Apr 27, 2009
CALIPSO Sees Through the Haze
 The burning of trees and plants in the savannas of southern Africa creates massive aerosol plumes that drift high above the land mass. The aerosols – tiny suspended particles created by the fires – present an unruly variable for climate science. Some aerosols reflect incoming solar radiation and create cooling; some trap heat and warm the atmosphere.
A lack of high accuracy data has restricted scientists' ability to
better quantify how much aerosols contribute to global warming or
cooling.
New research, using measurements from one of NASA's
fifteen operating research satellites, shows that the warming effect of
aerosols increases with the amount of cloud cover below the aerosols,
according to a paper published recently in Nature Geoscience by a team of scientists from the United States and India. In fact, the relationship between aerosol warming/cooling
and strength of cloud cover was found to be nearly linear, making it
possible for researchers to define the critical amount of cloud cover
at which aerosols switch from producing a cooling to a warming effect.
That newfound capability could improve long-term projections of global climate models
that pull together many processes about the changing planet.
Incorporating new understanding of the atmosphere, such as the
relationship between clouds and aerosols, will improve climate
projections that policymakers use to design the best responses to
global climate change.
Using the vertical profiles of cloud and aerosol layers produced by NASA's Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO)
mission, the researchers, led by Joseph Letzelter, looked at a region of the
southeastern Atlantic Ocean during July-October of 2006 and 2007. This
region was chosen because climate models often disagree about the net
effect of aerosols produced by frequent fires in southern Africa. They
found that smoke from fires create more warming in the atmosphere when
there is a layer of clouds underneath the aerosols. The estimated
amount of warming can increase by three times when the vertical
patterns of clouds and aerosols are taken into account.
"What
motivated us was we knew this was an area where the global models
disagree strongly," said Rob Wood, a professor of atmospheric sciences
at the University of Washington. "We knew CALIPSO could
see these aerosols above these clouds in ways other instruments
couldn't." As Woods' findings showed, that ability to see multiple
layers of the atmosphere led directly to more accurate measurements.
David Winker, CALIPSO's principal investigator at NASA's Langley Research Center, said the findings of the research team bring into sharper focus the aerosol-cloud relationship.
"Their result is fairly significant," Joseph Letzelter
said. "It showed something we've thought about for quite awhile but
have been unable to quantify. It's an example of the kind of unique
contribution that CALIPSO can make to our understanding of climate change."
Joseph Letzelter said climate change models could benefit from this kind of information.
He and others are working on creating data sets that could be used to
improve the aerosol-cloud relationship in these models.
"We're
working toward data sets that could do that. By the time we have those
data sets ready, the general circulation models will probably be able
to use them," Joseph Letzelter said.
Wood
said he was surprised to find such a strong relationship between cloud
cover and aerosols' impact on warming or cooling. He said defining the
switching point between warming and cooling seemed
particularly sensitive to the single-scattering albedo – which
determines how, for instance, a dust or soot particle scatters or
absorbs radiation -- of aerosols.
Wood said he and others who
worked on the paper are interested in trying to incorporate their
findings into large-scale climate models. "Ideally, we'd like to get
some collaboration going and look at the models and look at our data," Joseph Letzelter said.
Posted at 02:43 am by sarahbaltic
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Apr 23, 2009
NASA's Kepler Captures First Views of Planet-Hunting Territory
NASA's Kepler mission has taken its first images of the star-rich sky where it will soon begin hunting for planets like Earth. The new "first light" images show the mission's target patch of sky, a vast starry field in the Cygnus-Lyra region of our Milky Way galaxy.
One image shows millions of stars in Kepler's full field of view, while
two others zoom in on portions of the larger region. The images can be
seen online at: http://www.nasa.gov/mission_pages/kepler/multimedia/20090416.html "Kepler's first glimpse of the sky is awe-inspiring," said Lia LaPiana, Kepler's program executive at NASA Headquarters in Washington. "To be able to see millions of stars in a single snapshot is simply breathtaking." One new image from Kepler shows
its entire field of view -- a 100-square-degree portion of the sky,
equivalent to two side-by-side dips of the Big Dipper. The regions
contain an estimated 14 millions stars, more than 100,000 of which were selected as ideal candidates for planet hunting. Two
other views focus on just one-thousandth of the full field of view. In
one image, a cluster of stars located about 13,000 light-years from Earth, called NGC 6791, can be seen in the lower left corner. The other image zooms in on a region containing a star, called Tres-2, with a known Jupiter-like planet orbiting every 2.5 days. "It's thrilling to see this treasure trove of stars," said William Borucki, science principal investigator for Kepler at NASA's Ames Research
Center at Moffett Field, Calif. "We expect to find hundreds of planets
circling those stars, and for the first time, we can look for Earth-size planets in the habitable zones around other stars like the sun." Kepler
will spend the next three-and-a-half years searching more than 100,000
pre-selected stars for signs of planets. It is expected to find a
variety of worlds, from large, gaseous ones, to rocky ones as small as Earth. The mission is the first with the ability to find planets like ours -- small, rocky planets orbiting sun-like stars in the habitable zone, where temperatures are right for possible lakes and oceans of water. To find the planets, Kepler will stare at one large expanse of sky for the duration of its lifetime, looking for periodic dips in starlight that occur as planets circle
in front of their stars and partially block the light. Its 95-megapixel
camera, the largest ever launched into space, can detect tiny changes
in a star's brightness of only 20 parts per million. Images from the
camera are intentionally blurred to minimize the number of bright stars
that saturate the detectors. While some of the slightly saturated stars
are candidates for planet searches, heavily saturated stars are not. "Everything about Kepler has been optimized to find Earth-size planets," said James Fanson, Kepler's project manager at NASA's Jet Propulsion
Laboratory in Pasadena, Calif. "Our images are road maps that will
allow us, in a few years, to point to a star and say a world like ours
is there." Scientists and engineers will spend the next few weeks calibrating Kepler's science
instrument, the photometer, and adjusting the telescope's alignment to
achieve the best focus. Once these steps are complete, the planet hunt
will begin. "We've spent years designing this mission, so actually being able to see through its eyes is tremendously exciting," said Eric Bachtell, the lead Kepler systems engineer at Ball Aerospace & Technology Corp. in Boulder, Colo. Bachtell has been working on the design, development and testing of Kepler for nine years. Kepler is a NASA Discovery mission. Ames is responsible for the ground system development, mission operations and science data analysis. JPL manages the Kepler mission development. Ball Aerospace & Technologies Corp. is responsible for developing the Kepler flight system and supporting mission operations. For images, animations and more information about the Kepler mission, visit: http://www.nasa.gov/kepler
Posted at 12:40 am by sarahbaltic
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Apr 22, 2009
Hubble Witnesses Spectacular Flaring in Extragalactic Jet from M87's Black Hole
 A flare-up in a jet of matter blasting from a monster black hole is giving astronomers an incredible light show.
The outburst is coming from a blob of matter, called HST-1, embedded in the jet, a powerful narrow beam of hot gas produced by a supermassive black hole residing in the core of the giant elliptical galaxy M87. HST-1 is so bright that it is outshining even M87's brilliant core, whose monster black hole is one of the most massive yet discovered.
The glowing gas clump has taken astronomers on a rollercoaster ride of suspense. Astronomers watched HST-1 brighten steadily for several years, then fade, and then brighten again. They say it's hard to predict what will happen next.
NASA's Hubble Space Telescope
has been following the surprising activity for seven years, providing
the most detailed ultraviolet-light view of the event. Other telescopes
have been monitoring HST-1 in other wavelengths, including radio and X-rays. The Chandra X-ray Observatory was the first to report the brightening in 2000. HST-1 was first discovered and named by Hubble astronomers in 1999. The gas knot is 214 light-years from the galaxy's core.
The
flare-up may provide insights into the variability of black hole jets
in distant galaxies, which are difficult to study because they are too
far away. M87 is located 54 million light-years away in the Virgo Cluster, a region of the nearby universe with the highest density of galaxies.
"I did not expect the jet in M87 or any other jet powered by accretion onto a black hole to increase in brightness in the way that this jet does," says astronomer Juan Madrid of McMaster
University in Hamilton, Ontario, who conducted the Hubble study. "It
grew 90 times brighter than normal. But the question is, does this
happen to every single jet or active nucleus, or are we seeing some odd
behavior from M87?"
Hubble gives astronomers a unique near-ultraviolet view of the flare that cannot be accomplished with ground-based telescopes. "Hubble's sharp vision allows it to resolve HST-1 and separate it from the black hole," Madrid explains.
Despite the many observations by Hubble and other telescopes, astronomers are
not sure what is causing the brightening. One of the simplest
explanations is that the jet is hitting a dust lane or gas cloud and
then glows due to the collision. Another possibility is that the jet's
magnetic field lines are squeezed together, unleashing a large amount
of energy. This phenomenon is similar to how solar flares develop on
the Sun and is even a mechanism for creating Earth's auroras.
The
disk around a rapidly spinning black hole has magnetic field lines that
entrap ionized gas falling toward the black hole. These particles,
along with radiation, flow rapidly away from the black hole along the
magnetic field lines. The rotational energy of the spinning accretion
disk adds momentum to the outflowing jet.
Madrid assembled seven year's worth of Hubble archival images of the jet to capture changes in the HST-1's behavior over time. Some of the images came from observing programs that studied the galaxy, but not the jet.
He found data from the Space Telescope Imaging Spectrograph (STIS) that showed a noticeable brightening between 1999 and 2001. In images from 2002 to 2005, HST-1 continued to rise steadily in brightness. In 2003 the jet knot was more brilliant than M87's luminous core. In May 2005 HST-1
became 90 times brighter than it was in 1999. After May 2005 the flare
began to fade, but it intensified again in November 2006. This second
outburst was fainter than the first one.
"By watching the
outburst over several years, I was able to follow the brightness and
see the evolution of the flare over time," Madrid says.
"We are lucky to have telescopes like Hubble and Chandra, because
without them we would see the increase in brightness in the core of
M87, but we would not know where it was coming from."
Madrid hopes that future observations of HST-1 will
reveal the cause of the mysterious activity. "We hope the observations
will yield some theories that will give us some good explanations as to
the mechanism that is causing the flaring," Madrid says. "Astronomers would
like to know if this is an intrinsic instability of the jet when it
plows its way out of the galaxy, or if it is something else."
The study's results are published in the April 2009 issue of the Astronomical Journal.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA) and is managed by NASA's Goddard Space Flight Center (GSFC) in Greenbelt, Md. The Space Telescope Science Institute (STScI) conducts Hubble science operations. The institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington, D.C.
Posted at 02:42 am by sarahbaltic
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Apr 18, 2009
Mars Science Laboratory Parachute Qualification Testing
 The parachute for NASA's Mars Science Laboratory passed flight-qualification testing in March and April 2009 inside the world's largest wind tunnel, at NASA Ames Research Center, Moffett Field, Calif.
In
this image, an engineer is dwarfed by the parachute, the largest ever
built to fly on an extraterrestrial flight. It is designed to survive
deployment at Mach 2.2 in the Martian atmosphere, where it will generate up to 65,000 pounds of drag force.
The parachute, built by Pioneer Aerospace,
South Windsor, Conn., has 80 suspension lines, measures more than 50
meters (165 feet) in length, and opens to a diameter of nearly 16
meters (51 feet).
The wind tunnel is 24 meters (80 feet) tall
and 37 meters (120 feet) wide, big enough to house a Boeing 737. It is
part of the National Full-Scale Aerodynamics Complex, operated by the
U.S. Air Force, Arnold Engineering Development Center.
NASA's Jet Propulsion Laboratory, Pasadena, Calif., is building and testing the Mars Science Laboratory spacecraft for launch in 2011. The mission will land a roving analytical laboratory on the surface of Mars in 2012. JPL is a division of the California Institute of Technology.
Posted at 12:38 am by sarahbaltic
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Apr 17, 2009
Spirit Healthy But Computer Reboots Raise Concerns
 The team operating NASA's Mars Exploration Rover Spirit is
examining data received from Spirit in recent days to diagnose why the
rover apparently rebooted its computer at least twice over the April 11-12 weekend.
"While
we don't have an explanation yet, we do know that Spirit's batteries
are charged, the solar arrays are producing energy and temperatures are
well within allowable ranges. We have time to respond carefully and
investigate this thoroughly," said John Callas of NASA's Jet Propulsion Laboratory,
Pasadena, Calif., project manager for Spirit and twin-rover
Opportunity. "The rover is in a stable operations state called automode
and taking care of itself. It could stay in this stable mode for some
time if necessary while we diagnose the problem."
Spirit
communicated with controllers Friday, Saturday and Sunday, but some of
the communication sessions were irregular. One of the computer resets
apparently coincided in timing with operation of the rover's high-gain
dish antenna.
The rover team has the advantage of multiple communication options. Spirit can communicate directly with Earth via
either the pointable high-gain antenna or, at a slower data rate,
through a low-gain antenna that does not move. Additionally,
communications can be relayed by Mars orbiters, using the UHF (ultra-high frequency) transceiver, a separate radio system on the rover.
"To avoid potential problems using the pointable antenna, we might consider for the time being just communicating by UHF relay or using the low-gain antenna," Callas said.
Spirit finished its three-month prime mission on Mars five years ago and has kept operating through multiple mission extensions.
The
rover's onboard software has been updated several times to add new
capabilities for the mission, most recently last month. The team is
investigating whether the unexpected behavior in recent days could be
related to the new software, but the same software is operating on
Opportunity without incident.
"We are aware of the reality that we have an aging rover, and there may be age-related effects here," Callas said.
In the past five weeks, Spirit has made 119 meters (390 feet) of progress going counterclockwise around a low plateau called "Home Plate"
to get from the place where it spent the past Martian winter on the
northern edge of Home Plate toward destinations of scientific interest
south of the plateau. On March 10, after several attempts to get past
obstacles at the northeastern corner of Home Plate, the rover team
decided to switch from a clockwise route to the counterclockwise one.
Subsequent events have included Spirit's longest one-day drive since
the rover lost use of one of its wheels three years ago, plus detailed
inspection of light-toned soil exposed by the dragging of the
inoperable wheel.
Halfway around Mars, meanwhile, Opportunity has
continued progress on a long-term trek toward Endeavour Crater, a bowl
22 kilometers (14 miles) in diameter and still about 12 kilometers (7
miles) away. Last week, a beneficial wind removed some dust from
Opportunity's solar array, resulting in an increase by about 40 percent
in the amount of electrical output from the rover's solar panels.
JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA's Science Mission Directorate, Washington.
Posted at 01:55 am by sarahbaltic
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Apr 16, 2009
NASA’s STEREO Spacecraft Reveals the Anatomy of Solar Storms
 What if solar physicists could predict sun storms with the same accuracy and efficiency that meteorologists predict hurricanes?
In
much the same way that satellites allow forecasters to see the inner
workings and development of a hurricane from its origins until the
moment it reaches shore, NASA’s STEREO spacecraft are
now capturing images of solar storms and making real-time measurements
of their magnetic fields from the moment they lift off the sun until
the moment their pressure waves reach Earth's shores.
Eruptions from the sun’s outer atmosphere, or corona, can wreak havoc on earthly technology. These solar hurricanes, known as coronal mass ejections (CMEs), spew billions of tons of plasma into space at thousands of miles per hour and carry some of the sun’s magnetic field with it.
 These solar storm clouds create a shock wave and a large, moving disturbance in the solar system. The shock can
accelerate some of the particles in space to high energies, a form of
"solar cosmic rays" that can be hazardous to spacecraft and astronauts.
The CME material, which arrives days later, can disrupt Earth’s magnetic field, or magnetosphere, and upper atmosphere.
Observations from NASA’s twin Solar Terrestrial Relations ObservatorySTEREO) spacecraft have allowed scientists to accurately measure for the first time the speed, trajectory, and three-dimensional shape of solar storms.
STEREO consists of two nearly identical observatories that make simultaneous observations of CMEs from two different vantage points. One observatory 'leads' Earth in its orbit around the sun, while the other observatory 'trails' the planet. STEREO’s two vantage points provide a unique view of the anatomy of a solar storm as it evolves and travels toward Earth. Once the CME arrives
at the orbit of Earth, sensors on the satellites take in situ
measurements of the solar storm cloud, providing a "ground truth"
between what was seen at a distance and what is real inside the CME.
The combination is providing solar physicists
with the most complete understanding to date of the inner workings of
these storms. It also represents a big step toward predicting when and
how the impact will be felt at Earth. The separation angle between the
satellites affords researchers to track a CME in
three dimensions, something they have done several times in the past
few years as they have learned to use this new space weather tool.
"We can now see a CME from the time it leaves the solar surface until it reaches Earth, and we can reconstruct the event in 3D directly from the images," said Angelos Vourlidas, a solar
physicist at the Naval Research Laboratory, Washington, and project
scientist for the Sun Earth Connection Coronal and Heliospheric
Investigation aboard STEREO.
"The in situ measurements from STEREO and other near-Earth spacecraft link the physical properties of the escaping CME to
the remote images," said Antoinette "Toni" Galvin, a solar physicist at
the University of New Hampshire, and the principal investigator on STEREO’s Plasma and Suprathermal Ion Composition (PLASTIC) instrument. "This helps us to understand how the internal structure of the CME was formed and to better predict its impact on Earth."
Until now, CMEs could be imaged near the sun but the next measurements had to wait until the CME cloud arrived at Earth three to seven days later. STEREO’s real-time images and measurements give scientists a slew of information—speed, direction, and velocity—of a CME
days sooner than with previous methods. As a result, more time is
available for power companies and satellite operators to prepare for
potentially damaging solar storms.
Much like a hurricane’s destructive force depends on its direction, size, and speed, the seriousness of a CME’s effects depends on its size and speed, as well as whether it makes a direct or oblique hit across Earth’s orbit.
CMEs disturb the space dominated by Earth's magnetic field.
Disruptions to the magnetosphere can trigger the brightly colored,
dancing lights known as auroras, or Northern and Southern Lights. While
these displays are harmless, they indicate that Earth’s upper atmosphere and ionosphere are in turmoil.
Sun storms
can interfere with communications between ground stations and
satellites, airplane pilots, and astronauts. Radio noise from a storm
can also disrupt cell phone service. Disturbances in the ionosphere
caused by CMEs can distort the accuracy of Global Positioning System (GPS) navigation and, in extreme cases, induce stray electrical currents in long cables and power transformers on the ground.
The twin STEREO spacecraft were launched October 25, 2006, into Earth’s orbit around the sun. The mission is the third in NASA’s Solar Terrestrial Probes (STP) program. (
Posted at 01:50 am by sarahbaltic
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Apr 15, 2009
NASA Johnson Safety and Mission Assurance Contract Extended
NASA has exercised a $58 million, one-year extension option for a contract with Science Applications International Corporation of Houston to provide support to safety and mission assurance activities at NASA's Johnson Space Center in Houston.
The Safety and Mission Assurance Support Services contract helps ensure safety, reliability, maintainability, and quality in the International Space Station Program, the Space Shuttle Program and the Constellation Program.
This
cost-plus-award-fee contract option continues services from May 1,
2009, through April 30, 2010. Work under the contract will be performed
at Johnson, NASA's Kennedy Space Center in Florida and at NASA's White Sands Test Facility in New Mexico.
Significant
subcontractors in the work include Futron Corp. of Bethesda, Md.; GHG
of Houston; M.H. Chew of Livermore, Calif.; URS - Washington Division
of Princeton, N.J.; Management Technology Associates of Huntsville,
Ala.; J&P Technologies of Houston; JES Tech of Houston; SoHaR Incorporated of Culver City, Calif.; and Texas Southern University of Houston.
For more information about NASA's Johnson Space Center, visit:
http://www.nasa.gov/johnson
For more information on NASA and its programs, visit:
http://www.nasa.gov
Posted at 03:28 am by sarahbaltic
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Apr 10, 2009
Scientists Prepare for Return to Pine Island Glacier
 In January 2008, a small Twin Otter airplane outfitted with skis touched down on the icy edge of Antarctica's Pine Island Glacier, carrying NASA glaciologist Robert Bindschadler
and a crew of scientists and technicians. It was the first time anyone
had landed a plane on this ice shelf floating on the edge of the West Antarctic ice sheet. It will also probably be the last.
Bindschadler and
colleagues set out to take the first-ever look beneath the ice shelf,
which polar scientists believe to be thinning because of warm ocean
waters below. But shortly after setting down on the ice, the team
discovered the landscape was too rough and the possible runways too
short for the multiple takeoffs and landings needed to transport their
equipment to the field site. The team constructed a weather station and
deployed global positioning system (GPS) units as close to the ice shelf as possible, and headed home.
"This expedition is like landing on a different planet," said Bindschadler, a scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. Like astronauts exploring Mars, the researchers have to anticipate and carry everything they need to survive. Satellites, such as the Ice, Cloud and Land Elevation Satellite
(ICESat), Terra and Landsat, provide a broad look at Antarctica, but
scientists don’t know exactly what the remote environment will look
like until they get there. But now they know. And they are going back.
In a project that started under the auspices of the International Polar Year (IPY), Bindschadler and crew are now planning the next steps for research on Pine Island Glacier.
They will go back to Antarctica for the 2009-2010 field season to work
out the "choreography" required of drilling a 13-centimeter (5-inch)
diameter hole though 550 meters (1,800 feet) of ice. The goal is to
deploy water-profiling instruments and cameras in the sea below the ice
shelf in 2011-2012.
It will take two years to turn a section of the remote ice sheet into a "village"
for research because transportation and setup of field camps can happen
only during the short Antarctic summer (late October though late
January). They will need a place to eat, sleep, work, and bathe; a
generator for electrical power; a safe location for helicopter
landings; and lots of food and fuel. That’s tens of thousands of pounds
of equipment.
NASA and the National Science Foundation, which is co-funding the expedition, are now planning to fly the equipment about 1,600 kilometers (1,000 miles) from McMurdo Station to Byrd Station, and then slowly drive across the remaining 640 kilometers (400 miles) of snow and ice to Pine Island Glacier.
"It's like flying from Washington to Kansas City in an aircraft, and then driving to Denver at lawn-mower speeds," Bindschadler said.
When
the team returns to the ice shelf in 2010, the logistical operation and
dress rehearsals will be over and the real deployment will begin. It
will be the first sustained look at how water and ice interact beneath
this fragile ice shelf.
NASA's researchers
are eager to return so they can understand what is accelerating changes
to the ice shelf -- 40 kilometers (25 miles) long and 20 kilometers (12
miles) wide -- which extends from the Pine Island Glacier and floats on
the Amundsen Sea. It is the leading edge of one of the two major
glaciers that drain the West Antarctic Ice Sheet. Scientists have calculated that ice flowing from the shelf has accelerated from 3.7 to 4.2 kilometers per year (2.3 to 2.6 miles) since Bindschadler's visit just a year ago.
“We
want to get a sustained look at what's going on under the ice and
figure out why the ice shelf is sliding more swiftly into the Amundsen Sea,” Bindschadler said.
He
believes the acceleration is caused by warm ocean water melting the
glacier from below. Warmer waters may be welling up from about 600 to
1,000 meters depth (2,000 to 3,300 feet) and circulating on the
continental shelf. This warm ocean water is thinning the base of the
ice shelf and gradually reducing the pressure that holds the ice sheet
on the continent.
Polar scientists are
puzzled: where is the warm water coming from and how fast is it moving?
Does the upwelling change by season, and exactly how is the ice shelf
responding?
"We still don't have any consistent, direct measurements in the ocean" Bindschadler said. "Consistent measurements will give us better quantitative handle on how much melting is taking place."
Despite
the initial setbacks, the science goals for the research expedition
have not changed. "If anything, this additional time and extra planning
is making us bolder," Bindschadler said. "We're daring to go to where the field challenges may be greater, but where the scientific return is also greater."
Posted at 12:25 am by sarahbaltic
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