session today, Thursday, March 4, at the Lunar and Planetary Science Conference in The Woodlands, Texas, displays their work.

Karst terrain on Earth occurs when water dissolves layers of bedrock, leaving dramatic rock outcroppings and sinkholes. Comparing images of White Canyon in Utah, the Darai Hills of Papua New Guinea, and Guangxi Province in China to an area of connected valleys and ridges on Titan known as Sikun Labyrinthus yields eerie similarities. The materials may be different - liquid methane and ethane on Titan instead of water, and probably some slurry of organic molecules on Titan instead of rock - but the processes are likely quite similar.

"Even though Titan is an alien world with much lower temperatures, we keep learning how many similarities there are to Earth," said Karl Mitchell, a Cassini radar team associate at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "The karst-like landscape suggests there is a lot happening right now under the surface that we can't see."

Indeed, Mitchell said, if the karst landscape on Titan is consistent with Earth's, there could very well be caves under the Titan surface.

Work on these analogies was spearheaded by Mike Malaska of Chapel Hill, N.C., an organic chemist by trade and a contributor in his spare time to unmannedspaceflight.com, a Web site for amateur space enthusiasts to try their hand at visualizing NASA data. Malaska approached radar team member Jani Radebaugh at Brigham Young University in Provo, Utah, about collaborative work after meeting her at last year's Lunar and Planetary Science Conference.

"I've been in love with Titan since Cassini beamed down the first images of Titan's Shangri-La sand sea," Malaska said. "It's been amazing for the public to see data come down so quickly and get data sets so rich that you can practically imagine riding along with the spacecraft."

Radebaugh steered Malaska toward a swath of landscape imaged by the radar instrument on Dec. 20, 2007. Malaska traced out patterns in the landscape on his computer and classified them into different types of valley patterns. He saw that some of the valleys had no apparent outlets and wondered where the fluid and material went.